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CaptainPanic
Post  Post subject: What would you do with a Space Shuttle?  |  Posted: Tue Aug 09, 2011 1:54 pm
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The case: you get a Space Shuttle
Assume for a moment that NASA would give you a Space Shuttle, and that they would give you the launch pad too.
For the sake of the discussion, let's also assume you have some serious money to burn... enough to get it to go up one last time. What would you do?

My plan: get it to Mars
(Don't worry, I end this post by asking what would you do? If you don't like reading, just ignore this, and write what you'd do).
I think the Space Shuttle is quite suited for trips further away from earth. Maybe to Mars. I think it's expensive as a "Shuttle", but not as a "Space Craft".

Cargo
It can carry astronauts. Has life support systems. It has a cargo bay which could hold a lander. And it even has connections for external tanks and even (if you'd like) a Boeing 747... so while a boeing 747 is not so practical on a trip to Mars (maybe for living quarters? - I'm joking), it really shows that under its belly a Space Shuttle can carry stuff too, like the MOAFT (Mother of all Fuel Tanks). So, tick the box: huge cargo is no problem.

Meet the cargo in orbit
Obviously, you cannot carry all you need for a long trip to Mars in a single launch. Enter the Space Shuttle.
There is experience meeting objects in orbit (satellites or the ISS), and with docking. So, I think in-orbit refueling doesn't require much research... Finding the fuel tank in orbit is no different than meeting with the ISS, and the connection between fuel tank and Space Shuttle can most likely be re-used too. In other words, it's just a matter of doing.

Living space
Take a module of the ISS. Dock with it. And bring it along. (Or launch a new one, if the guys living in the ISS get upset when you nick their gear). We can copy it. We know it works, and we know it works with the Space Shuttle.

Mars lander
This is a bit of an issue. As far as I know, there is no Mars lander that we can easily use. However, we just established that the Space Shuttle has few limitations of how much it can carry. And we've built landers before. Now we just build a big one, which carries fuel to safely land a small research station (ok, just a decently equipped lander), and also a return pod. If it could be done on the moon in the 70's, while even carrying a buggy, then how difficult can this be in 2011 on a planet a lot further away with a much higher gravity?

Stuff you don't need
Like wings. Who needs wings in space? The Space Shuttle does. Because it's too much effort to take them off. We know how the thing works with wings. So, we leave them on. Besides, it looks cool.
Or a landing gear. We can do a cost evaluation what's cheaper: a Soyuz to get us back to the surface, or a full check of the heat shields and the landing gear before attempting to enter the atmosphere. Ok, we leave the landing gear at home. And the heat shields too for that matter.

Go, no go
And with that, it has simply become an issue of 'how much stuff do you need'? The Mars lander requires research and design. But the Space Craft to get to Mars and back, its fuel tanks, its living space, and all flight controls, boosters... it's all there. Existing technology. Existing designs even.

Costs
Using a Russian Proton rocket, you can get 1 kg in Low Earth Orbit for about $ 2000 (scroll down to the tables).
Assuming we need 2000 ton of fuel (that's about 3 fully loaded external fuel tanks of the Space Shuttle), we are facing a price tag of just 4 billion dollar in launch costs for all the extra stuff. And an additional 300 million for a shuttle launch.

Going home
Assuming our MOAFT carries enough fuel to get us back to Earth, we undock with our living quarters, and just dock with the ISS. We're heroes now, so I guess someone will ferry us back to the surface. Any Soyuz capsule can do it. After all, we've left the landing gear at home.

My point
I've just proven (without doing any calculations at all, so you know it's right!), you can get to Mars for 5 billion dollar, plus a bit of research for a Mars lander. A bargain.

You?
What would you do with a Space Shuttle? Park it in a museum, like NASA?

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Ophiolite
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Fri Aug 12, 2011 7:10 am
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We require a delta V of 6.1km/sec to move a spacecraft from Low Earth Orbit to Low Mars Orbit. The shuttle main engines have a specific impulse (ISP) of 465 seconds. This equates to an exhaust velocity of around 4.5 km/sec. The ratio of delta V to exhaust velocity is thus a little over 1.36. That requires that over 70% of the mass of the craft departing LEO be fuel. And that simply gets us to LMO.

Put it another way. To get from LMO back to LEO requires the same delta V. So the shuttle, its crew, the living habitat you want to put in the cargo bay and whatever specimens you want to bring back from Mars, all together must constitute less than 30% of the mass that arrives in LMO. The spacecraft plus payload mass leaving LEO is then less than 9% of total mass. And at this point you still haven’t even provided the mass for the fuel tank, or explained how you are going to keep many tons of propellant and oxidant liquid during a couple of years in space, or allowed for any safety factors whatsoever.

I’ll do more detailed calculations if you wish, but the executive summary is as presented at the outset. It won’t work. And I’ll add a caveat. Even if it did work the cost would far exceed the $5 billion you suggest. Even certified dreamer Zubrin uses a figure ten times that.

