Slashdot Mirror
More on the Orbital Space Plane
AP has a decent piece looking at NASA's orbital space plane program, and describing it as a sedan compared to a tractor-trailer. National polls show that public support for the space program continues to be very strong.
and remote control is good.
"The space plane will have only two missions: to carry people up and down from the space station, and to act as a standby lifeboat, parked at the space station for the evacuation of astronauts if there is an emergency."
But what about when the shuttle repaired Hubble? will this kind of mission be no longer possible?
For those too lazy to read the article, this is only designed to be a commuter to the space station and back. It only would have a crew of 4, and would carry light cargo. It isn't meant as a do-everything satellite launcher/people mover like the current space shuttle. They plan on developing another vehicle to do the other chores of the space shuttle. Frankly, with the budget constraints NASA is under, I'm really surprised to read about them seriously developing more than one type of shuttle replacement, although I do think they are going in the right direction. We have several rockets designed to carry heavy payloads, I really don't see why they need to have the payload and crew all in one vehicle. What they should do is keep the rockets to lift the heavy payloads safely into space, then have the humans do what they need to do to the payload once it is in space (such as fine tuning, final preparation, and/or activation).
today is spelling optional day.
SpaceShip One has to be significantly cheaper than the 2.4 billion they're talking about for the simple ferry system NASA is talking about here. Couldn't they use some jacked version of SS1 (capable of reaching orbit) and save a lot of money/time/effort/etc?
***
What the space program really needs is a lofty goal and a challenge. We should aim for something like Mars, or semi permenant lab on the moon. We need someone to compete against. (I heard the private sector is starting to get interested in space so maybe in time?) We need a challenge like JFK's challenge to get to the moon. We need to find the drive to continue exploration. The tech gap to get to Mars is far less than it was to the moon. I just think motivation and $$$ are all that is really needed.
Of course, NASA will select the design with wings, probably the most expensive and error-prone variant, because it will be pushed through by the aerospace industry lobby.
We will observe this agency bypass any principle of common sense and experiences from successful space programs, just to have a new shiny and politically pleasing toy. It's like re-inventing the wheel - this time not a round, but a square shaped one.
What's so bad about winged designs?
- Wings are useless during launch and in space, they just add to weight penalty.
- Winged vehicles are unstable during re-entry and need a complex and error-prone automatic flight control system.
- Wings are less fault tolerant and more vulnerable to damage.
The worst idea is however to put a winged vehicle on top of a rocket! This concept has been repeatedly rejected due to very good reasons, the most important one being the high lateral and bending loads on the rocket!The good old ballistic capsule still holds all safety records in manned spaceflight - there are only very few lethal accidents, related to the large number of successful launches and returns. The Apollo capsule could land in an area of about 2 miles diameter so accuracy is not such a big concern. It could be further improved by using a parawing instead of parachutes.
The only real problem with ballistic capsules is the high re-entry deceleration due to the low drag and therefore the late beginning of aerobraking. However, no astronaut was ever killed due to re-entry or landing impact deceleration and the problem could be dealt with by using additional inflatable structures to increase drag during the early re-entry phases.
The reason is that that means that they would have to launch much more often to launch the same number of people. This means that for compared with the Space Shuttle that seated 7, the cost is almost halved; just from having to launch more.
In addition the planes would be cheaper in absolute terms because they are smaller. (It turns out that smaller rockets are about the same cost as big rockets per kg of payload- everything else being equal; which it seldom is at the moment; for example Pegasus is a small vehicle, but that's a solid vehicle with numerous stages, and it turns out to be very expensive, a liquid fuelled rocket with less stages would be cheaper if launched reasonably often).
This means, in turn that they would have to make proportionately more planes. That in turn gives economies of scale- each time you double the production run, the cost per item goes down by 15%.
It turns out that economies of scale are the most powerful known way to reduce costs- more powerful than reusability or using hydrogen fuel, or anything else.
