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VMC data now on the Planetary Science Archive!

This update was written by Eleni Ravanis, an ESA Young Graduate Trainee working on the Mars Express Visual Monitoring Camera.

It’s official – data from the Visual Monitoring Camera (VMC) instrument onboard our Mars Express mission is now in the Planetary Science Archives (PSA)! The data comes from observations taken of the Red Planet between 2007 to mid-2020, as well as observations of the release of the Beagle 2 lander in 2003, calibrated for scientific use.

The PSA

The Planetary Science Archive (PSA) is the central repository for all scientific data returned by ESA’s Solar System missions. Originally, the VMC was an engineering instrument (you can read more about the history of VMC here).

Previously, VMC data was only available via a Flickr page, but the dataset released today is the first ‘science data’ release for the instrument, and is the culmination of several years of hard work by the VMC team!

*A view of VMC data taken in 2018 in the PSA interface*

What’s new?

How is the data on the PSA different to that already on Flickr? The newly released data is processed using a new ‘processing pipeline’ developed by the VMC team, which includes colleagues from the UPV-EHU Planetary Sciences Group in Bilbao. This data is now calibrated (more in the next paragraph) and is also available in different formats: raw data is available as RAW and PNGs, and calibrated data is available in FITS and PNG format.

*A view of VMC data taken in 2020 in the PSA interface*

The dataset release also has labels associated with each individual VMC image that contain further metadata, such as the Martian year and solar longitude (Ls), and an indication of the image resolution. Finally, there are a number of documents which explain the instrument and processing procedure in further detail.

Calibration

No on-ground calibration exists for the VMC instrument as is the case for other science instruments, so the VMC team had to be creative in their efforts!

There are two standard image calibration techniques applied to VMC images: ‘dark-current correction’ (which accounts for noise produced by the sensor) and ‘flat-fielding’ (which accounts for variations in pixel sensitivity). Normally, images for dark current correction are taken in controlled conditions so that as little light hits the detector as possible, for example by keeping the lens cap on. A flat-field image is made by taking a picture of a uniformly-lit screen, for example amateur photographers might take a picture of a piece of white paper at a short distance from their camera. Since the VMC is already at Mars, this wasn’t possible for us! Instead, the Monitoring Camera took observations of a dark part of sky to create the dark-current image, and then took images of flat portions of Mars that were well and uniformly illuminated to create the file for flat-field correction.

If you want to know more about this calibration, check out the VMC ‘Experiment to Archive Interface Control Document’ (EAICD) which has been released with this new VMC dataset.

*Collage of VMC images. From left to right, top to bottom:*
Image 1: Dust/water ice over the north pole, 4th October 2019, Image 2: The Arsia Mons Elongated Cloud (AMEC), 12th November 2008, Image 3: View of the Olympus Mons caldera,19th October 2019, Image 4: A double cyclone at the edge of the north pole, 16th June 2012, Image 5: Full disk of Mars with the south pole visible, 17th November 2016, Image 6: A close-up view of part of Valles Marineris with hazes present, 12th November 2018, Image 7: The Tharsis Volcanoes and Olympus Mons, 9th June 2010, Image 8: Cloud over Olympus Mons, 9th January 2019, Image 9: Textured patterns in the north polar cap, 1st January 2020, Image 10: Polar hoods (water ice clouds) over the north polar cap, 28th December 2010, Image 11: Valles Marineris canyon system, 1st July 2008, Image 12: Full disk of Mars with the Tharsis volcanos visible, 22nd October 2017, Image 13: Local dust storm over the north polar cap, 6th September 2016, Image 14: Syrtis Major, 9th March 2020, Image 15: Twilight clouds on Mars, 25th November 2019, Image 16: Close up of the south pole of Mars, 8th August 2010.

What can we do with the data? Science!

Why is this dataset release of interest? We’re hoping that scientists will be able to use this data to study Mars, and if you’d like to get a flavour of the work done so far, take a look at these presentations on Martian Twilight clouds and this VMC science dataset release from the recent EPSC conference. As for the general public, the backlog of images is much easier to navigate in the PSA than on Flickr. Therefore, we’re hoping this will help you peruse images of Mars to your heart’s content!

VMC images will continue to be available in Flickr, and these calibrated datasets will become available on the PSA at the same timescale as for other instruments (no earlier than 6 months after they are taken). We hope you’re as excited about seeing them as we are!

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This update was written by Eleni Ravanis, an ESA Young Graduate Trainee working on the Mars Express Visual Monitoring Camera.

The PSA

What’s new?

Calibration

No on-ground calibration exists for the VMC instrument as is the case for other science instruments, so the VMC team had to be creative in their efforts!

If you want to know more about this calibration, check out the VMC ‘Experiment to Archive Interface Control Document’ (EAICD) which has been released with this new VMC dataset.

What can we do with the data? Science!

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Keeping our eyes on Earth open

In response to the coronavirus outbreak, people across the globe are being asked to work from home where possible in order to limit personal contact and reduce the further spread of the infection.

As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

Four of ESA’s interplanetary missions have recently been put into safe standby – their instruments turned off in order to minimise the number of people required at mission control. But what implications does the pandemic have for flying Earth observation missions?

Keeping Earth observation spacecraft in orbit

It is normal for spacecraft to drift slightly off course, into orbits that aren’t ideal for science observations and operations. One of the most important jobs for mission teams is to keep their spacecraft on the right track.

*ESA’s Aeolus – The first-ever satellite to directly observe wind profiles from space*

For Earth-observing satellites flying in low-Earth orbit, this means constantly countering the effects of atmospheric drag. Over time, friction from faint wisps of atmosphere even several hundred kilometres up causes orbits to ‘decay’, meaning spacecraft slowly edge back down to Earth.

They therefore require an upwards nudge from their thrusters – called a manoeuvre – every now and then to prevent them being dragged too far down into the atmosphere.

*Cryosat data showing the gradual advance of the Filchner-Ronne ice shelf in Antarctica*

It takes months to years for this downward movement to put them in any trouble – where they could actually burn up in the atmosphere – but the motion is enough to move spacecraft out of the correct orbit to take science observations.

The aim right now is to maintain science gathering through ‘orbital maintenance’, with minimal people on site. Some missions, such as Aeolus and Sentinel-1, require as much as one manoeuvre every week to keep them in science orbits.

If needed, these manoeuvres could stop. Science gathering would therefore temporarily end, but it would mean even more people could stay at home. A larger manoeuvre would then be needed at a later date to bring them back into position, but the spacecraft themselves would be fine.

Earth observation satellites are also at risk of in-space collisions. On average, ESA moves each of its Earth orbiting spacecraft out of the way of oncoming debris or another satellite, twice per year.

Find out more about how teams are continuing the vital work needed to protect spacecraft from the busy highways of space, here.

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In response to the coronavirus outbreak, people across the globe are being asked to work from home where possible in order to limit personal contact and reduce the further spread of the infection.

As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

Keeping Earth observation spacecraft in orbit

They therefore require an upwards nudge from their thrusters – called a manoeuvre – every now and then to prevent them being dragged too far down into the atmosphere.

Find out more about how teams are continuing the vital work needed to protect spacecraft from the busy highways of space, here.

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Protecting Mars Express during coronavirus outbreak

In response to the Covid-19 outbreak, people across the globe are being asked to work from home where possible in order to limit personal contact and reduce the further spread of the infection.

