Could a Disabled Spy Satellite Pose a Threat to Earth?

  • Thread starter Thread starter Astronuc
  • Start date Start date
  • Tags Tags
    Falling Sky
AI Thread Summary
A large U.S. spy satellite has lost power and is expected to re-enter Earth's atmosphere in late February or early March, posing potential hazards due to its hydrazine fuel. Government officials are monitoring the situation and considering options to mitigate risks, including the possibility of shooting it down, although specifics remain classified. The satellite's uncontrolled descent raises concerns about where debris might land, with historical precedents indicating that most re-entries occur harmlessly over oceans or uninhabited areas. There are debates about the implications of using a missile to destroy the satellite, as this could create additional debris and alter the trajectories of remaining pieces. The decision to act is partly influenced by the satellite's sensitive technology and the potential dangers posed by its hazardous materials.
  • #51
nesp said:
Impressive, not often we get to see $100 billion being blown up. Note the different velocities of the fragments coming off. It's the ones that get injected into slightly higher orbits that may hang around a while.
That's true, if by "higher orbits" you mean "higher apogees". The maximum perigee height of any debris particle will be given by the altitude of the intercept, neglecting secondary collisions or maybe explosions of little hydrazine snowballs.
 
Physics news on Phys.org
  • #52
belliott4488 said:
That's true, if by "higher orbits" you mean "higher apogees". The maximum perigee height of any debris particle will be given by the altitude of the intercept, neglecting secondary collisions or maybe explosions of little hydrazine snowballs.

Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's. Of course, at orbital velocities of around 8 km/s, the effect of a collision with a "small" piece can still be serious, even for a small m the m*v^2 gets pretty large.
 
  • #53
the bad thing is that even if you find (or get hit by) a small piece of this thing, I don't think you can legally keep it
 
  • #54
nesp said:
not often we get to see $100 billion being blown up...
Did you mean $100 million? The expended SM-3 missile cost about $10 million, the overall effort inc'l software, relocation of ships and other assets, etc about $40-$60 million.

The satellite itself probably cost around $1 billion.
 
  • #55
rewebster said:
the bad thing is that even if you find (or get hit by) a small piece of this thing, I don't think you can legally keep it
Man, a piece of this thing comes through my roof - I'm framing it and hanging it on the wall!
 
  • #56
It's going to hard to frame a four foot diameter steel hollow ball and hang it
 
  • #57
I understand that the debris field will pass over Canada first. It should make for an interesting light show for the next couple of days.
 
  • #58
nesp said:
Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's. Of course, at orbital velocities of around 8 km/s, the effect of a collision with a "small" piece can still be serious, even for a small m the m*v^2 gets pretty large.
Yeah - what you said. I was actually surprised when I started thinking about it, since initially I kind of guessed that for a given delta-v, the ones with higher flight path angles would go higher, and thus live longer, but it ain't so. A FPA of positive theta is the same as one of negative theta, in terms of apogee and perigee heights. It's the ones that produce a zero FPA that last the longest - i.e. the Hohmann Part 1, as you described it.
 
  • #59
we need photos of anything you find
 
  • #60
rewebster said:
It's going to hard to frame a four foot diameter steel hollow ball and hang it
Ha ha - luckily, they're now saying that the biggest chunk is no larger than a football - although they didn't specify if that was a US or Euro "football". ;-)
 
  • #61
joema said:
Did you mean $100 million? The expended SM-3 missile cost about $10 million, the overall effort inc'l software, relocation of ships and other assets, etc about $40-$60 million.

The satellite itself probably cost around $1 billion.

No, I meant Billion with a "B." To start with, $1B would hardly cover the overruns on this satellite. If the following report is true, this satellite was part of a $10B program, including $4-5B in overruns.

http://blog.wired.com/defense/2008/02/that-satellite.html

That's the cheap part. Now, let's count the cost of the missile defense program, of which the SM-3 is just a part. That individual $10M missile would not be there if not for the program that brought it into existence, and $100B is probably a lowball estimate.
 
  • #62
chemisttree said:
I understand that the debris field will pass over Canada first. It should make for an interesting light show for the next couple of days.
I think that was for the first orbit after the intercept. By now it's had time to do many revs, and has probably passed over most of the planet's surface, either on ascent or descent.
 
  • #63
I bet:

they don't hit that tank with the hydrazine

and most of the spy satellite will end up falling on land someplace
 
  • #64
rewebster said:
I bet:

they don't hit that tank with the hydrazine

and most of the spy satellite will end up falling on land someplace
So you think their claims of nothing larger than a football surviving are just plain lies? I guess it wouldn't be the first time, but there are a lot of people with insight into this who could catch them out if they were lying.
 
  • #65
nesp said:
Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's.
The missile hit the satellite at an altitude of 130 miles, so the perigee of any chunks sent into a higher orbit will still be 130 miles. 130 miles is quite deep in the atmosphere. Vehicles with circular orbits at 130 miles fall within a day or so. Elliptical orbits take a bit longer, but not years. The Pentagon quotes a max of 40 days for all of the debris to re-enter.
 
  • #66
D H said:
The missile hit the satellite at an altitude of 130 miles, so the perigee of any chunks sent into a higher orbit will still be 130 miles. 130 miles is quite deep in the atmosphere. Vehicles with circular orbits at 130 miles fall within a day or so. Elliptical orbits take a bit longer, but not years. The Pentagon quotes a max of 40 days for all of the debris to re-enter.
No, that's true only for debris ejected with a vertical flight path angle of 90 deg. (i.e. horizontally). Any other angle and perigee will be lower; I think that's the reason for the claims. I believe the imparted delta-v is distributed approximately evenly in direction about the incoming velocity vector.
 
