Sponsor Message:
Military Aviation & Space Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Flight Time To ISS - Why Does It Take So Long?  
User currently offlineFlexo From St. Helena, joined Mar 2007, 406 posts, RR: 0
Posted (6 years 6 months 2 weeks 3 days 12 hours ago) and read 14704 times:

I've been wondering why it takes roughly three days for the Space Shuttle to reach the international space station while there is only about 400 km distance to cover (if the timing is right).

What is it that delays the arrival for so long?

6 replies: All unread, jump to last
 
User currently offlineZANL188 From United States of America, joined Oct 2006, 3525 posts, RR: 0
Reply 1, posted (6 years 6 months 2 weeks 3 days 12 hours ago) and read 14695 times:
Support Airliners.net - become a First Class Member!



Quoting Flexo (Thread starter):
I've been wondering why it takes roughly three days for the Space Shuttle to reach the international space station while there is only about 400 km distance to cover (if the timing is right).

What is it that delays the arrival for so long?

What's the hurry? I'm sure they could do first orbit rendezvous (demonstrated during Gemini and used routinely during Apollo) if there was a need.

The launch window is pretty small to do it on first orbit, a bigger launch window gives more operational flexibility.

Then there are tasks that need to be done before docking - TPS inspection comes to mind.

There's also the small matter of Space Adaptation Syndrome, not smart to attempt a docking (or other hazardous task) while the pilot is vomiting. Best to let them get done vomiting and then dock. This may also be the reason Hans' first spacewalk was delayed on the last mission. Vomiting in your helmet while on a spacewalk, 30 minutes from the nearest airlock, is a bad thing...



Legal considerations provided by: Dewey, Cheatum, and Howe
User currently offlineBHMBAGLOCK From United States of America, joined Jul 2005, 2698 posts, RR: 5
Reply 2, posted (6 years 6 months 2 weeks 3 days 9 hours ago) and read 14639 times:

Thorny answers this question pretty well when covering why night launches and landings are sometimes needed here:

Endeavour Launches And Lands At Night – Why? (by Avi Mar 7 2008 in Military Aviation & Space Flight)



Where are all of my respected members going?
User currently offlineThorny From , joined Dec 1969, posts, RR:
Reply 3, posted (6 years 6 months 2 weeks 3 days 7 hours ago) and read 14598 times:



Quoting ZANL188 (Reply 1):
What's the hurry? I'm sure they could do first orbit rendezvous (demonstrated during Gemini and used routinely during Apollo) if there was a need.

That only works when you launch one orbit after your target... as Gemini did with Agena. Apollo did it at the Moon (LM meeting CSM in orbit) but that was the moon, with 2-hour orbital periods, nearly perfectly equatorial orbits, generally only two or three days after landing, and with the CSM doing "phasing" burns to keep flying over the landing site. This was one problem that Apollo would have faced had far longer missions been planned: the CSM would have needed a lot more fuel to keep "phasing" its orbit to stay in reach of the LM.

After the first orbit, the target drifts farther and farther away from the launch site with each orbit due to precession. When the launch site rotates beneath the target's orbit, the target is now hundreds or thousands of miles away and rendezvous is no longer possible on the first orbit (at least, not with contemporary vehicles limited to standard 200-mile-high orbits like Soyuz and Shuttle.) This can be mitigated somewhat by changing the orbit of the target (speeding up or slowing down by raising or lowering the orbit a little), but there's a limit due to fuel and other factors how much this can be done. So in most cases, rendezvous is going to take a day or two. They often adjust the Station's orbit to make 2 day rendezvous possible (especially for Soyuz and Progress) instead of 3-day rendezvous.


User currently offlineChecksixx From United States of America, joined Mar 2005, 1095 posts, RR: 0
Reply 4, posted (6 years 6 months 2 weeks 3 days 7 hours ago) and read 14595 times:

Simple answer...it has to catch up to the ISS. This takes time as the shuttle doesn't have enough fuel to speed way up and then slow way down in a quicker fashion than the current method.

User currently offlineZANL188 From United States of America, joined Oct 2006, 3525 posts, RR: 0
Reply 5, posted (6 years 6 months 2 weeks 3 days ago) and read 14531 times:
Support Airliners.net - become a First Class Member!



Quoting Thorny (Reply 3):
That only works when you launch one orbit after your target... as Gemini did with Agena.

.. or when you use an appropriate launch window.... but that has lots of unacceptable operational penalties.



Legal considerations provided by: Dewey, Cheatum, and Howe
User currently offlineFlexo From St. Helena, joined Mar 2007, 406 posts, RR: 0
Reply 6, posted (6 years 6 months 2 weeks 2 days 22 hours ago) and read 14505 times:



Quoting BHMBAGLOCK (Reply 2):
Thorny answers this question pretty well when covering why night launches and landings are sometimes needed here:

Endeavour Launches And Lands At Night – Why? (by Avi Mar 7 2008 in Military Aviation & Space Flight)

That topic explained everything indeed! Thanks a lot for the link.


Top Of Page
Forum Index

Reply To This Topic Flight Time To ISS - Why Does It Take So Long?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Military aviation related posts only!
  • Not military related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Why Does Usaf Keep Aircraft For So Long? posted Mon Oct 8 2007 20:46:27 by QFA380
Why So Long For A KC-135R To Get Into The Air? posted Sun Sep 10 2006 02:01:28 by 747400sp
What Took The F-22 So Long To Enter Service? posted Sun Jul 23 2006 20:47:25 by Afrikaskyes
Blackburn Buccaneer: Why Was It So Popular. posted Fri Jun 10 2005 20:08:35 by DIJKKIJK
Why Does The RAF Hang On To The VC-10? posted Sat May 7 2005 01:59:49 by LHMARK
"Now Is The Time To Take Longer Strides"-Rutan CEV posted Fri Dec 10 2004 16:28:28 by N328KF
How Does It Feel To Ride In A Fighter Jet? posted Sat Jul 28 2001 22:49:36 by Climbout
Why Are There No European Long Range Bombers? posted Fri Nov 2 2007 19:39:13 by Wvsuperhornet
RAH-66 Commanche-Why Can't It Replace The Apache? posted Sun May 13 2007 05:12:53 by AirRyan
Why The Military Use So Many 747? posted Wed Feb 14 2007 23:26:35 by 747400sp
How Long Does It Take F-15’s To Reach Mach 1? posted Fri May 26 2006 19:15:47 by Lenbrazil
Why Does Usaf Keep Aircraft For So Long? posted Mon Oct 8 2007 20:46:27 by QFA380
Why So Long For A KC-135R To Get Into The Air? posted Sun Sep 10 2006 02:01:28 by 747400sp
What Took The F-22 So Long To Enter Service? posted Sun Jul 23 2006 20:47:25 by Afrikaskyes
Blackburn Buccaneer: Why Was It So Popular. posted Fri Jun 10 2005 20:08:35 by DIJKKIJK
Why Does The RAF Hang On To The VC-10? posted Sat May 7 2005 01:59:49 by LHMARK
"Now Is The Time To Take Longer Strides"-Rutan CEV posted Fri Dec 10 2004 16:28:28 by N328KF
How Does It Feel To Ride In A Fighter Jet? posted Sat Jul 28 2001 22:49:36 by Climbout
ATV "Edoardo Amaldi" On Its Way To ISS posted Fri Mar 23 2012 11:30:43 by jollo
SpaceX Goes To ISS - COTS2/3 Launch Date posted Fri Dec 9 2011 10:57:55 by ZANL188

Sponsor Message:
Printer friendly format