As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

But what implications does this have for the 17-year-old Mars Express spacecraft, currnently in orbit around the Red Planet?

*Launched in June 2003, Mars Express became ESA’s first-ever visit to another planet in the Solar System*

For many missions it is possible, if needed, to put the spacecraft into Safe Mode, where it is ‘parked’ in a stable position with all non-essential systems switched off. For Mars Express however, an extended time in this mode would not be very safe at the moment.

Mars Express is currently in an eclipse season, where in every orbit the spacecraft passes through the shadow of Mars, preventing power from being generated by the solar arrays.

As the spacecraft passes into the martian shadow, it relies on batteries to supply it with power and on internal heaters to keep it warm. To ensure the 17-year-old batteries are not too deeply discharged during this period, the team needs to adjust the heaters before, during and after each eclipse to keep vital spacecraft systems at the right temperature to function. This activity reduces the overall heater power consumption by around 30%.

Mars Express uses star trackers and gyros to determine which direction it is pointing in. The gyros are now very old and are switched off most of the time to preserve their remaining runtime. The software update performed in 2018 is working well and has made it possible to dramatically increase how long the life remaining in the units can be stretched out.

The gyros do need to be switched on once per day for routine maintenance activity (to ‘dump’ momentum from the reaction wheels, which allow the spacecraft to change its attitude, the direction in which it points). This isn’t possible without the ability to communicate with and command the mission – another reason that Safe Mode isn’t an option for the old martian orbiter.

*An unusually quiet Mars Express control room*

This all requires people on hand to guide Mars Express back into the light. In Safe Mode, none of these commands would get on board. This means the load on the batteries would increase and crucially the gyros would remain on, eating into their remaining lifetime.

At present, the team is happy to report that routine science operations are continuing through a reduced presence on site, and adaptation of the operating procedures to fit this difficult situation.

In a case the team were completely unable to get on site, they have generated an emergency commanding timeline which prepares the spacecraft for eclipses, avoids pointing the star trackers at Mars, turns the gyros on and off as required and performs other tasks to keep the spacecraft safe.

*A few stunning views of the Red Planet, captured by Mars Express*

This, if activated would keep the spacecraft safe for about three weeks. As each week passes the team adds another week of safety commands to the plan, so there are always three weeks’ worth of commands available to be sent to the spacecraft if required.

However, as there is limited space on board the spacecraft to store commands, the team has had to remove any commands that are not necessary to keep the spacecraft safe.

Unfortunately, this includes the commands that would be needed to operate the science instruments. If this emergency plan is activated, science observations would therefore be suspended for the duration.

*Launched in June 2003, ESA’s Mars Express has been studying all aspects of the Red Planet for more than 15 years*

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In response to the Covid-19 outbreak, people across the globe are being asked to work from home where possible in order to limit personal contact and reduce the further spread of the infection.

As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

But what implications does this have for the 17-year-old Mars Express spacecraft, currnently in orbit around the Red Planet?

Mars Express is currently in an eclipse season, where in every orbit the spacecraft passes through the shadow of Mars, preventing power from being generated by the solar arrays.

At present, the team is happy to report that routine science operations are continuing through a reduced presence on site, and adaptation of the operating procedures to fit this difficult situation.

However, as there is limited space on board the spacecraft to store commands, the team has had to remove any commands that are not necessary to keep the spacecraft safe.

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Avoiding space smashes while social distancing

In response to the coronavirus outbreak, people across the globe are being asked to work from home where possible in order to limit personal contact and reduce the further spread of the infection.

As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

But what implications does this have for the daily work being done to protect space missions from colliding with each other, or orbiting remnants of space debris?

Our planet is now surrounded by thousands of fragments of space junk – defunct satellites or fragments created in previous collisions and explosions.

Satellites in Earth orbit, flying in relatively busy space highways, must be continually protected from hazardous space debris.

On average, ESA performs two collision avoidance manoeuvres per year for each Earth mission it flies. Such manoeuvres divert spacecraft into a safe orbit, ensuring they do not collide with functioning or non-functioning satellites or debris.

Throughout the coronavirus outbreak, work to protect Europe’s space missions will continue.

“We consider the continued monitoring of any potential collisions, and performing manoeuvres to avoid these, one of our highest priorities,” explains Holger Krag, Head of Space Safety.

“We will be able to protect our spacecraft from collisions remotely, even in any much degraded situation with a minimum of personnel and equipment present on site.”

Fortunately, minimising the number of people on site doesn’t mean minimising operations. Close approaches between spacecraft and debris will continue being monitored, and if action is required, those that are needed are ready to come in.

High-velocity impact sample shows the damage that can be created by small, but fast moving objects – a small sphere of aluminum travelling ~ 6.8 km per sec and a block of aluminum 18 cm thick

What is a collision avoidance manoeuvre?

When a satellite looks like it will come too close for comfort with another object, either another functioning spacecraft or space debris, mission teams send the commands to get it out of the way.

For a typical satellite in low-Earth orbit, hundreds of alerts are issued every week. For most, the risk of collision decreases as the week goes by and more information is gathered about the orbits of the objects in question.

For the situations that remain risky, hours are spent analysing the distance between the two objects, their likely positions in the future, uncertainties in observations and therefore in calculations and ultimately the probability of collision.

Predicted near-collision between ESA’s Aeolus satellite and a satellite in the SpaceX, Starlink constellation in September 2019

If the probability is greater than typically 1 in 10,000, the work of various teams is needed to prepare a collision avoidance manoeuvre and upload the commands to the satellite.

The manoeuvre must be verified to ensure it will have the expected effect, and doesn’t for example bring the spacecraft closer to the object or even in harm’s way of another object.

‘Space debris – a journey to Earth’, Produced for the 7th European Conference on Space Debris, 18-21 April 2017

As more and more satellites are being launched into Earth orbit, we will soon have more active satellites in orbit than have been launched before in the history of spaceflight.

Read more about past examples of collision avoidance:

Automating collision avoidance

ESA is developing a collision avoidance system that will automatically assess the risk and likelihood of in-space collisions, improve the decision making process on whether or not a manoeuvre is needed, and may even send the orders to at-risk satellites to get out of the way.

As these intelligent systems gather more data and experience, they will get better and better at predicting how risky situations evolve, meaning errors in decision making would fall as well as the cost of operations.

Find out more, here.

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As of Monday 16 March, the majority of staff and contractors working at ESA mission control began doing just this.

But what implications does this have for the daily work being done to protect space missions from colliding with each other, or orbiting remnants of space debris?

Our planet is now surrounded by thousands of fragments of space junk – defunct satellites or fragments created in previous collisions and explosions.

Satellites in Earth orbit, flying in relatively busy space highways, must be continually protected from hazardous space debris.

Throughout the coronavirus outbreak, work to protect Europe’s space missions will continue.

“We consider the continued monitoring of any potential collisions, and performing manoeuvres to avoid these, one of our highest priorities,” explains Holger Krag, Head of Space Safety.

“We will be able to protect our spacecraft from collisions remotely, even in any much degraded situation with a minimum of personnel and equipment present on site.”

What is a collision avoidance manoeuvre?

When a satellite looks like it will come too close for comfort with another object, either another functioning spacecraft or space debris, mission teams send the commands to get it out of the way.