  • #67
I think they should wait until it actually starts entering the atmosphere to shoot at it---it would show a lot better on the news
 
  • #68
belliott4488 said:
No, that's true only for debris ejected with a vertical flight path angle of 90 deg. (i.e. horizontally). Any other angle and perigee will be lower; I think that's the reason for the claims. I believe the imparted delta-v is distributed approximately evenly in direction about the incoming velocity vector.

I agree that's the reason for the claims, but I was referring to those pieces ejected with additional velocity along the parth of the original orbit. There probably are not many such pieces, in comparison with the total, but some will obtain additional velocity for the same reason that someone shooting a bullet at, say, a piece of concrete, will have some concrete fragments fly back into their face. The movie shows what appears to be a pressure sphere exploding, probably the outgassing hydrazine. That pressure will itself impart positive delta v to any pieces in front of it.

DH, I don't have the chart in front of me, but if you find a chart for decay of elliptical orbit debris, you will find that even at 130 mile perigee there are orbits that won't decay for over a year, those with apogees in the hundred of miles. Doesn't take more than a couple of km/s extra to get those apogees.
 
  • #69
CaptainQuasar said:
Oh well. There goes an arms race with China.

Not necessarily, they pay for their weapons development by selling us consumer goods.

We pay for ours by borrowing money from China.:rolleyes:
 
  • #70
nesp said:
DH, I don't have the chart in front of me, but if you find a chart for decay of elliptical orbit debris, you will find that even at 130 mile perigee there are orbits that won't decay for over a year, those with apogees in the hundred of miles. Doesn't take more than a couple of km/s extra to get those apogees.

That's correct. The perigee altitude will barely change until the orbit becomes circular. Then the orbit will start to decay.

Any maneuver, including maneuvers performed by the atmosphere, primarily affect the opposite side of the orbit.

Assuming an even distribution of material, there will be very few pieces of debris with a perigee of 130 miles. The overwhelming majority will have lower perigees and higher apogees.
 
  • #71
Not necessarily, they pay for their weapons development by selling us consumer goods.
We pay for ours by borrowing money from China
We could sell them weapons - that would balance out!
 
  • #72
I just saw the video on the news of the missile and explosion----didn't they say it was a non-armed missile?-----it didn't look like it
 
  • #73
rewebster said:
I just saw the video on the news of the missile and explosion----didn't they say it was a non-armed missile?-----it didn't look like it
Just shows what a good healthy dose of kinetic energy can do ...
 
  • #74
nesp said:
I agree that's the reason for the claims, but I was referring to those pieces ejected with additional velocity along the parth of the original orbit. There probably are not many such pieces, in comparison with the total, but some will obtain additional velocity for the same reason that someone shooting a bullet at, say, a piece of concrete, will have some concrete fragments fly back into their face. The movie shows what appears to be a pressure sphere exploding, probably the outgassing hydrazine. That pressure will itself impart positive delta v to any pieces in front of it.

DH, I don't have the chart in front of me, but if you find a chart for decay of elliptical orbit debris, you will find that even at 130 mile perigee there are orbits that won't decay for over a year, those with apogees in the hundred of miles. Doesn't take more than a couple of km/s extra to get those apogees.
Yeah ... escape velocity at that altitude is only around 11 - 12 km/sec, so if the impact could deliver 3 km/sec delta-v, you know apogee would be way up there.
 
  • #75
BobG said:
That's correct. The perigee altitude will barely change until the orbit becomes circular. Then the orbit will start to decay.

Any maneuver, including maneuvers performed by the atmosphere, primarily affect the opposite side of the orbit.

Isn't that how atmospheric braking is done?
 
  • #76
nesp said:
Isn't that how atmospheric braking is done?
Atmospheric braking usually refers to re-entry, I believe, not orbits. In any case, though, the general rule of thumb is that removing energy at perigee lowers apogee, thus orbits with low perigee (and therefore increased drag compared to the rest of the orbit) tend to become circularized. Once it's circular, then apogee and perigee are effectively the same, and you can lower perigee by removing energy at apogee (actually, at that point you're doing it everywhere along the orbit, but that's the general rule).
 
  • #77
Aerobraking was first used in the movie 2001, but a recent Mars probe used it as well.
 
  • #78
russ_watters said:
Aerobraking was first used in the movie 2001, but a recent Mars probe used it as well.
No kidding? It was also used in the movie "Dark Star", although in that case the astronut surfed into the upper atmosphere on a chunk of space debris ...

(a special prize to the first person who recognizes that obscure reference!)
 
  • #79
I loved Doolittle trying to convince the bomb not to explode
 
  • #80
Shoulda' known this forum would have people who know that movie!:cool:
 
  • #81
I was very young when I saw it in theaters, but I remember seeing it. I had to buy it when it came out on DVD (2010, too)...
...oh oh...I may actually be getting the two of them confused now. It may have been 2010 (2010 was better). I'll be back in 4 hours...

Anyway: http://mars.jpl.nasa.gov/odyssey/mission/aerobraking.html
It was actually named after the story/movie!
http://en.wikipedia.org/wiki/Aerobraking
 
Last edited by a moderator:

Similar threads

News Interview: U.S., Russia still face mutual destruction threat
Replies
14
Views
3K

Hot Threads

Recent Insights

Back
Top