Question Shuttle Fleet Rendezvous

[Wolf]

I'm trying to perform all the necessary steps required for th Shuttle to Rendezvous with ISS after MECO (Orbit circularization, NC burns,Ti burns, etc.) as they do in real life but I found no reference or doc's in the NASA website showing how it is actually done (including when the different steps are done in order to reach target and dock on day3)
I've been using Soyuz Guidance MFD following the procedure set up for Soyuz and seems to be working well also for Shuttle Fleet.
Question is: is it what the Shuttle does in real missions? is there any document/tutorial available about the exact procedure they follow from MECO to Rendezvous?

Thanks.

 

[garyw]

Any help?

http://www.nasa.gov/centers/johnson/news/flightdatafiles/foia_archive.html

 

[tblaxland]

I don't know if past missions burn data is available anywhere, but when a mission is on, burn targets can be found along with real time state vectors/elements here: http://spaceflight.nasa.gov/realdat...tions/Post/JavaSSOP/orbit/SHUTTLE/SVPOST.html

 

[Wolf]

Thanks for posting the links guys. I had already checked the NASA Flight data Files but they are a little bit too "specific" (these docs are the ones actually used by Shuttle Crew and look very technical and full of math..too much for me ).
I've found something about rendezvous scheduled burns in the Shuttle Presskits but they just report the different actual burn times.

Anyone knows if there's any easily understandable tutorial or Doc about that (like the one that rjroy has published for the Soyuz missions using Guidance MFD)?

TKS.

 

[Urwumpe]

Thanks for posting the links guys. I had already checked the NASA Flight data Files but they are a little bit too "specific" (these docs are the ones actually used by Shuttle Crew and look very technical and full of math..too much for me ).

The only part that should be really interesting for you (unless you use SSU), are the trajectory plots at the beginning, because they also tell you more about the maneuvers that you want to fly.

Lets go through the rendezvous burns after post insertion (you reached the initial orbit and opened the payload bay:

1. NC1 - Raise the apogee to achieve two things: get closer to the ISS and change the orbit period relative to the ISS so that you can dock at the desired time. If you don't want to calculate much (The formula for timing the rendezvous is at Orbiterwiki), just raise the apogee so you are about 15 km below the ISS. You also want to do this burn opposite of the ISS apogee (at the ISS perigee) - your apsis line is now parallel to the ISS apsis line.
2. Now you have to wait. Check the heat shield and activate payloads.
3. NH - constant delta height burn. you burn at apogee to raise the perigee until the difference between your perigee and the apogee is equal (for example, 15 km).
4. NC - reduce the semimajor axis a bit (by burning retrograde) so you start to get closer to the ISS in a first large step. Should happen at periapsis. You will now drop down relative to the ISS, but also start to move towards it in a half loop.
5. NCC - correct the orbit plane. Should happen close to apogee for effectivity, but more important is intersection with the ISS orbit plane.
6. TI - Terminal intercept. Here you should do math or or use Rendezvous MFD. Sync orbit also works, but is more prone to errors. Do that at periapsis again, burn so that you have rendezvous at apoapsis (Sync orbit dT = 0).
7. MC1, MC2, M3, MC4 - mid course corrections, usually with the RCS, if at all. After the time for MC1, you should also reduce remaining orbit plane errors (OOP) to zero with small pulses of the RCS. All MCx burns have effectively one goal in sync orbit MFD - keep the next apoapsis dT zero. The direction where to burn can best calculated with rendezvousMFD though.
8. Stationkeep at RBar. You should now be between ISS and Earth. Null relative motion and do RPM. You are almost there.
9. Initiate TORVA with small pulses of the RCS.
10. fly in front of the ISS, and null upwards motion. Now you should be able to use RCS for docking. Don't use upwards/downwards RCS at all, you don't need it. You only need to burn forward/backward and left/right for keeping the docking port targeted. You will automatically get closer to the ISS. Slowly.
11. Docking.

If I have something wrong, I am open for corrections.

 

[Wolf]

Thank you Urwumpe. just a few questions:

1) Before NC1 Burn is the Shuttle already on a chase orbit (like the Soyuz does at a 220X220 Km orbit)?

2) Are NCC and PA (Plane Alignment) burns the same thing? (I guess so)

3) Why would you initially raise your orbit (NH burn) up to approximately 15Km below ISS apogee and then reduce your apoapsis again (NC burn) to get closer to ISS? wouldn't it be more (fuel) efficient to just keep your apoapsis lower since the beginning?

4) Is the rendezvous always targeted at ISS apoapsis in STS missions?


I might have said ridiculos things.. Apologies in advance.

Thank you very much for your clarification