If the probability is greater than typically 1 in 10,000, the work of various teams is needed to prepare a collision avoidance manoeuvre and upload the commands to the satellite.

The manoeuvre must be verified to ensure it will have the expected effect, and doesn’t for example bring the spacecraft closer to the object or even in harm’s way of another object.

As more and more satellites are being launched into Earth orbit, we will soon have more active satellites in orbit than have been launched before in the history of spaceflight.

Read more about past examples of collision avoidance:

Automating collision avoidance

Find out more, here.

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Unidentified Fiery Object!

Help find a meteorite?

On 18 January 2020 at 16:44 UTC (17:44 local time), two fireball cameras in ESA’s FRIPON camera network spotted a stream of light in the skies above northwestern Germany. The trajectory of the ball of fire suggests a small meteorite could have landed in the vicinity of Oldenburg.

The fireball streams across top-left of the image, taken by a FRIPON camera at the University of Oldenburg

Fireballs are caused as small asteroids strike Earth’s atmosphere, entirely or almost entirely burning up due to friction, and appearing in the sky brighter than the planet Venus.

Meteor entering the Earths Atmosphere over Italy in the Dolomites, 2017. More info, here

The object that impacted Earth on this occasion is estimated to have been just 10-40 cm in diameter, before it entered the atmosphere. The observed fireball flew in a south to north direction, west of the German city of Cloppenburg and heading towards the nearby city of Friesoythe.

It is possible that one, or even several small pieces survived the journey through our protective atmosphere and reached the ground as meteorites. Such meteorites however will be just a few grams in mass and difficult to find.

Were you in the region?

If you spotted the event, you can report it directly to the International Meteor Organization using the form available at vsw.imo.net, or send an email to the space environment group at the University of Oldenburg, via björn.poppe@uol.de or gerhard.drolshagen@uol.de. (If you think you have found a meteorite, Björn and Gerhard would also love to hear about it!).

Check out the path the fireball took, as observed from Earth. Data comes from Francois Colas of the FRIPON network

FRIPON fireball network

The FRIPON network consists of 150 fisheye cameras working together to plot the course of meteorites entering Europe’s skies, supporting efforts to retrieve fresh-fallen meteorites for study. It started in France, lead by the IMCCE-Paris Observatory, MNHN-National History Museum and GEOPS-Paris Sud University. Data are stored and processed at OSU-Pyheas-Marseille.

On this occasion, two cameras spotted the speedy fireball, one located at the Cosmos Sterrenwacht observatory in the Netherlands, and the other at the University of Oldenburg in Germany.

Finding NEMO

The detection and analysis of fireball events like this is also part of the NEMO (NEar real-time impact MOnitoring) project. NEMO aims to provide information on objects hitting Earth’s atmosphere becoming bright fireballs, using data gathered via social media reports across Europe and worldwide, as well as observations from the FRIPON fireball network.

Only a few days ago, a test version of the software was installed at ESA’s mission control and operations centre in the Space Safety Office.

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Help find a meteorite?

Fireballs are caused as small asteroids strike Earth’s atmosphere, entirely or almost entirely burning up due to friction, and appearing in the sky brighter than the planet Venus.

Were you in the region?

FRIPON fireball network

On this occasion, two cameras spotted the speedy fireball, one located at the Cosmos Sterrenwacht observatory in the Netherlands, and the other at the University of Oldenburg in Germany.

Finding NEMO

Only a few days ago, a test version of the software was installed at ESA’s mission control and operations centre in the Space Safety Office.

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Rolling coverage: Brace for hypothetical asteroid impact

Setting the scene: Planetary Defense Conference 2019

Every two years, asteroid experts from across the globe come together to pretend an asteroid impact is imminent. During these week-long impact scenarios, participants don’t know how the situation will evolve know from one day to the next but must make plans based on the daily updates they are given.

For the first time, ESA will be live tweeting the hypothetical impact scenario from the heart of the Planetary Defense Conference (PDC) in Washington DC – so you’ll find out the ‘news’ as the experts do. What will they do? What would you do?

“The first step in protecting our planet is knowing what’s out there”, says Rüdiger Jehn, ESA’s Head of Planetary Defence.

“Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or minimise the damage it does on the ground”.

This year’s asteroid – 2019 PDC

The scene has been set for this year’s hypothetical impact scenario. Although realistic, is it is completely fictional and does NOT describe an actual asteroid impact.

— An asteroid was discovered on 26 March, 2019, and has been given the name “2019 PDC” by the Minor Planet Center.

— Initial calculations suggest the orbit of 2019 PDC will bring it within 7.5 million km of Earth’s orbit. (Or, within 0.05 AU of Earth’s orbit. One AU is the mean distance between the Sun and Earth, equal to 149 597 870.7 km).— 2019 PDC is travelling in an eccentric orbit, extending 2.94 AU at its farthest point from the Sun (in the middle of the main asteroid belt), and 0.94 AU at its closest. It completes one full orbit around the Sun every 971 days (2.66 years). See its orbit in more detail, here: https://go.nasa.gov/2vkZyT5

— The day after 2019 PDC is discovered, ESA and NASA’s impact monitoring systems identify several future dates when the asteroid could hit Earth. Both systems agree that the asteroid is most likely to strike on 29 April 2027 – more than eight years away – with a very low probability of impact of about 1 in 50 000.

— When it was first detected, asteroid 2019 PDC was about 57 million km from Earth, equal to 0.38 Astronomical Units. It was travelling about 14 km/s, and slowly getting brighter.

— As observations continue, the likelihood of an impact in 2027 increases. Three weeks after discovery, after observations were paused during the full Moon (and reduced visibility), the chance of impact has risen to 0.4 percent – a chance of 1 in 250.— Very little is known about the asteroid’s physical properties. From its brightness, experts determine that the asteroid’s mean size could be anywhere from 100-300 meters.

— Asteroid #2019PDC continued to approach Earth for more than a month after discovery, reaching its closest point on 13 May. Unfortunately, the asteroid was too far away to be detected, and it is not expected to pass close to Earth until 2027 – the year of impact.

— As astronomers continued to track #2019PDC, the chance of impact continued to rise. By April 2019, the first day of the Planetary Defence Conference, the probability of impact rises to 1%.

Follow @esaoperations on Twitter for live coverage of the conference, and find daily updates on the asteroid impact scenario here, beginning on Monday 29 April.

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Setting the scene: Planetary Defense Conference 2019

“The first step in protecting our planet is knowing what’s out there”, says Rüdiger Jehn, ESA’s Head of Planetary Defence.

“Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or minimise the damage it does on the ground”.

This year’s asteroid – 2019 PDC

The scene has been set for this year’s hypothetical impact scenario. Although realistic, is it is completely fictional and does NOT describe an actual asteroid impact.

— An asteroid was discovered on 26 March, 2019, and has been given the name “2019 PDC” by the Minor Planet Center.

— When it was first detected, asteroid 2019 PDC was about 57 million km from Earth, equal to 0.38 Astronomical Units. It was travelling about 14 km/s, and slowly getting brighter.

— As astronomers continued to track #2019PDC, the chance of impact continued to rise. By April 2019, the first day of the Planetary Defence Conference, the probability of impact rises to 1%.

Follow @esaoperations on Twitter for live coverage of the conference, and find daily updates on the asteroid impact scenario here, beginning on Monday 29 April.

