9 ms·

Track Europe's falling, 2,000-pound satellite in real-time

55 points by joering2 13y ago

praseodym 13y ago
ESA has more information about the reentry: http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/GOCE_completes_its_mission http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/G...
deletes 13y ago
Original site: http://www.n2yo.com/satellite/?s=34602 http://www.n2yo.com/satellite/?s=34602 The ( ion-driven :) )satellite: http://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_Explorer http://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_... Current altitude: 159.30
- joering2 13y ago
  perhaps its one of my extensions, but this is what I am getting from n2yo site: Connection refused (111) * Connection refused (111)
  - deletes 13y ago
    Same here, the site must be overloaded.
gibybo 13y ago
Anyone know what units the altitude and speed are in? I'm guessing km and km/s but I can't be sure.
- molecule 13y ago
  looks like km/s in the map widget via http://www.n2yo.com/?s=34602 http://www.n2yo.com/?s=34602: SPEED [km/s]: 7.93 SPEED [mi/s]: 4.93
joering2 13y ago
How come they are unable to know precisely where it will hit? Isn't it "just" lots of math to go through?
- gibybo 13y ago
  I'm guessing they don't know exactly how the wind currents are going to change over the course of it's flight.
  - joering2 13y ago
    Yes, however winds would apply only to earth atmosphere. Most of its traction happens above earth atmosphere, right?
    - gibybo 13y ago
      The time it is affected by wind might still be enough to qualify its projected landing location as 'not exact'. Maybe they have a 200 mile radius projection or something. I could also imagine its non-spherical shape might present some challenges predicting its path as it rotates and 'flies' in slightly different directions.
    - sp332 13y ago
      What would cause drag besides the atmosphere?
    - maaku 13y ago
      > Most of its traction happens above earth atmosphere, right? What do you think is pulling it in?
- parham 13y ago
  It might also involve the shape of the satellite
  - bbllee 13y ago
    And its orientation.
iM8t 13y ago
Out of curiosity: will the satellite burn up while falling down or is there a slight possibility that it could crash in a residential area?
- iamshs 13y ago
  They (ESA) said, there is a possibility of some pieces surviving the burn, and affecting 20 sq metres of area.
Xophmeister 13y ago
For the minute-or-two I've been watching, it's actually been going upwards: from about 166km to 170km.
- klodolph 13y ago
  Play more KSP. You learn pretty quick "just because it's going up, doesn't mean it's going to stay there."
  - bbllee 13y ago
    Yeah, hard bounce off the atmosphere trades angular momentum for radial velocity and increases eccentricity, meaning next time you hit the atmosphere is gonna be even worse.
- asdfs 13y ago
  Possibly an eccentric orbit.
- joering2 13y ago
  AFAIU it doesn't go up, per se. Because our planet is not a perfect sphere, but rather one that is squeezed on the Poles, its actually the planet distance itself longer while rotating..
  - simias 13y ago
    There's only a 31km difference between the "lowest" and "highest" surface point on earth so I doubt that's what's going on here. More likely is its orbit eccentric and while it seems to go up it continually loses speed due to the atmosphere slowing it down and its average altitude keeps going down continually (although obviously more when it's close to the periapsis, the point of closest approach).
    - lostlogin 13y ago
      Could you explain that figure to me please? Everest isn't nearly that high, so are you starting at the bottom of a trench? Surely the meaningful low point is the lowest point (be it the sea or some other low point) that the inbound fiery ball could hit?
lelf 13y ago
http://blogs.esa.int/rocketscience/ http://blogs.esa.int/rocketscience/, http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/GOCE_completes_its_mission http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/G...: This morning GOCE was at an altitude of around 160 km. As expected, the drag levels have increased very much, with the average now around 90 mN (milliNewton). Re-entry of GOCE into Earth’s atmosphere is predicted to occur during the night between Sunday and Monday, 10/11 November. Break-up of the spacecraft will occur at an altitude of approximately 80 km. Q: Do we expect any of these to reach the surface? HK: Most of these fragments will completely burn up. A small fraction of the initial spacecraft mass – about 20% or 200kg – is expected to reach ground, distributed across dozens of fragments, spread over a sizable re-entry ground swath. Q: Is there any risk to anyone on ground? HK: The risk to the population on ground will be minute. Statistically speaking, it is 250,000 times more probable to win the jackpot in the German Lotto than to get hit by a GOCE fragment. In 56 years of space flight, no man-made space objects that have re-entered into Earth’s atmosphere have ever caused injury to humans.
- deletes 13y ago
  Hmm.. is that statistic calculated for each individual or for the entire population. The changes are to hit are very low in either case, but there is still a large difference mathematically.
  - maigret 13y ago
    Let's try to get an order of the probability... Let's say the parts land on earth with an an angle of more than 45 degrees. I'd take 1 sqm for each human, understanding the angle would reduce that number. Which makes around 10000 sqkm, counted generously. The earth total surface is around 510 millions sqkm. So that's one in 51000 chances for any human to be hit (calculated high). So quite makes sense that no one was impacted yet, but this seems not impossible as well - of course depending on how many satellites impact earth each year. Not counting that people are often in buildings, but one impact could kill more than 1, etc. Personally, I take this number for negligeable still. It would rather be hard finding anything build by humans killing less people.
mistermann 13y ago
I'd think there'd be somewhat of a chance that parts could break off during reentry which might have a much greater chance of hitting a lower terminal velocity and therefore not burn up, can anyone explain why this doesn't seem to be the case? Is it that the high velocity in the upper atmosphere causes much greater heat and destruction than if it was falling through a more dense atmosphere?
ratpik 13y ago
It is dropping altitude faster (40 metres/sec) as it nears the equator and is moving at almost constant velocity (between 7.89-7.91). Looks like it will continue to slowly spiral around the earth and crash in the Atlantic Ocean/N.America based on simple extrapolation. Except that the it is probably not going to be that simple. Just hit the equator. Alt: 156, Spd: 7.93, Long: 128.8, Lat: 0. Now altitude is increasing again.
- cshimmin 13y ago
  The altitude is rising and falling because the satellite is in an (approximately) elliptical orbit around Earth. Go play you some Kerbal Space Program! :)

