USA 193

[Dirkman]

I have been thinking about USA 193 a bit recently and am interested in getting your opinions on it.
Several questions:


1. What is the official story on it's failure and shootdown?
2. Am I correct in thinking that it's said to have failed shortly after launch and was out of contact from control ever since that time?
3. What was it's intended orbit?
4. How close to capacity was the launch vehicle when putting it into orbit?

The last two questions are the ones I'm most interested in, I've done a few calculations and aren't impressed with the results. Hopefully you guys can either confirm what I'm thinking or will come up with different numbers to me and prove me wrong.

(edit) I'm a longtime member, btw. Just changed username and (for the mods) i.p to protect privacy.

 

[Urwumpe]

1. What is the official story on it's failure and shootdown?
2. Am I correct in thinking that it's said to have failed shortly after launch and was out of contact from control ever since that time?
3. What was it's intended orbit?
4. How close to capacity was the launch vehicle when putting it into orbit?

1. Just failure to contact ground control after a few hours in orbit. It is a classified payload, so they won't give too many details in the next decades. Likely is a electrical power system failure, which could mean drained batteries soon after launch. Attitude control failure is more unlikely.
2. yes.
3. very likely exactly 349 km × 365 km × 58.48° - just like it achieved according to amateur measurements. This also fits to the mission of optical reconnaissance.
4. Not really close, when the specs of the satellite are correct. It was a Delta II 7920 launcher, which can put 5100 kg into a 185 km orbit with 28.8° Inclination. When accounting the higher orbit, it's capability is at 4600 kg. When also taking the different inclination into account, it's maximum capability should be 4000- 4200 kg.

The satellite weighted 2300 kg.

 

[Dirkman]

1. Just failure to contact ground control after a few hours in orbit. It is a classified payload, so they won't give too many details in the next decades. Likely is a electrical power system failure, which could mean drained batteries soon after launch. Attitude control failure is more unlikely.

Was that actually confirmed in person by anyone who operated the satellite?

3. very likely exactly 349 km × 365 km × 58.48° - just like it achieved according to amateur measurements. This also fits to the mission of optical reconnaissance.

None of the other recent USA satellites are in orbits anywhere close to that one, and to me it looks like a parking orbit rather than a final orbit. The satellite would always have a very limited lifetime in such a low orbit, which doesn't make any sense.

4. Not really close, when the specs of the satellite are correct. It was a Delta II 7920 launcher, which can put 5100 kg into a 185 km orbit with 28.8° Inclination. When accounting the higher orbit, it's capability is at 4600 kg. When also taking the different inclination into account, it's maximum capability should be 4000- 4200 kg.

Which is exactly what I've thought. How about if we ignore the upper stage, could the lower two+booster stages place the satellite (plus upper stage) into such an orbit as described above?

 

[Urwumpe]

Was that actually confirmed in person by anyone who operated the satellite?

Well, read here:
http://www.aviationweek.com/aw/gene...=Falling Radar Satellite Adds to NRO Troubles

None of the other recent USA satellites are in orbits anywhere close to that one, and to me it looks like a parking orbit rather than a final orbit. The satellite would always have a very limited lifetime in such a low orbit, which doesn't make any sense.

USA-xxx is a generic designation for all anonymous USA satellites without a official operator. If it would have been taken into service with activating all it's payloads and handing the satellite control over from ULA to NRO, it would have gotten the designation NROL-21.

It depends on the actual mission type where the satellite is. Almost all optical satellites operate in low altitudes (<350 km) for having better resolution. That low altitude is the reason why the tiny 2300 kg satellite has a 400 kg hydrazine fuel - for regular reboost maneuvers.

Which is exactly what I've thought. How about if we ignore the upper stage, could the lower two+booster stages place the satellite (plus upper stage) into such an orbit as described above?

No upper stage at all. It was a 7920, with the final 0 meaning, that it was launched without upper stage.

Of course it could deliver such a payload into that Orbit, Boeing would loose lots of money if they write wrong information into their payload planners guides. The next smaller rocket, the 7420 would not be able to deliver such a satellite into such a orbit, as it has not enough payload mass capability.

 

[Dirkman]

USA-xxx is a generic designation for all anonymous USA satellites without a official operator. If it would have been taken into service with activating all it's payloads and handing the satellite control over from ULA to NRO, it would have gotten the designation NROL-21

I was meaning the NRO satellites, the norad database lists NROsats under their USA designation.

It depends on the actual mission type where the satellite is. Almost all optical satellites operate in low altitudes (<350 km) for having better resolution. That low altitude is the reason why the tiny 2300 kg satellite has a 400 kg hydrazine fuel - for regular reboost maneuvers.

The satellite isn't big enough for that mission type. It makes much more sense to have it in a highly elliptical orbit with some dwell time over whatever area they want to focus on, that's what the previous satellites in the series did.

 

[Urwumpe]

The satellite isn't big enough for that mission type. It makes much more sense to have it in a highly elliptical orbit with some dwell time over whatever area they want to focus on, that's what the previous satellites in the series did.

I don't know where you heard this. The later keyhole (for example USA-186) satellites had been as large as Hubble, but usually, optical spy sats are smaller and short lived (for example the "Big Bird" series, operated in a 185 x 277 km orbit in the same plane as USA-193).


Sending them into a highly elliptical orbit is also pretty stupid unless you always want to see the same region every day at the same time - so that the enemy can prepare for it and hide everything interesting. That might have worked in the cold war, but when you don't know which region you want to observe, you are better served with a circular orbit.

 

[simonpro]

I've finally remembered to reply to this topic.
Reading through this brought up one question, how do you tell the difference between the Delta-II with an upper stage and without one? I looked at a few photos and they both look exactly the same.
I'm guessing there's some way to tell them apart though.

 

[Urwumpe]

I'm guessing there's some way to tell them apart though.

It is the numerical type code for the Delta 2 rocket, which makes this possible: "7920"

7 = type of first stage
9 = number boosters
2 = second stage type
0 = upper stage type

 

[simonpro]

No, from looking at the vehicles themselves. I know you can tell them apart on the manifest by the number, but I can't tell the things apart when they're sitting on the pad.

(to be honest I have enough trobule telling different types of launcher apart, let alone different variants of the same launcher).

 

[Urwumpe]

The third stage is inside the payload fairing, so it is pretty hard to notice after the payload fairing get closed.

 

[simonpro]

Fair enough, I'm not just blind then