The Roentgen Satellite (Rosat) is due to come back to Earth at some stage over the weekend - possibly Sunday. Just as for NASA's UARS satellite, which plunged into the atmosphere in September, no one can say precisely when and where Rosat will come in. What makes the redundant German craft's return interesting is that much more debris this time is likely to survive all the way to the Earth's surface. Experts calculate that perhaps as much as 1.6 tonnes of wreckage - more than half the spacecraft's launch mass - could ride out the destructive forces of re-entry and hit the planet.
Another satellite r-entry - Rosat
Another satellite r-entry - Rosat
A German satellite this time.
Re: Another satellite r-entry - Rosat
The Roentgen Satellite (Rosat) re-entered the Earth's atmosphere between 01:45 and 02:15 GMT.
Just as for Nasa's UARS satellite, which plunged into the atmosphere in September, there was high uncertainty about the final moments of Rosat.
But if the timings are correct, any wreckage would probably have dived into the Indian Ocean - although no eyewitness reports have yet come in.
If anything did manage to make landfall, the likely areas to be affected would have been Myanmar and China.
What made the redundant German craft's return interesting was that much more debris was expected to survive all the way to the Earth's surface.
Experts had calculated that perhaps as much as 1.6 tonnes of wreckage - more than half the spacecraft's launch mass - could have riden out the destructive forces of re-entry and hit the planet.
In the case of UARS, the probable mass of surviving material was put at only half a tonne (out of a launch mass of more than six tonnes).
The difference is due to some more robust components on the German space agency (DLR) satellite.
Rosat was an X-ray telescope mission and had a mirror system made of a reinforced carbon composite material. This mirror complex and its support structure were expected to form the largest single fragment in what could have been a shower of some 30 pieces of debris to make it through to the surface.
But again, as was the case with UARS, any Rosat wreckage was strongly tipped to hit the ocean, given that so much of the Earth's surface is covered by water.
Destructive design
UARS' final resting place was tracked to a remote region of the Pacific, north-east of the Samoan islands.
Rosat's operating orbit meant it could have come down anywhere between 53 degrees North and South latitude - a zone that encompasses the UK in the north and the tip of South America in the south.
Future spacecraft sent into orbit may have to meet stricter guidelines that limit the amount of debris likely to fall back on to the planet, but these rules are still some way from being introduced said Prof Richard Crowther, an expert on space debris and adviser to the UK Space Agency.
"Up until now we've designed satellites to survive the harsh environment of space, and we haven't given much thought to designing them for destructive re-entry," he told BBC News.
"But in future, we will have to consider whether we have got this balance right, and perhaps satellites should be designed in such a way that we can ensure more of what comes down is destroyed in the atmosphere and doesn't hit the surface.
"Unfortunately, there is a whole legacy of spacecraft - 50 years of satellites - and we are going to have to put up with this situation for quite some time, I'm afraid."
Science success
Rosat was launched in 1990 to survey the X-ray sky. It mapped more than 100,000 sources of this high-energy radiation. X-rays tend to come from the hottest and most violent parts of the cosmos, such as the regions around exploded stars and the "edges" of black holes.
The spacecraft worked for eight-and-a-half years before its star tracker failed and it could no-longer work out its position and point correctly. It was shut down in February 1999.
Tracking stations will typically witness the uncontrolled return of at least one piece of space debris every day; and on average, one intact defunct spacecraft or old rocket body will come back into the atmosphere every week.
Something the size of Nasa's UARS satellite is seen to enter uncontrolled perhaps once a year.
Much larger objects such as space station cargo ships return from orbit several times a year, but they are equipped with thrusters capable of guiding their dive into a remote part of the Southern Ocean.
Link
Just as for Nasa's UARS satellite, which plunged into the atmosphere in September, there was high uncertainty about the final moments of Rosat.
But if the timings are correct, any wreckage would probably have dived into the Indian Ocean - although no eyewitness reports have yet come in.
If anything did manage to make landfall, the likely areas to be affected would have been Myanmar and China.
What made the redundant German craft's return interesting was that much more debris was expected to survive all the way to the Earth's surface.
Experts had calculated that perhaps as much as 1.6 tonnes of wreckage - more than half the spacecraft's launch mass - could have riden out the destructive forces of re-entry and hit the planet.
In the case of UARS, the probable mass of surviving material was put at only half a tonne (out of a launch mass of more than six tonnes).
The difference is due to some more robust components on the German space agency (DLR) satellite.
Rosat was an X-ray telescope mission and had a mirror system made of a reinforced carbon composite material. This mirror complex and its support structure were expected to form the largest single fragment in what could have been a shower of some 30 pieces of debris to make it through to the surface.