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Royal Astronomical Society award and 18 years of Cluster

The four Cluster satellites are now old enough to vote and have a driver’s license in most countries of the world, in spite of the fact that they have, in fact, been happily ‘driving’ themselves well above most countries for the last 18 years.

Today’s post was contributed by Cluster Spacecraft Operations Manager Bruno Texira de Sousa. On 11 January, the UK’s Royal Astronomical Society awarded its 2019 Group Achievement Award to the Cluster Science and Operations Teams. Follow the mission in Twitter via @esa_cluster.

Cluster images the Earth South pole (South Africa is visible between the clouds) with the VMC separation camera Credit: ESA

Beginnings

The Cluster mission got off to a very rough start in 1996, with the first quartet being destroyed along with their rocket during the unsuccessful Ariane 5 maiden flight from Kourou, in French Guiana. After being rebuilt and re-launched, in the summer of 2000, the satellites have gone on to exceed everyone’s most optimistic predictions, and they continue to produce the most amazing observations and data on the fundamental physics of the space between the Sun and Earth.

The rate of scientific publications from Cluster data has not significantly lowered over the years and in fact, with the launch of newer missions like NASA’s Magnetospheric Multiscale (MMS) mission, the Van Allen Probes mission and Themis, or China’s Double Star, Cluster’s relevance has, if anything, only become more important.

From Cluster’s unique vantage point, it is possible today to do complementary science observations together with all these other missions, enriching the quality of the data, and the quality of results for all.

Innovation

If there is one feature that can define the Science Operations Workgroup of Cluster, it’s that they never felt complacent or happy to just do more of the same. Every extension of the mission up to now has been carefully planned to address new and exciting science targets. And from the mission operations side, all our efforts have been toward ensuring the success of those campaigns by carefully managing flight control challenges and optimising resources.

It seems almost paradoxical that the older the spacecraft, and the fewer the resources available to keep the mission flying, the more data are produced. In fact, 2018 was the year the mission produced the largest-ever volume of data with the least amount of ground-station tracking time, one of the unavoidable costs to flying any mission.

Orbital evolution – steady changes in the four satellites’ pathways around Earth – has been a major contribution to this, and with the apogee (the point in a satellite’s orbit when it is highest above Earth) at its lowest, we have benefitted from a favourable configuration. In addition, constant improvement of our weekly planning and scheduling coupled with innovative techniques like ‘Multiple Satellite per Aperture’ (allowing two or more satellites to be tracked simultaneously with the same ground station – we are the first mission to use it routinely at ESA), and better management of resources, has allowed for additional optimisation.

Middle-age aches and pains

From 2008 to 2012, the laws of physics and celestial mechanics dictated that the spacecraft were experiencing a nasty dip into the Van Allen belts, tyre-shaped belts of highly energetic electrons and protons that are trapped by Earth’s magnetic field. This caused solar array degradation, leading to power loss and, eventually, the on-board batteries failed and had to be permanently shut down. The loss of power meant that heating had to be sparse and the high-power amplifier had to be sacrificed, thus leading to an increase in the time required for downloading data.

In 2011, the spacecraft engineers faced an exhausting year with almost uninterrupted eclipses (when our satellites receive no sunlight so generate no power) every single orbit, requiring enormous effort to manage powering down and then switching on and reconfiguring everything back to full operational status. With all hands available doing shifts to cope with the workload, little time was left to implement improvements.

More innovation

But necessity is the mother of creativity and soon the engineers got around to automating many of these command-intensive tasks. Further, simplifications have meant that we have reduced the time required to recover the four spacecraft from four to one hour per spacecraft. Today, when everything goes smoothly, which is almost always, we can finish the task in two hours doing a pair of spacecraft at one time, needing just four or five mouse clicks.

The last seven years have seen Cluster change from a mission that had been fighting against adversity to survive, to a mission at the forefront of optimisation and automation of operations. This has been in great measure possible due to a team of well-practiced and smart engineers, who were already highly motivated to achieve that transformation, as a result of a culture and philosophy put in place by my predecessor, Jürgen Volpp.

With the advent of automation and the pressure to optimise resources, less manual work has led, over the years, to a reduction in the size of the team available to conduct real-time operations. From an initial pool of nine spacecraft controllers covering 24 hrs/day, year-round operations in the control room plus three analysts to cover our database management and mission-planning needs, we have gradually but systematically reduced to four spacecraft controllers and no analysts, with part of the work simplified, automated or shared among the also-trimmed pool of spacecraft operations engineers, which now totals six, including the Spacecraft Operations Manager.

With the reduction in staffing, we improved shift and station planning to optimise the collocation of controllers and ground contacts. We’ve also extended automation to allow for ‘hands-off’ operations when no staffing of the consoles was possible. Automation has also been progressively built-in to some of our recurrent anomaly alerts, whose signature we can identify, and therefore provide a systematic and timely reaction.

The original Clusterweb timeline still heavily in use to support station planning Credit: ESA

Tools, tools

Clusterweb has been one of the tools emerging from the creativity and skills of the Cluster team that has helped to dramatically improve planning and fleet supervision. It began its evolution in 2009.

In 2016, the team opted for a full-scale re-engineering of the tool, resulting in a new, modern and highly configurable timeline plotting engine, now called OPSWEB, currently in use by five other teams.

Operations teams have always prototyped any small tools they needed. What makes this development stand out is the scale and scope of development achieved. It wasn’t just another tool done in Excel or Java by a trainee; instead, a professional approach was used, making full use of Scrum, a cutting-edge design technique, combined with enlarging the development team through small voluntary contributions across the organisation (at its peak, seven people were working on it simultaneously) and supported by a state-of-the-art development and integration environment, a flexible and modular architecture and a modern technology stack. The result thus far achieved, is, by all standards, remarkable and on par with the best to be found in industry.

The new OPSWEB timeline engine as configured for Cluster Credit: ESA

Incubating expertise

Engineers who have worked with Cluster operations, either because they have had to deal with the complex eclipse operations or because they have had to help sort out the radiation- and age-related equipment glitches, have traditionally become very comfortable dealing directly with the spacecraft, and have evoled into experts who tackle problems in an autonomous and responsible way. They have also become very pro-active in improving the overall operations setup, whether by improving flight procedures, automation scripts or deploying new tools.

This has meant that, over the years, Cluster operations alumni have found their way into the newest and most complex missions flown by ESA at the ESOC mission control centre, like Bepi, ExoMars and Juice. Several have also found their way into key positions at Eumetsat and in new space companies.

Cluster has become a ‘school for operations’ at ESOC, and managing the turnover of the team and the propagation of the needed skills, experience and mind-set has been a tremendous challenge. At the same time, we continue striving to produce ever bigger and more complete sets of science data.

It is, therefore, perhaps no big wonder that earlier this month, the UK’s Royal Astronomical Society, when honouring the extraordinary scientific output of this mission, also emphasised the role of operations in the society’s recent announcement of the 2019 Group Achievement Award to the Cluster mission.

A mission that not so long ago was at risk of being discontinued has instead continued shining as a backbone data provider for the geophysics community and a role model for effective and efficient mission operations.