55 points by joering2 13y ago

ESA has more information about the reentry: http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/GOCE_completes_its_mission http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/G...

deletes 13y ago

Original site: http://www.n2yo.com/satellite/?s=34602 http://www.n2yo.com/satellite/?s=34602 The ( ion-driven :) )satellite: http://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_Explorer http://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_... Current altitude: 159.30

joering2 13y ago
perhaps its one of my extensions, but this is what I am getting from n2yo site: Connection refused (111) * Connection refused (111)
- deletes 13y ago
  Same here, the site must be overloaded.

gibybo 13y ago

Anyone know what units the altitude and speed are in? I'm guessing km and km/s but I can't be sure.

molecule 13y ago
looks like km/s in the map widget via http://www.n2yo.com/?s=34602 http://www.n2yo.com/?s=34602: SPEED [km/s]: 7.93 SPEED [mi/s]: 4.93

joering2 13y ago

How come they are unable to know precisely where it will hit? Isn't it "just" lots of math to go through?

gibybo 13y ago
I'm guessing they don't know exactly how the wind currents are going to change over the course of it's flight.
- joering2 13y ago
  Yes, however winds would apply only to earth atmosphere. Most of its traction happens above earth atmosphere, right?
  - gibybo 13y ago
    The time it is affected by wind might still be enough to qualify its projected landing location as 'not exact'. Maybe they have a 200 mile radius projection or something. I could also imagine its non-spherical shape might present some challenges predicting its path as it rotates and 'flies' in slightly different directions.
  - sp332 13y ago
    What would cause drag besides the atmosphere?
  - maaku 13y ago
    > Most of its traction happens above earth atmosphere, right? What do you think is pulling it in?
parham 13y ago
It might also involve the shape of the satellite
- bbllee 13y ago
  And its orientation.

iM8t 13y ago

Out of curiosity: will the satellite burn up while falling down or is there a slight possibility that it could crash in a residential area?

iamshs 13y ago
They (ESA) said, there is a possibility of some pieces surviving the burn, and affecting 20 sq metres of area.