But again, as was the case with UARS, any Rosat wreckage was strongly tipped to hit the ocean, given that so much of the Earth's surface is covered by water.
Destructive design
UARS' final resting place was tracked to a remote region of the Pacific, north-east of the Samoan islands.
Rosat's operating orbit meant it could have come down anywhere between 53 degrees North and South latitude - a zone that encompasses the UK in the north and the tip of South America in the south.
Future spacecraft sent into orbit may have to meet stricter guidelines that limit the amount of debris likely to fall back on to the planet, but these rules are still some way from being introduced said Prof Richard Crowther, an expert on space debris and adviser to the UK Space Agency.
"Up until now we've designed satellites to survive the harsh environment of space, and we haven't given much thought to designing them for destructive re-entry," he told BBC News.
"But in future, we will have to consider whether we have got this balance right, and perhaps satellites should be designed in such a way that we can ensure more of what comes down is destroyed in the atmosphere and doesn't hit the surface.
"Unfortunately, there is a whole legacy of spacecraft - 50 years of satellites - and we are going to have to put up with this situation for quite some time, I'm afraid."
Science success
Rosat was launched in 1990 to survey the X-ray sky. It mapped more than 100,000 sources of this high-energy radiation. X-rays tend to come from the hottest and most violent parts of the cosmos, such as the regions around exploded stars and the "edges" of black holes.
The spacecraft worked for eight-and-a-half years before its star tracker failed and it could no-longer work out its position and point correctly. It was shut down in February 1999.
Tracking stations will typically witness the uncontrolled return of at least one piece of space debris every day; and on average, one intact defunct spacecraft or old rocket body will come back into the atmosphere every week.
Something the size of Nasa's UARS satellite is seen to enter uncontrolled perhaps once a year.
Much larger objects such as space station cargo ships return from orbit several times a year, but they are equipped with thrusters capable of guiding their dive into a remote part of the Southern Ocean.
Link
Re: Another satellite r-entry - Rosat
DARPA considers satellite harvesting
DARPA reports that more than $300 billion worth of satellites are in the geosynchronous orbit, many retired due to failure of one component even if 90% of the satellite works just as well as the day it was launched. DARPA's Phoenix program seeks to develop technologies to cooperatively harvest and re-use valuable components such as antennas or solar arrays from retired, nonworking satellites in GEO and demonstrate the ability to create new space systems at greatly reduced cost. However, satellites in GEO are not designed to be disassembled or repaired, so it's not a matter of simply removing some nuts and bolts, says David Barnhart. 'This requires new remote imaging and robotics technology and special tools to grip, cut, and modify complex systems.' For a person operating such robotics, the complexity is similar to trying to assemble via remote control multiple Legos at the same time while looking through a telescope.
http://www.darpa.mil/NewsEvents/Release ... 10/20.aspx
http://www.darpa.mil/NewsEvents/Release ... 10/20.aspx
Re: Another satellite r-entry - Rosat
Well is it not about that time for a lot of the older satellites orbits to be at re-entry heights??
You are fully capable of deciding your own destiny. The question you face is: which path will you choose?This is something only you can decide-Sarek
Once you have eliminated the impossible, whatever remains, however improbable, must be the truth-Spock
Once you have eliminated the impossible, whatever remains, however improbable, must be the truth-Spock
Re: Another satellite r-entry - Rosat
Maybe they shouldn't be shooting the stoopid things up there in the first place.Egg wrote:You think we'd have a better way of getting them down.
"If you don't think to good, don't think too much." Yogi
Re: Another satellite r-entry - Rosat
Hey, we've accumulated enough trash on the planet, it's long past time that we got started on the rest of the galaxy.
Re: Another satellite r-entry - Rosat
The plan was OK till it started raining gizmos.
"If you don't think to good, don't think too much." Yogi
Re: Another satellite r-entry - Rosat
Well, the gizmos better start raining or there will be so much space junk up there eventually that space travel will be too dangerous. We'll be trapped on planet Earth, and who the hell wants to be stuck on the same planet as republicans forever.lkwalker wrote:The plan was OK till it started raining gizmos.
A giant laser could do the trick:
http://weareallinthegutter.wordpress.co ... own-laser/They also note that a project like this would need international co-operation before it could be built. I thought that this was because it would be a complicated thing to construct, but on closer reading it turns out to be a more fundamental issue. It’s to
…avoid concerns that it is really a weapons system.
Imagine the conspiracies! Move over sissy toy HAARP, this is Teh Illuminati New World Order Death Ray FEMA Dr. Evil Weapon.
Re: Another satellite r-entry - Rosat
Fuckit. There should be a law against shooting these space jalopies into orbit to start with. The world survived nicely without this shit for a billion years.
"If you don't think to good, don't think too much." Yogi