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Cluster images the Earth South pole (South Africa is visible between the clouds) with the VMC separation camera Credit: ESA

Beginnings

Innovation

Middle-age aches and pains

More innovation

The original Clusterweb timeline still heavily in use to support station planning Credit: ESA

Tools, tools

The new OPSWEB timeline engine as configured for Cluster Credit: ESA

Incubating expertise

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Mars Express — from worry, to water

In 2004, a year after Europe’s first mission to Mars was launched, the flight dynamics team at ESA’s operations centre encountered a serious problem. New computer models showed a worrying fate for the Mars Express spacecraft if mission controllers continued with their plans to deploy its giant MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) radar.

Artist’s impression of Mars Express. Credit: Spacecraft image credit: ESA/ATG medialab; Mars: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

MARSIS main antenna. Credit: Universität der Bundeswehr – München

This extremely sensitive radar instrument spans 40 metres across once fully extended, making it longer than a Space Shuttle orbiter and was built with the direct intention of finding water beneath Mars’ surface. By sending out a series of chips between 1.8 and 5.0 Mhz in ‘subsurface’ mode would scour the red planet for any signs of water anywhere down to a depth of a few kilometres. A secondary ‘ionosphere’ mode at 0.1 to 5.4 Mhz surveyed the electrical conductivity of the Martian upper atmosphere.

Two ‘radar booms’, 20-metre long hollow cylinders, 2.5 centimetres in diameter, and one 7-metre boom, were folded up in a box like a concertina. Once the box was opened, all of the stored elastic energy from the glass fibre booms would be released, a little like a jack-in-the-box, and they would lock into a straight line.

New and updated computer models, however, showed that these long rods would swing back and forth upon release with an even greater amplitude than previously thought, potentially coming into close contact with the delicate parts of the Mars Express body.

Deployment was postponed

Artist’s impression of MARSIS Boom 1 deployed. Credit: ESA

Plans were made to get the spacecraft in a ‘robust’ mode before the deployment of each boom and while the glass fibre cylinders were extended. After each deployment the control team would conduct a full assessment of the spacecraft, taking up to a few days, before moving onto the next phase.

The first deployment began on 4 May 2005 with one of the two 20-metre ‘dipole’ booms, and flight controllers at ESA’s operations centre quickly realised something wasn’t quite right. 12 out of 13 of the boom segments had ‘snapped’ into place, but one, possibly number 10, was not in position.

Deployment of the second and third booms was postponed

Further analysis showed that prolonged storage in the cold conditions of outer space had affected the fibreglass and Kevlar material of the boom. What could be done to heat it up?

MARSIS boom 2 deployment begins. Credit: ESA, CC BY-SA 3.0 IGO.

Enter: the Sun. Mission teams decided to swing the 680 kg spacecraft to a position that would allow the Sun to heat the cold side of the boom. It was hoped that as the cold side expanded in the heat, the unlocked segment would be forced into place.

One hour later, as contact was reestablished at 04:50 CET on 11 May, detailed analysis showed all segments had successfully locked in place and Boom 1 was successfully deployed!

Following the rollercoaster rollout of the first antenna, flight controllers spent some time mulling over the events. A full investigation ensued, lessons were learnt, and plans were put in place to prevent the same irregularity from taking place in the next two deployments.

By 14 June 2005, operators felt confident that they, and Mars Express, were ready to deploy the second boom. At 13:30 CEST the commands were sent.

This time, Mars Express was set into a slow rotation to last 30 minutes during and after the release of the second 20-metre boom. The rotation was planned so that all of the boom’s hinges would be properly heated by the Sun before, during, and after deployment.

MARSIS fully deployed. Credit: ESA, CC BY-SA 3.0 IGO

Just three hours later and the first signs of success reached ground control, showing that Mars Express had properly re-oriented itself and was pointing towards Earth, transmitting data.

The data confirmed that the spacecraft was working with two fully and correctly deployed booms, and their deployment had not caused any damage to the spacecraft.

Not long after, the third boom was deployed, and the full MARSIS setup was complete on Mars Express.

Let the science begin

Just four months later, and ESA was reporting on the radar’s activities. MARSIS radar scientists were collecting data about a highly electrically conducting layer – surveyed in sunlight. They were also continuing the laborious analysis of data in the search for any possible signs of underground water, in a frozen or liquid state.

MARSIS prospecting for water. Credit: ESA

Radar science is based on the detection of radio waves, reflected at the boundaries between different materials. Each material interacts with light in a different way, so as the radio wave crosses the boundary between different layers of material, an echo is generated that carries a sort of ‘fingerprint’, providing information about the kind of material causing the reflection, including clues to its composition and physical state.

The Red Planet

Like Earth, Mars has two ice caps covering its poles, and early attempts to measure the composition of these regions suggested the northern cap could be composed of water ice, while the southern cap is made up of carbon dioxide ice.

Map of the south pole at Mars, derived from OMEGA infrared spectral images. Credit: ESA/OMEGA.

Later observations by the OMEGA instrument on board Mars Express suggested the southern cap was in fact composed of a mixture of carbon dioxide and water. However, it was only with the arrival of Mars Express that scientists were able to obtain direct confirmation for the first time that water ice is present at the south pole.

MARSIS, the first radar sounder ever sent to orbit another planet, revealed that both polar ice caps are up to 3.5 km thick, each with a core of water ice that is covered by a layer of carbon dioxide ice, centimetres to decimetres thick.

A remarkable discovery

Mars Express detects water buried under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ASI/Univ. Rome; R. Orosei et al 2018

On 25 July 2018, fifteen years after its launch, it was confirmed that data from years of Mars Express’ observations were telling us something remarkable. Hidden beneath Mars’ south pole is a pond of liquid water, buried under layers of ice and dust.

The presence of liquid water at the base of the polar ice caps had long been suspected, but until now evidence from MARSIS had remained inconclusive. It has taken the persistence of scientists working with this subsurface-probing instrument over years, developing new techniques in order to collect as much high-resolution data as possible to confirm such an exciting conclusion.

Kasei Valles mosaic. Credit: ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO

Liquid water cannot survive on the surface of Mars, as the low atmospheric pressure causes it to evaporate in a matter of hours. But this has not always been the case. Evidence for the Red Planet’s watery past is prevalent across its surface in the form of vast dried-out river valley networks and gigantic outflow channels clearly imaged by orbiting spacecraft. Orbiters, together with landers and rovers exploring the martian surface, also discovered minerals that can only form in the presence of liquid water.

Over the course of the Red Planet’s 4.6 billion year history, its climate has vastly changed, meaning scientists today have to look for water underground. We now know for certain that under its surface Mars harbours ancient masses of liquid water.

Mars’ northern polar ice cap. Credit: NASA/JPL-Caltech/MSSS

Kept in a liquid state by the vast pressures from glaciers above, it is thought that this water is also a briny solution. The presence of salts on Mars could further reduce the melting point of water, keeping it liquid even at below-freezing temperatures.

Dmitri Titov, ESA’s Mars Express project scientist: “This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability.”

So congratulations to everyone involved in this incredible discovery, and thank you to the flight controllers at ESA’s operations centre in Darmstadt whose dedication and ingenuity 14 years ago made possible what we know today.

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Artist’s impression of Mars Express. Credit: Spacecraft image credit: ESA/ATG medialab; Mars: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

MARSIS main antenna. Credit: Universität der Bundeswehr – München

Deployment was postponed

Artist’s impression of MARSIS Boom 1 deployed. Credit: ESA

Deployment of the second and third booms was postponed

Further analysis showed that prolonged storage in the cold conditions of outer space had affected the fibreglass and Kevlar material of the boom. What could be done to heat it up?

