curious question from a newbie

[Guest ginger25]

We were having a discussion last night as to the determination of when and where the shuttle lands. Is it based on windows, and if the window is missed, the shuttle would skip on the atmosphere?

[BobbyJoeCool]

If the shuttle tries to come in too shallow, it will skip off of the atmosphere like a flat rock when thrown just right on a pond. If it comes in too steep, the atomospheric pressure will tear the shuttle to shreds and burn it to smitherines.

[jowrose]

so what exactly (or close to it) is the needed "window" to land the shuttle safely? what fraction of a degree?

[Pangloss]

The window of landing opportunity is actually determined long before the shuttle comes anywhere near the atmosphere. About an hour before, if I remember correctly. They make the decision based on various factors, with weather at the landing site being the biggest variable. The decision is made, then thrusters are fired in the direction of current travel, slowing the ship so that it drops into the atmosphere. 90 minutes later it's on the ground (whether the weather is still cooperating or not).

[jowrose]

but do you know how precise it needs to be so the landing is successful?

[Pangloss]

I sure don't, sorry about that, you're going to have to do some digging for that one. My guess would be that it's pretty important, which I imagine is why they let the computer fly virtually the entire program, with the pilot taking over just before it touches down (right about where the wheels pop out).

 

In aviation terms, it's easily the most challenging landing there is, blowing away the dangers of, say, a night-time carrier landing in a raging hurricane. It's not even so much the fact that you can't go around for another attempt, it's just the fact that the thing is barely flying at all, with a descent profile that almost boggles the mind. Moments before it touches down it's still descending at several thousand feet per second, a rate that would have even the most seasoned 747 passenger grabbing for the nearest air sickness bag.

 

One of the more mind-boggling moments is when they put the time-to-landing statistics on the screen. It'll say something like "2500 miles out" and "150,000 feet" followed by "15 minutes to landing". And at that point it's practically standing sill compared with what it was doing in orbit. (grin)

 

Any way you look at it, it's an amazing piece of work.

[Pangloss]

And, by the way, I predicted recently in another thread we will never see another one launched. I still believe that to be the case.

[jowrose]

you mean besides the shuttle launched a few weeks ago?

 

all the programming for the landing and approach programs has to be flawless... anything below perfection and there goes another few billion dollars, nevermind 9 lives and the end of the shuttle, perhaps even of American manned space flight. I recently read that for Discovery's last launch (was it Discovery? I think so, i hope i'm not wrong or i just made a fool of myself) they finally upgraded to flat-panel displays in the cockpit rather than the mechanical dials and cathode-ray tubes that have been around for some 20 odd years.

 

and to think that some poor soul forgot to convert meters to feet for that one mars landing probe... such a mistake could definitely happen again

[BobbyJoeCool]

The window, I believe I heard has to be within 1°. There is little to no margin for error.

[jowrose]

i though it had to be far below 1 degree. maybe a quarter of a degree. I'm not sure though, I just know it's gotta be incredibly precise.

[Pangloss]

I believe they have a max capacity of 7 on the shuttle, rather than 9. But yeah, I mean that due to the problems of this past mission, we will never see another launch. It's unfortunate, but I think that's the way it's going to go down.

[jowrose]

Ok, yeah you're right about the 7 crew. I thought it was more, don't know why...

 

Well what do you think about all the alternate spacecraft NASA is trying (and hiring others) to design?

[Pangloss]

Some of them are interesting. I think the question in general is a very interesting one. Unfortunately it's a bit early to get much of a feel for it at this point.

 

For one thing, it appears that we will lose the ability to return large payloads from orbit. But that ability was rarely used by the shuttle, because you pretty much had to dedicate the entire mission to that purpose. Much of the reasons why the shuttle was so ineffective at its original goal of reducing the cost of space travel is because we asked it to do too much. Perhaps getting back to older methods will give us a chance to subdivide tasks amongst different vehicles that can be optimized for efficiency.

[jowrose]

that's true. I read somewhere that the Russians were developing a larger spacecraft solely for the transport of materials into space (mainly to ISS i think). Perhaps NASA will develop a universal propulsion/rocketry system for launching a whole variety of smaller vehicles, carrying equipment supplies or astronauts.

[Pangloss]

I'd be interested in reading more about that if you happen across a link.

 

You can read more about NASA's current plans, and the current approaches being developed into proposals by two coalitions from the military-industrial complex, at this URL:

 

http://en.wikipedia.org/wiki/Crew_Exploration_Vehicle

 

It's worth noting that while Russia's manned program is more or less dead in the water without US taxpayer subsidies, China has not hesitated, and has announced that it will be launching its second manned space mission in just a few months. They're also taking aim at the moon and permanent space habitation.

[jowrose]

Wow that's a good link. Thanks.

 

China is taking aim at permanent space inhabitation? The kind Americans have been "planning" for about 2 decades? lol

[CPL.Luke]

china has money though, does anybody know how much money their putting in their space program?

[jowrose]

no, i have no idea. But their economy is growing like 9 percent a year. by 2020 they'll be second only to the U.S. unless something happens...

[Ophiolite]

china has money though, does anybody know how much money their putting in their space program?

According to this interesting article, which contrasts the Japanese and Chinese space programs, it is less than the US $2 billion committed by the Japanese.

http://www.guardian.co.uk/space/article/0,14493,1431062,00.html

[jowrose]

wow, it's another space race... again between commi and capitalist societies. and only, what 30 years after the U.S. and the U.S.S.R. ...

 

And whatever happened to Bush saying he wanted another man on the moon? He doesn't feel like it anymore? I understand that the space program (or at least the shuttle) is declining, but we can't stop exploring (or re-exploring) and finding more information.

[Pangloss]

The moon and mars are part of the developing program. Read the link on CEV I pasted in above.

[Ophiolite]

And whatever happened to Bush saying he wanted another man on the moon?

Remember that this is a long term plan, designed to put man back on the moon no earlier than 2015 and probably not to 2020, with a manned Mars mission no earlier than 2030.

So the plan is alive, but certainly not well. If you can find anything other than fatuous, fourth grade summaries and pretty pictures at the NASA site, please let us know. ["]http://www.nasa.gov/missions/solarsystem/explore_main.html]

[JustStuit]

btw the space shuttle we have now does not have the capability to go to the moon. the older ones we used did but the new ones are used for low earth orbit

 

http://www.nasa.gov/centers/kennedy/about/information/shuttle_faq.html#15

[Ophiolite]

btw the space shuttle we have now does not have the capability to go to the moon. the older ones we used did but the new ones are used for low earth orbit

There were no older space shuttles (unless you include Columbia and Challenger, destroyed in accidents, or the prototype Enterprise, which never flew.) No shuttle was ever capable of going to the moon.

[JustStuit]

what were the ones went to the moon called? i forgot. sorry for the mix up. was it the atlas rockets, were those manned? I cant remeber