[ATMoB-discuss] Shuttle and ISS pass

[John Boudreau]

Nice shot Al! As with Mike Schexnaydre's similar image, yours shows a reddish tint from the solar panels to the trail of the ISS.

I joined the SatelliteTracker Yahoo Group, where there was some discussion on the recent passes of Atlantis and the ISS after undocking. The group was among a few that questioned the vehicle's order during these passes after undocking. Chuck Shaw is a member of that group, and he's actually the mission director for the next Hubble repair mission---he had described that the order was Atlantis leading the ISS despite what many of us saw. I posted links there to Mike's pass trail image and my webcam shots, describing the view that the ISS had actually lead.

Chuck looked into this with NASA's STS-117 group and we were right! The Shuttle now maneuvers behind and slightly above the ISS after undocking, primarily for a 'Last Inspection' of the nose and leading edge of the wings. This was the 4th flight to do this maneuver, as previous missions thru 2005 undocked and maneuvered ahead of the ISS. The new maneuver also allows less fuel to be used should the need arise to redock with the ISS. When we saw the pass on Wednesday night, Atlantis was about 46 miles behind the ISS and about a mile higher.

---John

P.S.:
Below is Chuck Shaw's original answer to my Yahoo post. He has since checked this out with the STS-117 group and confirmed it:

>>>>>>>>>>>>>>
>>Your note made me go back and double check what I posted a little earlier when
we were talking about which vehicle was in front.

I did not work STS-117, and made a bad assumption that the undocking and sep sequence was what we have used for years with the ISS. Looks like it was
NOT.......

As it turns out, I am told the sep sequence planned for STS-117 had the orbiter
perform three burns to separate from ISS. SEP1 was a 1.5 fps radial up burn
that put the orbiter above and behind ISS. SEP2 was a 1.0 fps posigrade burn
that set the orbiter phasing further back behind ISS for Late Inspection (to
protect possible re-rendezvous, which would be from behind as the original rmdz
was performed). NC5, the last burn of the day, was another 1.0 fps posigrade
burn that caused the orbiter to fall behind ISS faster. Atlantis' orbit was not
much higher than ISS (about 1 nmi, but it is higher).

That would have definitely had the ISS be the leading vehicle when it passed
over!! The new requirement to perform a late inspection of the wing leading
edges and nosecap for micrometeroid damage prior to entry prompted the change to
simplify a re-rndz if they found something that required returning to the ISS. 
At that point they were about 46 miles behind the ISS. Moving at about 5
miles/second, the Shuttle would have been about 9 seconds behind as they flew
over. Being behind the ISS allows the crew to use the same procedures they
used during the original rndz and docking. The final burn that day would have
increased the sep rate and distance once they knew they did not have to return
to the ISS.....

Monday when we are back at work, I will re-confirm that they actually executed
the pre-flight plan as I described (no more assumptions for me!), and if not
I'll update this note.......


My apologies for misleading folks with my earlier post!!!!

Chuck  <<<<<<<<<<<<<
<<<<<<<<<<<<<<<<<<<


----- Original Message ----- 
From: <artakeda2682 at earthlink.net>
To: <atmob-discuss at atmob.org>
Sent: Friday, June 22, 2007 11:39 AM
Subject: Re: [ATMoB-discuss] Shuttle and ISS pass


>I have posted an image of the ISS and the Shuttle Atlantis passing near the Big 
> Dipper from the Clubhouse in Westford on Wed, June 20:
> 
> http://www.atmob.org/gallery/showimage.php?id=609
> 
> I also have an animated GIF using 6 frames of them both moving toward the SE but
> I currently have not way to post them at this time.
> 
> It was a neat event to see.
> 
> Al
> 
> 
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