MARSIS boom 2 deployment begins. Credit: ESA, CC BY-SA 3.0 IGO.

One hour later, as contact was reestablished at 04:50 CET on 11 May, detailed analysis showed all segments had successfully locked in place and Boom 1 was successfully deployed!

By 14 June 2005, operators felt confident that they, and Mars Express, were ready to deploy the second boom. At 13:30 CEST the commands were sent.

MARSIS fully deployed. Credit: ESA, CC BY-SA 3.0 IGO

Just three hours later and the first signs of success reached ground control, showing that Mars Express had properly re-oriented itself and was pointing towards Earth, transmitting data.

The data confirmed that the spacecraft was working with two fully and correctly deployed booms, and their deployment had not caused any damage to the spacecraft.

Not long after, the third boom was deployed, and the full MARSIS setup was complete on Mars Express.

Let the science begin

MARSIS prospecting for water. Credit: ESA

The Red Planet

Map of the south pole at Mars, derived from OMEGA infrared spectral images. Credit: ESA/OMEGA.

A remarkable discovery

Kasei Valles mosaic. Credit: ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO

Mars’ northern polar ice cap. Credit: NASA/JPL-Caltech/MSSS

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Impacting the ‘dark side’

The Moon is as old as the Earth, at about 4.5 billion years of age. For as long as there have been creatures on Earth able to observe it, the Moon has been there to be seen.

The dimpled Moon. Credit: ESA/Silicon Worlds/Daniele Gasparri

Detlef during a Desert RATS ‘spacewalk’, 2011. Credit: ESA/W. Carey

In 450 BC the ancient Greek philosopher Anaxagoras realised that the Moon does not shine with its own light, instead bathing in the reflected glory of the radiant Sun. As early as 150 BC, the Greek philosopher ‘Seleucus of Seleucia’ considered the Moon to be the cause of tides on Earth.Today, we have landed on the Moon, leaving footprints, a feather from the famous “hammer-feather drop” experiment, even a cast golden olive branch lies amongst the countless other worldly possessions still orbiting Earth. More importantly we even brought lunar samples back home to study and explore. So, what more is there to know?

For a thousand years people have described witnessing mysterious, fleeting phenomena across the face of the Moon, and once we had the tools to observe its surface, we saw evidence of a history of high-energy bombardment in the countless craters and shock waves that blanket it.

It was only in 1997 that the first systematic attempts were made to identify impact flashes, and today ESA is one of a few organisations continuing to study these ‘transient lunar phenomena’.

We spoke to Detlef Koschny, ESA planetary scientist and co-manager of the near-Earth object section of ESA’s Space Situational Awareness programme, who is currently studying these impacts, finding out about the bits of space that keep smashing into our Moon…

Q: First of all, what is a lunar ‘impact flash’, and why are you interested?

Two lunar flashes light up darkened Moon, 17 – 18 July, 2018. Credit: J. Madiedo / MIDAS

There are many small, but fascinating and ancient pieces of material travelling at high speed through space, and I am interested in the smallest of them. My main research interest is cosmic dust, meteors, fireballs, and other minor bodies in the Solar System — particularly asteroids!

When a small asteroid or meteoroid hits the Moon, part of the energy is converted to light — and this is what we see as an ‘impact flash‘.

Q: How are you involved in studying these fleeting flashes?

Rosetta’s view of the Moon, 2007. Credit: ESA

I am involved in two projects whose main focus is lunar micrometeoroid impacts. NEOLITA was launched by ESA at at the National Observatory of Athens in February, 2015. It aims to determine the distribution and frequency of small near-earth objects (NEOs) by monitoring lunar impact flashes, using the 1.2m Kryoneri telescope located in the Northern Peloponnese, in Greece.

Like all other impact flash monitoring programmes, NEOLITA only observes impact flashes only on the dark side of the Moon — note that the dark side is entirely different to the far side!

Unlike the ‘far side’ of the Moon which always faces away from Earth (and has a slightly different surface) the dark side refers to any part of the Moon that is not currently illuminated by the Sun, although — such as during a crescent Moon — it may still be facing Earth.

Then there is LUMIO — the Lunar Meteoroid Impact Observer. ESA set a challenge last year (2017) — “Imagine sending a spacecraft the size of an airline cabin bag to the Moon – what would you have it do?” and LUMIO was one of the two successful answers!

The largest lunar flash ever recorded, September 2013. Credit: J. Madiedo / MIDAS

The plan is that LUMIO would circle over the far side of the Moon to detect bright impact flashes during the lunar night, mapping meteoroid bombardments as they occur!

Q: How common are they, and what can they tell us?

NELIOTA sees one flash on average every 2-3 hours of continuous observation time, so from that we can calculate that there are really are several per day.

The light flash lets us estimate the size and velocity of the object that hit it, and from this we can better understand how many of these objects hit the Moon, and how often. This is of particular interest to future astronauts that spend any time on the Moon! But this information also helps us understand the general environment that Earth and the Moon find themselves in — with some scaling factors to account for the different gravity of the two bodies, we can use the lunar data as a proxy for impacts into Earth’s atmosphere.

Differences between the near and far sides of the Moon. Credit: ESA

Q: How do impacts on the Moon differ from those on Earth?

Earth’s atmosphere protects us from objects smaller than about 20 metres, so to get impact craters on our surface we need even bigger asteroids that can survive, intact, before they reach the ground. On the Moon everything reaches the ground, because it doesn’t have an atmosphere. This means that we get ‘hypervelocity’ impact craters even from very small objects that impact it.

Q. Why are impacts on the dark side of the Moon important to study? Are they any different?

Impacts are the same everywhere on the Moon, but it is much easier to see the flash of light they cause if they occur on the dark, rather than illuminated, side. This is for the same reason that we can only see faint stars only at night and not during day — the contrast is just not high enough.

Q: Will the July 2018 eclipse provide any useful insights into lunar impacts?

2015 Super Moon eclipse. Credit: ESA/CESAR

Normally we don’t observe during the Full Moon, because the complete side facing us is illuminated and is too bright. In principle it would be possible to search for impact flashes during the eclipse, as the Moon is in the shadow of the Earth — statistically speaking we may see one impact during the eclipse!

2015 Super Moon eclipse. Credit: ESA/CESAR

As for special results — some people measure the redness or darkness of the eclipse to deduce something about Earth’s atmosphere. The reason why the eclipsed Moon is red is because while in principle it is in the shadow of the Earth, the red sunlight still manages to pass through Earth’s atmosphere and is indirectly scattered onto the Moon. So, by looking at the intensity of the red Moon we could deduce something about our atmosphere. But as for our work on lunar flashes, eclipses don’t really give new science results — but are something beautiful to enjoy.

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The Moon is as old as the Earth, at about 4.5 billion years of age. For as long as there have been creatures on Earth able to observe it, the Moon has been there to be seen.

The dimpled Moon. Credit: ESA/Silicon Worlds/Daniele Gasparri

Detlef during a Desert RATS ‘spacewalk’, 2011. Credit: ESA/W. Carey

It was only in 1997 that the first systematic attempts were made to identify impact flashes, and today ESA is one of a few organisations continuing to study these ‘transient lunar phenomena’.

Q: First of all, what is a lunar ‘impact flash’, and why are you interested?

