Tiangong-1 potential reentry area. Map showing the area between 42.8 degrees north and 42.8 degrees south latitude (in green), over which Tiangong-1 could reenter. Image via ESA CC BY-SA IGO 3.0.
Have you been hearing specific reentry locations for China’s first space station, Tiangong-1, aka Heavenly Palace 1? I heard Michigan at one point, then Wisconsin. Don’t believe these specific predictions. Experts are still saying reentry will take place anywhere between 43 degrees north and 43 degrees south (see map below). At no time will a precise time or location prediction for reentry be possible.
It is possible to narrow down the time of reentry, however. The most recent calculation by Aerospace Corporation (March 22, 2018) is now calling for it to happen around April 1, 2018 plus or minus three days. The European Space Agency (ESA), in its March 23 update, is giving the dates as March 30 to April 3, and still calls these dates highly variable. And, of course, they are subject to change.
You can get a last glimpse of Tiangong-1 – during one of its very last passages across our skies – via the Virtual Telescope Project and Tenagra Observatories. Currently, this live coverage is scheduled for March 28, 2018, starting at 12 UTC (7 a.m. CDT on March 28; translate to your time zone). Virtual Telescope’s page says the time of the event is also subject to change, if Tiangong-1 situation changes quickly. Click here to view online and for updates.
Tiangong-1 was launched in 2011, and, originally, a controlled reentry was planned. Firing the craft’s engines would have enabled controllers to allow the craft to burn up (mostly) over a large, unpopulated region of the South Pacific ocean. Any surviving pieces would have fallen into the ocean. But, in March 2016, the Tiangong-1 space station ceased functioning. Ground teams lost control of the craft, and it can no longer be commanded to fire its engines. It is, therefore, expected to make an uncontrolled reentry … soon.
The spacecraft’s main body is approximately 34 feet (10.4 meters) long.
Reference: here is an illustration of Tiangong-1 by the manufacturer CAST pic.twitter.com/ElrbndsWY4
— Jonathan McDowell (@planet4589) March 7, 2018
ESA has said that Tiangong-1 will “substantially burn up” in Earth’s atmosphere. Will pieces crash to Earth? Possibly. Will they crash in populated areas? It’s not possible to say, but the chances are small that any human being will be harmed, according to a statement from Aerospace, a research organization that advises government and private enterprise on space flight. Aerospace said:
There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the ground. Should this happen, any surviving debris would fall within a region that is a few hundred kilometers in size and centered along a point on the Earth that the station passes over.
Aerospace also warned that the space station might be carrying a highly toxic and corrosive fuel called hydrazine on board.
As of today’s date (March 24, 2018), the spacecraft is at about 134 miles (215 km) altitude. That’s down from 155 miles (258 km) the last time I checked, on March 7. Its orbit is clearly decaying as you can see if you follow the spacecraft’s descent here. The end will come more or less suddenly, due in part to changing conditions in Earth’s upper atmosphere, which is why it’s so inherently unpredictable.
Click here to learn how to see Tiangong-1 before it falls
Tiangong-1 is not designed to withstand reentry, as some spacecraft are. But it will mostly burn up when it falls, due to the extreme heat and friction generated by its high-speed passage through Earth’s atmosphere.
Tiangong 1 predicted reentry, as of March 6, 2018, via ESA.
Tiangong-1’s major goal was to test and master technologies related to orbital rendezvous and docking. One uncrewed and two crewed missions – executed by the Shenzhou (Divine Craft) spacecraft – took place during its operational lifetime. ESA explained:
Following launch in 2011, the Tiangong-1 orbit began steadily decaying due to the faint, yet not-zero, atmospheric drag present even at 300 or 400 km altitude. This affects all satellites and spacecraft in low-Earth orbit, like the International Space Station (ISS), for example.
ESA is updating its forecast for Tiangong-1’s reentry frequently; click here to go to ESA’s updates.
Bottom line: China’s first space station will soon undergo an uncontrolled reentry into Earth’s atmosphere. As of March 22, Aerospace Corporation was predicting April 1 ± 3 days. As of March 23, ESA was predicting March 30 to April 3. At no time will a precise time or location prediction for reentry be possible.
Live, real-time tracking of Tiangong-1 here
from EarthSky https://ift.tt/2Hh9zV9
Tiangong-1 potential reentry area. Map showing the area between 42.8 degrees north and 42.8 degrees south latitude (in green), over which Tiangong-1 could reenter. Image via ESA CC BY-SA IGO 3.0.