Xophmeister 13y ago

For the minute-or-two I've been watching, it's actually been going upwards: from about 166km to 170km.

klodolph 13y ago
Play more KSP. You learn pretty quick "just because it's going up, doesn't mean it's going to stay there."
- bbllee 13y ago
  Yeah, hard bounce off the atmosphere trades angular momentum for radial velocity and increases eccentricity, meaning next time you hit the atmosphere is gonna be even worse.
asdfs 13y ago
Possibly an eccentric orbit.
joering2 13y ago
AFAIU it doesn't go up, per se. Because our planet is not a perfect sphere, but rather one that is squeezed on the Poles, its actually the planet distance itself longer while rotating..
- simias 13y ago
  There's only a 31km difference between the "lowest" and "highest" surface point on earth so I doubt that's what's going on here. More likely is its orbit eccentric and while it seems to go up it continually loses speed due to the atmosphere slowing it down and its average altitude keeps going down continually (although obviously more when it's close to the periapsis, the point of closest approach).
  - lostlogin 13y ago
    Could you explain that figure to me please? Everest isn't nearly that high, so are you starting at the bottom of a trench? Surely the meaningful low point is the lowest point (be it the sea or some other low point) that the inbound fiery ball could hit?

lelf 13y ago

http://blogs.esa.int/rocketscience/ http://blogs.esa.int/rocketscience/, http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/GOCE_completes_its_mission http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/G...: This morning GOCE was at an altitude of around 160 km. As expected, the drag levels have increased very much, with the average now around 90 mN (milliNewton). Re-entry of GOCE into Earth’s atmosphere is predicted to occur during the night between Sunday and Monday, 10/11 November. Break-up of the spacecraft will occur at an altitude of approximately 80 km. Q: Do we expect any of these to reach the surface? HK: Most of these fragments will completely burn up. A small fraction of the initial spacecraft mass – about 20% or 200kg – is expected to reach ground, distributed across dozens of fragments, spread over a sizable re-entry ground swath. Q: Is there any risk to anyone on ground? HK: The risk to the population on ground will be minute. Statistically speaking, it is 250,000 times more probable to win the jackpot in the German Lotto than to get hit by a GOCE fragment. In 56 years of space flight, no man-made space objects that have re-entered into Earth’s atmosphere have ever caused injury to humans.

deletes 13y ago
Hmm.. is that statistic calculated for each individual or for the entire population. The changes are to hit are very low in either case, but there is still a large difference mathematically.
- maigret 13y ago
  Let's try to get an order of the probability... Let's say the parts land on earth with an an angle of more than 45 degrees. I'd take 1 sqm for each human, understanding the angle would reduce that number. Which makes around 10000 sqkm, counted generously. The earth total surface is around 510 millions sqkm. So that's one in 51000 chances for any human to be hit (calculated high). So quite makes sense that no one was impacted yet, but this seems not impossible as well - of course depending on how many satellites impact earth each year. Not counting that people are often in buildings, but one impact could kill more than 1, etc. Personally, I take this number for negligeable still. It would rather be hard finding anything build by humans killing less people.

mistermann 13y ago

I'd think there'd be somewhat of a chance that parts could break off during reentry which might have a much greater chance of hitting a lower terminal velocity and therefore not burn up, can anyone explain why this doesn't seem to be the case? Is it that the high velocity in the upper atmosphere causes much greater heat and destruction than if it was falling through a more dense atmosphere?

ratpik 13y ago

It is dropping altitude faster (40 metres/sec) as it nears the equator and is moving at almost constant velocity (between 7.89-7.91). Looks like it will continue to slowly spiral around the earth and crash in the Atlantic Ocean/N.America based on simple extrapolation. Except that the it is probably not going to be that simple. Just hit the equator. Alt: 156, Spd: 7.93, Long: 128.8, Lat: 0. Now altitude is increasing again.

cshimmin 13y ago
The altitude is rising and falling because the satellite is in an (approximately) elliptical orbit around Earth. Go play you some Kerbal Space Program! :)