Two lunar flashes light up darkened Moon, 17 – 18 July, 2018. Credit: J. Madiedo / MIDAS

When a small asteroid or meteoroid hits the Moon, part of the energy is converted to light — and this is what we see as an ‘impact flash‘.

Q: How are you involved in studying these fleeting flashes?

Rosetta’s view of the Moon, 2007. Credit: ESA

Like all other impact flash monitoring programmes, NEOLITA only observes impact flashes only on the dark side of the Moon — note that the dark side is entirely different to the far side!

The largest lunar flash ever recorded, September 2013. Credit: J. Madiedo / MIDAS

The plan is that LUMIO would circle over the far side of the Moon to detect bright impact flashes during the lunar night, mapping meteoroid bombardments as they occur!

Q: How common are they, and what can they tell us?

NELIOTA sees one flash on average every 2-3 hours of continuous observation time, so from that we can calculate that there are really are several per day.

Differences between the near and far sides of the Moon. Credit: ESA

Q: How do impacts on the Moon differ from those on Earth?

Q. Why are impacts on the dark side of the Moon important to study? Are they any different?

Q: Will the July 2018 eclipse provide any useful insights into lunar impacts?

2015 Super Moon eclipse. Credit: ESA/CESAR

2015 Super Moon eclipse. Credit: ESA/CESAR

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Capture the Moon, Mars, and the ISS

For those in the right position, July 2018 is proving to be a particularly pleasing month for gazing heavenwards. On Thursday 27, the longest total lunar eclipse of the 21st century will take place. For 1 hour and 43 minutes our nearest neighbour will be totally shrouded in Earth’s shadow, appearing to turn a spectacular red-brown colour.

But July has even more to offer, because this month Mars will be brighter in the sky than at any point since 2003, as it passes relatively near Earth at ‘just’ 57.6 million km away.

And as these two unique events take place, the International Space Station (ISS) continues to orbit Earth — capturing spectacular images, carrying out vital research, and appearing periodically above us in the skies.

To celebrate, ESA has a challenge:

Mars and the Moon from the @Space_Station by @Astro_Alex.
Challenge: can you take all three – #Mars, #Moon, Space Station – in one picture? Bonus points if you include the lunar eclipse.
Reply to this tweet with (a link to) your picture!
More info: https://t.co/e8AdxQtmtF pic.twitter.com/KpPc9hQyLJ

— Human Spaceflight (@esaspaceflight) July 17, 2018

So, how likely is it to capture the Moon, Mars and an ISS transit in one picture over the coming week?

We asked Miguel Perez Ayucar, leader of Rosetta Science Operations and of the Planning Group at the European Space Astronomy Centre…

“Mars and the Moon will be quite close together in the sky in the next days (see graph below), so they are an easy target for cameras. On the night of the 27th, they will reach their closest separation at an angular distance less than 10 degrees. But note, Mars and the Moon are still several moon diameters apart, so any image with both targets in the same frame will not contain much detail on Mars, which will appear as a beautiful, reddish, big dot.

The International Space Station passes over the same longitude roughly every 1.5 hours, and it is always possible to get a picture during its orbit from somewhere on Earth. Where it will appear, and when that will be on Earth? That is more tricky…

The ideal conditions happen after dusk or before dawn, when the ISS is still in sunlight (not in Earth’s shadow cone). The ideal locations therefore are regions close to the ‘dawn-dusk terminator’. And of course the ISS has to fly over your head at that moment.

To be able to capture the ISS, Moon and Mars in a single shot, they should be close in the sky (to be able to use normal camera lenses, not a fisheye). The closer they are the better, to adjust your zoom and get better resolution of the Moon’s surface (mainly) and Mars’ disk. For the night of the 27th, Mars and the Moon will be beautifully visible in the early night sky, to the South – South-East. For observers in Europe, to get all three objects in the same sky region means that your observing latitude must be higher than the ISS ground track, but not so far North that you have a dark night sky.

The 27th July blood Moon eclipse takes place between 19:30 to 21:13 UTC (the total eclipse in umbra crossing), and luckily the ISS is predicted to pass over Europe during this period…

The ISS passes over Europe on 27th July 2018 around moon eclipse. Image from www.isstracker.com

For certain parts of southern Europe, such as Spain, Italy and Central Europe, and for ESAC, in Madrid (image below), the ISS will only cross the night sky at low elevations in the northern sky, so opposite the Moon and Mars. In central Europe the pass is still overhead, such as for ESTEC in The Netherlands (image below), so it will be difficult to have them in the same picture.

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location, ESAC, Madrid. Credit: heavens-above free software (heavens-above.com)

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location, ESTEC, The Netherlands. Credit: heavens-above free software (heavens-above.com)

As we move to northern parts of Europe, the three objects are together closer in the sky. For example in Inverness, at 23:10 UTC, it should be possible to capture them with less than 30 degrees of angular separation. Of course at this point Mars and the Moon will still be very low on the horizon so the observer should check the horizon mask to avoid obstructions and preferably be in high grounds.

The ISS sky chart for 27th July 2018, pass around 23:10 UTC. Location Inverness, Scotland. Credit: heavens-above free software (heavens-above.com)

A similar geometry is achieved from Riga, Latvia, at 21:33, just after the total umbra and still in the penumbra phase of the eclipse.

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location Riga, Latvia. Image from heavens-above free software (heavens-above.com)

So it is possible the see all of them in the same picture, even during the eclipse phase. You might even get Saturn in it, as well!” The night sky is just beautiful at this moment. Except Mercury, all the brightest planets are visible together after dusk: (from West to East) Venus, Jupiter, Saturn and Mars. One can easily draw the ecliptic line by moving your arm from one to the other!”

The bright planets as seen on 27th July 2018. Location ESAC, Madrid. Image from Stellarium free software (stellarium.org)

We would love to see any pictures taken showing the Moon, Mars and the International Space Station in one shot – even better if you manage to get all three during the lunar eclipse. Send your images to ESA’s social media channels, as a Facebook message to ESA, with hashtag #youresa on Instagram, or as a reply to the pinned tweet on @esaspaceflight. Provide as much background to how you took the picture as you can. The best three entries will be eligible to win exclusive prizes.

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But July has even more to offer, because this month Mars will be brighter in the sky than at any point since 2003, as it passes relatively near Earth at ‘just’ 57.6 million km away.

To celebrate, ESA has a challenge:

Mars and the Moon from the @Space_Station by @Astro_Alex.
Challenge: can you take all three – #Mars, #Moon, Space Station – in one picture? Bonus points if you include the lunar eclipse.
Reply to this tweet with (a link to) your picture!
More info: https://t.co/e8AdxQtmtF pic.twitter.com/KpPc9hQyLJ

— Human Spaceflight (@esaspaceflight) July 17, 2018

So, how likely is it to capture the Moon, Mars and an ISS transit in one picture over the coming week?

We asked Miguel Perez Ayucar, leader of Rosetta Science Operations and of the Planning Group at the European Space Astronomy Centre…

The 27th July blood Moon eclipse takes place between 19:30 to 21:13 UTC (the total eclipse in umbra crossing), and luckily the ISS is predicted to pass over Europe during this period…

The ISS passes over Europe on 27th July 2018 around moon eclipse. Image from www.isstracker.com

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location, ESAC, Madrid. Credit: heavens-above free software (heavens-above.com)

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location, ESTEC, The Netherlands. Credit: heavens-above free software (heavens-above.com)

The ISS sky chart for 27th July 2018, pass around 23:10 UTC. Location Inverness, Scotland. Credit: heavens-above free software (heavens-above.com)

A similar geometry is achieved from Riga, Latvia, at 21:33, just after the total umbra and still in the penumbra phase of the eclipse.