Have you been hearing specific reentry locations for China’s first space station, Tiangong-1, aka Heavenly Palace 1? I heard Michigan at one point, then Wisconsin. Don’t believe these specific predictions. Experts are still saying reentry will take place anywhere between 43 degrees north and 43 degrees south (see map below). At no time will a precise time or location prediction for reentry be possible.
It is possible to narrow down the time of reentry, however. The most recent calculation by Aerospace Corporation (March 22, 2018) is now calling for it to happen around April 1, 2018 plus or minus three days. The European Space Agency (ESA), in its March 23 update, is giving the dates as March 30 to April 3, and still calls these dates highly variable. And, of course, they are subject to change.
You can get a last glimpse of Tiangong-1 – during one of its very last passages across our skies – via the Virtual Telescope Project and Tenagra Observatories. Currently, this live coverage is scheduled for March 28, 2018, starting at 12 UTC (7 a.m. CDT on March 28; translate to your time zone). Virtual Telescope’s page says the time of the event is also subject to change, if Tiangong-1 situation changes quickly. Click here to view online and for updates.
Tiangong-1 was launched in 2011, and, originally, a controlled reentry was planned. Firing the craft’s engines would have enabled controllers to allow the craft to burn up (mostly) over a large, unpopulated region of the South Pacific ocean. Any surviving pieces would have fallen into the ocean. But, in March 2016, the Tiangong-1 space station ceased functioning. Ground teams lost control of the craft, and it can no longer be commanded to fire its engines. It is, therefore, expected to make an uncontrolled reentry … soon.
The spacecraft’s main body is approximately 34 feet (10.4 meters) long.
Reference: here is an illustration of Tiangong-1 by the manufacturer CAST pic.twitter.com/ElrbndsWY4
— Jonathan McDowell (@planet4589) March 7, 2018
ESA has said that Tiangong-1 will “substantially burn up” in Earth’s atmosphere. Will pieces crash to Earth? Possibly. Will they crash in populated areas? It’s not possible to say, but the chances are small that any human being will be harmed, according to a statement from Aerospace, a research organization that advises government and private enterprise on space flight. Aerospace said:
There is a chance that a small amount of Tiangong-1 debris may survive reentry and impact the ground. Should this happen, any surviving debris would fall within a region that is a few hundred kilometers in size and centered along a point on the Earth that the station passes over.
Aerospace also warned that the space station might be carrying a highly toxic and corrosive fuel called hydrazine on board.
As of today’s date (March 24, 2018), the spacecraft is at about 134 miles (215 km) altitude. That’s down from 155 miles (258 km) the last time I checked, on March 7. Its orbit is clearly decaying as you can see if you follow the spacecraft’s descent here. The end will come more or less suddenly, due in part to changing conditions in Earth’s upper atmosphere, which is why it’s so inherently unpredictable.
Click here to learn how to see Tiangong-1 before it falls
Tiangong-1 is not designed to withstand reentry, as some spacecraft are. But it will mostly burn up when it falls, due to the extreme heat and friction generated by its high-speed passage through Earth’s atmosphere.
Tiangong 1 predicted reentry, as of March 6, 2018, via ESA.
Tiangong-1’s major goal was to test and master technologies related to orbital rendezvous and docking. One uncrewed and two crewed missions – executed by the Shenzhou (Divine Craft) spacecraft – took place during its operational lifetime. ESA explained:
Following launch in 2011, the Tiangong-1 orbit began steadily decaying due to the faint, yet not-zero, atmospheric drag present even at 300 or 400 km altitude. This affects all satellites and spacecraft in low-Earth orbit, like the International Space Station (ISS), for example.
ESA is updating its forecast for Tiangong-1’s reentry frequently; click here to go to ESA’s updates.
Bottom line: China’s first space station will soon undergo an uncontrolled reentry into Earth’s atmosphere. As of March 22, Aerospace Corporation was predicting April 1 ± 3 days. As of March 23, ESA was predicting March 30 to April 3. At no time will a precise time or location prediction for reentry be possible.
Live, real-time tracking of Tiangong-1 here
from EarthSky https://ift.tt/2Hh9zV9
Aucun commentaire:
Enregistrer un commentaire