As to what I’d do with one last shuttle flight: take the planet’s senior economists and bankers. Load them into the shuttle bay. Once in orbit open the shuttle bay doors. Later, as they burn up in the atmosphere it would be the first time any of them had brightened up our day. 


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CaptainPanic
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Fri Aug 12, 2011 8:19 am
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Let me start off by saying that I realize I am probably simplifying things too much. Let's see how much though.

Weight vs. fuel

Space Shuttle Empty Weight: 172,000 lb (78018 kg) with SSME (main engines) installed
External tank Empty Weight: 58,500 lb (26,500 kg)
Zvezda (ISS) living quarters: 19,051 kilograms (42,000 lb)
Apollo lunar lander (complete): 32,399 lb (14,696 kg)

Using 1 shuttle, 3 tanks, 1 living quarters and 2x the lander weight, we have a total of
78018 + 3*26,500 + 19,051 + 2*32,399 = 241,367 kg.

And the 3 tanks will hold a total of about 2,200,000 kg of fuel. The ratio of empty weight to fuel in LEO is 9.1 : 1.

So, counting backwards from Mars departure, and assuming we bring back even empty tanks: In LMO (Low Mars Orbit) we have 241,367 kg of stuff, plus some more samples and a ton of food / drinks. Let's say 250,000 kg of stuff to bring back, which is 30% of the weight. Add the fuel, and we have 833,333 kg in total. And that means that we should have a total of 2,777,777 kg in LEO.

I am not too far off actually.

Other stuff
Regarding all your other remarks: I admit, there's no extra safety features, because I think it's gone over the top. Safety can make the price go up tenfold... testing, testing again, having 50 committees that evaluate and evaluate the evaluations... It's better to just have more spacecraft.

I wonder if you could cool the fuel (LH2 must be −252.8 °C) using passive radiators and reflectors. In the darkness, space can be quite cold.

Love your last remark! Douglas Adams is a genius (I assume you got the idea from him).

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DrRocket
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Mon Aug 15, 2011 1:21 am
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Ophiolite wrote:
We require a delta V of 6.1km/sec to move a spacecraft from Low Earth Orbit to Low Mars Orbit. The shuttle main engines have a specific impulse (ISP) of 465 seconds. This equates to an exhaust velocity of around 4.5 km/sec. The ratio of delta V to exhaust velocity is thus a little over 1.36. That requires that over 70% of the mass of the craft departing LEO be fuel. And that simply gets us to LMO.



The shuttle was designed for LEO. Even going to the space station was a stretch and required modifications and some careful payload manifesting to limit weights.

To get a mass fraction of 70% from Leo almost requires you to boost a loaded external tank into Leo. That is well outside the available lift cabability.

A Mars mission may be limited by the tolerance of the human body to long term exposure to zero g. The orbiter does nothing to address that.

A Mars mission is out of the question.

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spuriousmonkey
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Mon Aug 15, 2011 7:30 am
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I would dump it in the deepest abyss since it has killed any chance of a decent space mission due to its excessive costs, and capabilities. It's not something that should be celebrated.

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15uliane
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Mon Aug 15, 2011 2:54 pm
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DrRocket wrote:
A Mars mission is out of the question.

For the orbiter or in general?


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Nikelodeon
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Wed Aug 17, 2011 6:08 pm
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Quote:
What would you do with a Space Shuttle?

Crash it into the moon on autopilot.


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15uliane
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Thu Aug 18, 2011 1:07 pm
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Why?


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Nikelodeon
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Thu Aug 18, 2011 4:58 pm
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To get rid of it, once and for all.


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iNow
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Thu Aug 18, 2011 5:56 pm
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Nikelodeon wrote:
To get rid of it, once and for all.

The moon, or the shuttle?

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DrRocket
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Sun Aug 21, 2011 4:28 am
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15uliane wrote:
DrRocket wrote:
A Mars mission is out of the question.

For the orbiter or in general?


For the orbiter.

But at this time we do not have the necessary technology for a manned mission to Mars. There are developable concepts, but there is a lot of work to be done.

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x(x-y)
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Tue Aug 23, 2011 12:25 am
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DrRocket wrote:
15uliane wrote:
DrRocket wrote:
A Mars mission is out of the question.

For the orbiter or in general?


For the orbiter.

But at this time we do not have the necessary technology for a manned mission to Mars. There are developable concepts, but there is a lot of work to be done.


From what I've heard, the best way to achieve such a huge mission would be to establish a permanent Lunar base- given current economic circumstances, this will not happen for a long time unfortunately.

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drowsy turtle
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Tue Aug 23, 2011 1:27 am
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x(x-y) wrote:
From what I've heard, the best way to achieve such a huge mission would be to establish a permanent Lunar base- given current economic circumstances, this will not happen for a long time unfortunately.


With an escape velocity of 20km/h and a position in orbit around Mars, a permanant base on Deimos might be more useful. One could return to Earth simply by taking a running jump, and then waiting patiently.

