Question Question for our resident STS experts

[slaver0110]

I was testing a new addon in Orbiter for the STS last night, and I began wondering how the stock navigation tools in the simulator measure up to real life.
Here's the scenario:
Shuttle Endeavor launches into a 200km orbit. The launch goes without a hitch, ET separation is routine, and the circularization burn goes perfectly. With the planned orbit established, the spacecraft itself is in perfect running order.
Then, for whatever reason (the reason is irrelevant to the point of the question that I'm leading up to) ALL radio communication between the orbiter and the ground ceases. No voice communication, no computer datalinks, absolutely NO contact with Earth.
Which leads me to my question.
Given these circumstances, would it be possible for the STS Crew to successfully deorbit and land the Shuttle at Edwards (or wherever it was supposed to land)?
The reason I'm asking is that I understand that the Apollo Missions required a LOT of help from the ground, both in the forms of Engineers, tracking, and computer uplinks. I suppose another way to phrase this is, how much "autonomy" did the STS have, as opposed to Apollo?
Of course, the stock navigation tools in Orbiter imply a completely self-contained nav suite.

Cheers!

 

[GLS]

I was testing a new addon in Orbiter for the STS last night, and I began wondering how the stock navigation tools in the simulator measure up to real life.
Here's the scenario:
Shuttle Endeavor launches into a 200km orbit. The launch goes without a hitch, ET separation is routine, and the circularization burn goes perfectly. With the planned orbit established, the spacecraft itself is in perfect running order.
Then, for whatever reason (the reason is irrelevant to the point of the question that I'm leading up to) ALL radio communication between the orbiter and the ground ceases. No voice communication, no computer datalinks, absolutely NO contact with Earth.
Which leads me to my question.
Given these circumstances, would it be possible for the STS Crew to successfully deorbit and land the Shuttle at Edwards (or wherever it was supposed to land)?
The reason I'm asking is that I understand that the Apollo Missions required a LOT of help from the ground, both in the forms of Engineers, tracking, and computer uplinks. I suppose another way to phrase this is, how much "autonomy" did the STS have, as opposed to Apollo?
Of course, the stock navigation tools in Orbiter imply a completely self-contained nav suite.

Cheers!

In that scenario, they had software in laptops that helped them calculate deorbit targets, instead of having ground do it. The problem would most likely be the weather at the landing site... and also no planes on the runway. :shrug:

 

[Urwumpe]

Also, the crew always gets some important data from the ground to help them should this happens in the near future. For example, as part of every executive package:

25
26 NEXT 2 PLS OPPORTUNITIES:
27
28 EDW22 ORB 17 – 1/00:46 SKC 7 230/10P17
29 EDW22 ORB 33 – 2/00:48 SKC 7 220/10P17
30
31

Practically, even without the laptops, the software used for performing the deorbit burns should be capable of calculating a suitable deorbit burn for the primary landing sites.

 

[Thorsten]

Practically, even without the laptops, the software used for performing the deorbit burns should be capable of calculating a suitable deorbit burn for the primary landing sites.

I suppose the main issue would be cross track distance to the landing site - there's no moving map or so in the Shuttle avionics, but assuming that the astronauts know the orbital inclination, can look out and have a map, they should be able to get this okay.

The on-board software can then be used to input serval 'trial' burns based on rules of thumb which result in a predicted range from entry interface to the landing site - by repeating the calculations till an acceptable range is found (there's 1000 miles cross range, so the targeting doesn't have to be super-accurate) the Shuttle can be de-orbited without external help.

One issue is that in this scenario it would not be possible to update the state vector of the inertial navigation system prior to de-orbiting, so the crew would need to anticipate a relatively large correction when other navigation data (TACAN, barometric altitude,...) is available. In the late flights where a GPS is installed, GPS data could be used instead (assuming the GPS receiver is not disabled), this would provide equivalent accuracy.

So it's not a scenario that's particularly desirable for the crew, but if there's no other problems on board, it seems quite possible to de-orbit without any communications with the ground (there would also be normal air traffic radio installed if I remember correctly, so the Shuttle could contact a regular airport ATC and request to clear the runway or contact the coast guard for tranmitting a bail-out location).

 

[Urwumpe]

I suppose the main issue would be cross track distance to the landing site - there's no moving map or so in the Shuttle avionics, but assuming that the astronauts know the orbital inclination, can look out and have a map, they should be able to get this okay.

Well, actually I meant this less magically: The crew always gets a set of the next deorbit opportunities for the current flight day, should any failure make it impossible to get the needed data from ground. As long as the time is correctly entered, using a default PEG4 solution should get a fairly accurate reentry solution.


But yes, cross range targeting could be far less than optimal then, wind conditions and other factors would also be missing.


BTW: The shuttle has a moving map display. But only in OPS1 and only for the Northern Atlantic Ocean. Done with a quite ingenious solution by defining a special drawing command that paints the map (predefined in IDP memory) translated by the current drawing cursor...

 

[Thorsten]

Hm, I understood the question as 'Could the Shuttle theoretically continue the mission for a few days and then de-orbit'.

The question of whether a de-orbit at the next suitable opportunity is possible seems a bit easier, here I agree, entering the time and standard PEG-4 parameters will do the trick just fine.

The shuttle has a moving map display. But only in OPS1 and only for the Northern Atlantic Ocean.

The abort situational awareness (or how it's called)? Yes, know that one (got a feature request to implement it, but haven't done it so far) - so you're quite correct and my statement should have been that the Shuttle has no moving map display that's useful to aim a groundtrack at a landing site for de-orbiting purposes.