Space Forum / Shuttle / November 2007

Hi,

I downloaded the nice Orbiter Space flight Simulator from
http://orbit.medphys.ucl.ac.uk/orbit.html... some days ago.

My taget is to rendez-vous my vessel (Atlantis) with the ISS. I am
using the cool manual on...

http://smithplanet.com/stuff/orbiter/orbitaloperations.htm

...for that operation.

Thatfore I tried the last two days  to allign and synchronize my
vessel and the ISS...according to the manual I mentioned above. Thats
my current situation:

1) I alligned my orbital plane with that one of the ISS. The RInc is
zero.

2) Then I opened the Orbit MFD, determined and created an intersection
(as it is discribed under Synchronizing orbit- determing an
intersection). I lowered my periapsis sucessfully to that one of the
ISS, that are 6.729 km...

So, now the ISS and my vessel are at the same Alt.

3) Then, and here comes the problem...I got to the part "Synchronizing
our orbits":

I switched to the Sync Orbit MFD (the VInc is still zero) and there is
a DTmin of 1.498 k. Now I want to reduce that figure of course.
Therefore I followed the instructions which say

"If your orbit is larger than the target orbit (the intersection is
your periapsis), then raise your apoapsis (make your orbit even
bigger)

If your orbit is smaller than the target orbit (the intersection is
your apoapsis), then lower your periapsis.

* If you are raising your periapsis, burn prograde at your
intersection (apoapsis).
* If you are lowering your periapsis, burn retrograde at your
intersection (apoapsis).
* If you are raising your apoapsis, burn prograde at your intersection
(periapsis).
* If you are lowering your apoapsis, burn retrograde at your
intersection (periapsis)."

If i understood right my "intersection" is still my periapsis, so I
raised my apoapsis in order not to change my intersection point (per).
Therefore I burned prograde at the per.

The poor result - and this is my REAL problem:

The DTmin decreased just very, very low...but the VInc increases more
and more!

I tried all other possibilities (retrograde at Per; Prograde/
Retrograde at the Apoapsis etc.), the results are all the same: The
DTMin decreases just marginally but the other values (VInc) get worse.

That cant be right...

What I am doing wrong here? How is it possible to reduces DTMin nearly
to zero *without* changing VInc, Alt etc...?

Many thanks for your help!

Kind regards

Susan