The ISS sky chart for 27th July 2018, pass around 21:30 UTC. Location Riga, Latvia. Image from heavens-above free software (heavens-above.com)

The bright planets as seen on 27th July 2018. Location ESAC, Madrid. Image from Stellarium free software (stellarium.org)

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Satellite studying Earth’s diminishing ice swerves to avoid collision

CryoSat. Credit: ESA/P. Carril

On Monday 9 July, 2018, engineers based at the European Space Operations Centre (ESOC) in Germany made the decision to alter the path of the CryoSat satellite, preventing a potentially fatal collision between it and an ‘unknown object’. For the second time this year the risk of collision was deemed high enough to give the satellite instructions to get out of the way.

CryoSat is ESA’s mission dedicated to measuring the thickness of polar sea ice and monitoring changes in the ice sheets blanketing Greenland and Antarctica. Flying at an altitude of just over 700 km and travelling from pole to pole, Cryosat keeps us informed about an often cited ‘early casualty’ of global warming, Earth’s ice.

The first warning of trouble came about a week before the event from the Joint Space Operations Center (JSpOC) in the US, informing ESA’s Space Debris Office that a potential collision was on the horizon.

Time of close approach: Monday 9 July, 04:24 UTC.

3D collision plot. Credit: Spacecraft Conjunction Assessment and Risk Front-end (SCARF)

“We received the first CDM (Conjunction Data Message) from JSpOC on 2 July 2018 at 08:02 UTC. At this point the chance of collision was still below our threshold of 1 in 10 000. By 5 July 2018, 23:00 UTC, the probability had climbed above the threshold and we informed the mission the next morning.” describes Vitali Braun, Space Debris Engineer at ESA’s Space Debris Office.

“It is a somewhat different feeling than usual work, but there’s only a small amount of stress or concern. The teams involved know exactly what to do and everyone is very professional.”

CryoSat operations team waiting for updates from the satellite at the Earth Observation Control Room at ESOC

So the warning was passed from the Space Debris office to the team operating CryoSat at the Earth Observation Mission Control Room.

Giuseppe Albini, CryoSat Spacecraft Operations Engineer recounts: “The object was approaching from behind and below CryoSat, and even though its orbit is monitored and tracked, its origin is unknown. We had one lunchtime meeting with the Space Debris Office, Flight Dynamics, the Flight Control Team and the Mission Manager, Tommaso Parrinello. Considering the collision probability exceeded 1/10000, we decided to prepare the manoeuvre, and as this was happening over the weekend, cancel our plans!”

Getting CryoSat to safety

On Sunday the commands were sent to CryoSat, on Monday, 50 minutes before the potential collision, its thrusters fired, and because of the swift action of many experienced and dedicated teams the chance of collision dropped from 1 in 10 000 to 1 in 1 000 000.

By firing its thrusters CryoSat increased its speed, and in so doing increased its ‘orbital energy’, pushing it into a higher orbit around the Earth. Instead of a distance of 14-metres between the two objects at their closest point, CryoSat passed more than 120-metres above the unknown object, or ‘chaser’.

Chasers might be operational satellites, dead satellites, spent rocket parts, mission-related debris e.g. lens covers, payload adapters, and the most common source, explosion and collision fragments.

Back to work

CryoSat. Credit: ESA/AOES

After it was confirmed that CryoSat had successfully avoided collision, the operations team began preparations to get it back into an orbit that would allow it to continue its vital work.

“The collision avoidance manoeuvre performed early on Monday raised the orbit of CryoSat outside the optimal altitude. We are currently preparing the commands that will implement a second manoeuvre, ensuring CryoSat is able to satisfy its scientific mission in the weeks to come,” explained Elia Maestroni, CryoSat-2 Spacecraft Operations Manager.

With these commands CryoSat again fired its thrusters, but this time in the opposite direction, slowing it down by 3.043 cm/s and so lowering its orbit.

By Thursday, CryoSat was back at work.

The problem of junk

Artist’s impression of space debris around Earth. Credit: ESA/ID&Sense/ONiRiXEL, CC BY-SA 3.0 IGO

None of this would have been possible without the dedication and experience of the teams involved, but an event like this still comes at some cost. Every time CryoSat fires its thrusters it uses some of its fuel, ultimately shortening the length of its mission.

This is CryoSat’s second Collision Avoidance Manoeuvre of 2018 and the 14th since it launched in 2000, and according to Vitali Braun, events like this are becoming more common:

“about 50% of all alerts and Collision Avoidance Manoeuvres at ESOC are due to fragments left over from two particular events: the anti-satellite test conducted by the Chinese military in 2007, which destroyed the former weather satellite Fengyun-1C and left a huge debris cloud behind, and the collision of two intact spacecraft, Iridium-33 and Cosmos-2251, in 2009. One could say that we have doubled the amount of chaser objects since 2007 and thus also the frequency of manoeuvres like this. This only applies however to our satellites in Low Earth Orbit, like the Sentinels, CryoSat and Swarm.”

By the end of 2017, 19 894 bits of space junk were known to be circling our planet with a combined mass of 8000 tones, and unfortunately these numbers are increasing.The goal now is to remove debris from space, at the same time as preventing any more getting there in the first place. ESA has taken a leading role in this mission, with the creation of the Space Debris Office, which comes under its Space Situational Awareness Programme, and the Clean Space initiative.

For more information on the problem of debris, check out ESA’s 2017 report on space junk.

Space debris GIF. Credit: ESA, CC BY-SA 3.0 IGO

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CryoSat. Credit: ESA/P. Carril

Time of close approach: Monday 9 July, 04:24 UTC.

3D collision plot. Credit: Spacecraft Conjunction Assessment and Risk Front-end (SCARF)

“It is a somewhat different feeling than usual work, but there’s only a small amount of stress or concern. The teams involved know exactly what to do and everyone is very professional.”

CryoSat operations team waiting for updates from the satellite at the Earth Observation Control Room at ESOC

So the warning was passed from the Space Debris office to the team operating CryoSat at the Earth Observation Mission Control Room.

Getting CryoSat to safety

Chasers might be operational satellites, dead satellites, spent rocket parts, mission-related debris e.g. lens covers, payload adapters, and the most common source, explosion and collision fragments.

Back to work

CryoSat. Credit: ESA/AOES

After it was confirmed that CryoSat had successfully avoided collision, the operations team began preparations to get it back into an orbit that would allow it to continue its vital work.

With these commands CryoSat again fired its thrusters, but this time in the opposite direction, slowing it down by 3.043 cm/s and so lowering its orbit.

By Thursday, CryoSat was back at work.

The problem of junk

Artist’s impression of space debris around Earth. Credit: ESA/ID&Sense/ONiRiXEL, CC BY-SA 3.0 IGO

This is CryoSat’s second Collision Avoidance Manoeuvre of 2018 and the 14th since it launched in 2000, and according to Vitali Braun, events like this are becoming more common:

For more information on the problem of debris, check out ESA’s 2017 report on space junk.

Space debris GIF. Credit: ESA, CC BY-SA 3.0 IGO

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