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Ophiolite
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Tue Aug 23, 2011 2:04 pm
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drowsy turtle wrote:
One could return to Earth simply by taking a running jump, and then waiting patiently.

It might be more a case of wasting, patently.


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15uliane
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Tue Aug 23, 2011 2:45 pm
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x(x-y) wrote:
From what I've heard, the best way to achieve such a huge mission would be to establish a permanent Lunar base- given current economic circumstances, this will not happen for a long time unfortunately.

I think thats what the governmental space agencies are planning, but I think it is more expensive than just going straight there.

Edit: Not straight there, I think you would need multiple flights to get there with enough fuel for the return trip.


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CaptainPanic
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Wed Sep 14, 2011 3:15 pm
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DrRocket wrote:
15uliane wrote:
DrRocket wrote:
A Mars mission is out of the question.

For the orbiter or in general?


For the orbiter.

But at this time we do not have the necessary technology for a manned mission to Mars. There are developable concepts, but there is a lot of work to be done.

Care to elaborate a little? You seem to dismiss my plan, but you seem to misunderstand it as well.

I never suggested we bring a fully loaded external tank in one go. It goes up empty, and then gets filled. If you look in the 3rd post of this thread, you may notice that the empty weight of an external tank is only about 1/3rd of an empty space shuttle, which means you can sure as hell get it into LEO if you want.

And in the 1st post, I suggested that we bring up all the fuel and cargo in bits at a time, and fill up not one, but multiple fuel tanks in orbit.

The fun of this thread is not to just say that everything is impossible, and then dream about space stations... it's to see how far we could possibly get with existing technology. Sorry if this sounds a bit like flaming, but I want to get this back on topic.

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DrRocket
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Wed Sep 14, 2011 4:18 pm
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CaptainPanic wrote:
I never suggested we bring a fully loaded external tank in one go. It goes up empty, and then gets filled. If you look in the 3rd post of this thread, you may notice that the empty weight of an external tank is only about 1/3rd of an empty space shuttle, which means you can sure as hell get it into LEO if you want.



The orbiter has engines and avionics. The external tank has neither.

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CaptainPanic
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Thu Sep 15, 2011 8:31 am
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DrRocket wrote:
CaptainPanic wrote:
I never suggested we bring a fully loaded external tank in one go. It goes up empty, and then gets filled. If you look in the 3rd post of this thread, you may notice that the empty weight of an external tank is only about 1/3rd of an empty space shuttle, which means you can sure as hell get it into LEO if you want.



The orbiter has engines and avionics. The external tank has neither.

I totally agree. Most cargo has no engines.

Still, I fail to see why it wouldn't be possible to put that thing into orbit if we wanted to. Its weight is no issue. The size might be a small problem, but the Space Shuttle's maximum cargo payload (25,060 kg) is round about the weight of an empty tank (26,535 kg). And since the space shuttle seems well capable of flying and accelerating with the tank attached, it seems just a matter of not detaching it to get it to LEO.

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padren
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Fri Sep 30, 2011 10:09 pm

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Well Mars would be quite the use for an Orbiter, if it was up to me I would have used them to augment the ISS and brought the last crew home the Russian way. It would hardly be more expensive if you timed the crew's return a member at a time to coincide with other supply missions.


Once in orbit, it could be used as a secondary habitat, lab, and most importantly a fully redundant life-support system. If it could be maintained well enough it could even be a viable escape system - or at least provide a better-than-nothing place to retreat to in the event of catastrophic damage/fire etc.

Additionally, it could be positioned a few hundred meters "in front" of the ISS with the bottom of the bird facing forward so the body and wings could provide protection from micro-collisions. Most collision hazards (if I recall correctly) are immediately in front of the ISS along it's orbital path.



(That, or I would use it commercially to provide the XTREME Gambling Experience that you just can't get in international waters)


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kojax
Post  Post subject: Re: What would you do with a Space Shuttle?  |  Posted: Wed Oct 12, 2011 1:22 pm
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Alright, so let us suppose you start by doing a bunch of LEO trips from the surface of the Earth to bring up some additional fuel tanks and put them together in a bundle, or store them in a space station, ... or something so they're waiting in orbit. Also, you bring up a bunch of really strong cables.

Then, in space, you divide up the fuel tanks so that some are attached directly to your space shuttle, and some are clumped together in a big ball at the end of a long cable that tethers them to your space shuttle, making sure that the clump at the end of the tether has the same mass as your space shuttle (and the tanks directly attached to it).

Then, accelerate the space shuttle in order to start it and the clump of fuel tanks spinning around each other like the ends of a bolo. Now you've got artificial gravity. The next step is figuring out how to accelerate towards Mars while maintaining that same rate of spin. Probably a good idea to invest in some really advanced navigation software, and maybe hire some physicists to help walk you through using it.

Once you reach Mars, you will have consumed quite a lot of fuel, so it would be a good idea to shift the mass around a bit before heading back.


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