paulw@amd.UUCP (Paul Woods) (01/28/86)
I have been wondering what they mean when they say that the Shuttle, or other space vehicle, has missed the launch window. Is there a region of space that they need to travel through in order to minimize the affects of the Van Allen belts or does this term refer to an on ground time table? Any help on solving this question would be appreciated. paulw
jss@ihu1e.UUCP (Smith) (01/28/86)
> I have been wondering what they mean when they say that the > Shuttle, or other space vehicle, has missed the launch window. > Is there a region of space that they need to travel through > in order to minimize the affects of the Van Allen belts or does > this term refer to an on ground time table? Any help on solving > this question would be appreciated. > paulw net.space as been covering this lately. -- J. S. Smith AT&T IW There are lots of opinions around this place, but these are mine and no one else's.
jbs@mit-eddie.UUCP (Jeff Siegal) (01/29/86)
In article <2170@amd.UUCP> paulw@amd.UUCP (Paul Woods) writes: > >I have been wondering what they mean when they say that the >Shuttle, or other space vehicle, has missed the launch window. >Is there a region of space that they need to travel through >in order to minimize the affects of the Van Allen belts or does >this term refer to an on ground time table? Any help on solving >this question would be appreciated. > >paulw I believe it refers to making sure the shuttle is at the right place at the right time for such things as satalite deployment and shuttle landing. Jeff Siegal - MIT EECS
steve@jplgodo.UUCP (Steve Schlaifer x3171 156/224) (01/29/86)
> > I have been wondering what they mean when they say that the > Shuttle, or other space vehicle, has missed the launch window. > Is there a region of space that they need to travel through > in order to minimize the affects of the Van Allen belts or does > this term refer to an on ground time table? Any help on solving > this question would be appreciated. > > paulw Launch windows are determined by the type of mission you are trying to fly. For example, if you are trying to send a spacecraft to Jupiter, there are a set of optimum dates to leave Earth. If you tried to leave at some other date, the launch vehicle you are using couldn't provide the energy it would take to get to Jupiter. Another example might be a spacecraft which is to go into an Earth orbit where it can see the Sun throughout the orbit. If you launch into a polar orbit around dawn, this is not too difficult to achieve. However, if you launch in the middle of the night, you will need to do something to the orbit after launch in order to rotate the orbit around to where the spacecraft can always see the sun--this something takes energy and a lot of it. The launch window then is the period of time in which it is easiest to accomplish whatever you are trying to do. Oftentimes, if you don't go at the easiest time, you just can't go at all because the available launch vehicles aren't strong enough or your spacecraft can't tolerate the forces that would be needed. Another type of constraint is what is happening at the launch site itself. At least in the early shuttle launches, they wanted to be able to watch the launch vehicle during the boost phase. This meant that the launches had to happen during the daylight hours. Hope this helps, ...smeagol\ Steve Schlaifer ......wlbr->!jplgodo!steve Advance Projects Group, Jet Propulsion Labs ....group3/ 4800 Oak Grove Drive, M/S 156/204 Pasadena, California, 91109 +1 818 354 3171
kort@hounx.UUCP (B.KORT) (02/03/86)
If the spacecraft itinerary includes any measurements in space (e.g. shots of Halley's Comet), or any activity that requires a certain sun angle, then the launch must take place within a narrow time window. Otherwise the activity would have to be rescheduled (which may be impractical) or the activity would have to take place with inadequate sun lighting conditions. --Barry Kort
doug@escher.UUCP (Douglas J Freyburger) (02/10/86)
>I have been wondering what they mean when they say that the >Shuttle, or other space vehicle, has missed the launch window. >Is there a region of space that they need to travel through >in order to minimize the affects of the Van Allen belts or does >this term refer to an on ground time table? Any help on solving >this question would be appreciated. > >paulw The rockets used now can only boost so much so fast. Launch window timing is a question of what the orbits of the planets are and where they are now and will be at the end of the flight. We are so short on payload that we have to use transfer orbit very close to Hohman (sp?) Transfer Orbits. These are the optimal elipse-to-elipse (circle-to-circle) orbits, but they require close timing. -- Doug Freyburger DOUG@JPL-VLSI, JPL Mail Stop 23 escher!doug, escher!teleop!doug Pasadena, CA 91109 etc. <Generic Disclaimer>