Of course seating one person has it's problems- we probably don't have a rocket that small anymore, so you have to build a smaller rocket. There are also problems with the smaller size making it harder to fit a person in. But these are mainly difficulties not insoluble problems- pretty much it's much cheaper in the long run to seat one. That means that America might be able to capture space tourism market share from the Ruskies; at the moment the Shuttle is ridiculously more expensive for launching people into space.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"The Shuttle, and any next generation craft, is an attempt at creating not just a reusable vehicle, but also one which offers control at landing at a specific place; in this case a runway. Unlike a reentry capsule, which decends to some semi-random location by parachute, the Shuttle can glide toward a specific spot and land. This is a definite step up from previous capsuls in terms of technology and space readiness. And NASA wanted to do even better with their nextgen shuttle, the X-33 design goals were 'single stage to orbit', and would have allowed for a launch and land system without the costly solid fuel rockets. Also a reasonable design goal. Too bad the materials science for the hydrogen tanks isn't quite ready yet, nor are funds available to continue R&D.
NASA is failing because of two primary problems:
a) They lack funding from Congress, and as such are unable to both meet their launch goals and provide the necessary R&D for nextgen launch vehicles.
b) They have foolishly cut safety funding in order to meet those same launch goals, as demanded by Congress. They should have either said straight - we can't meet your goals with the funding alloted, or dumped the Shuttle program and moved to traditional rockets (as you stated in your previous post).
But to say that their R&D toward an orbital space plane was misplaced goes against the very grain of space exploration. At some point we're going to need vehicles that can operate in both space and the atmosphere. NASA obviously committed themselves toward the goal of creating such ships. Space will go nowhere if we only launch rockets into LEO and land in capsules by parachute. You can argue that our materials technology isn't ready yet for the challenges creating real land to space ships, but you can't argue that such a technology is the end goal for any space faring society.
This is JMO, coming from someone who isn't either an aerospace engineer or involved with NASA - and as such has simply a semi-informed opinion to offer.
Best,
Maynard
This initiative has been a long time coming. As it has already been pointed out by many posters, a smaller shuttle would have been seriously considered and perhaps even realized during the inception of the current shuttle if it hadn't been for political and bureaucratic wrangling (especially on behalf of the US defense force). I would like to be excited about this announcement, I really would. But I find the most proper reaction to be a simple yawn, as in "here we go again".
The fundamental ideas behind this announcement has been around for a really, really long time, and it was not an isolated development. The Europeans were putting serious effort into a program called "Hermes" with nearly the identical objectives for years before abandoning it 10 years ago. Similarly, Japan - with a space budget of a tenth that of NASA's - continues to pursue their own mini-shuttle dubbed "HOPE-X".
With these events in plain sight, one has to wonder why on earth it is so difficult to do the right thing. The ISS, despite being somewhat of a white elephant, is still a pretty decent lightning rod for stimulating international cooperation. Isn't it reasonable to assert that pooling resourced from all 3 nations who've already dreamed of mini-shuttles (US, Euro, Japan) in addition to anyone else who might want to participate (Russia, China, India) might actually get an astronaut-ferry built with decent price/performance/safty perameters? With the resources of international partners, we can reduce not just develope costs by leveraging the R&D others have already put into it, but also distribute the manufacturing responsibilities and perhaps even operational costs. Additionally, what can be learned from the work already put into the X-prize by various participants. Think of the possibilities if space faring for the forseable future is "standardized" on one vehicle by several nations which helps to build it. Economy of scale means production up, cost down, and in the end, science and exploration wins - everyone happy!
Stay sentient. Don't drink bad milk.
Combining humans and cargo in one vehicle is not such a good idea. Humans require extra safety margins, less G loads and abort options that cargo does not. All of those requirements add weight to the vehicle which in turn increases fuel loads and that then in turn increases strucutral requirements ... Also a lot of cargo is dangerous to humans, so when loaded on a manned craft more protections must be taken.
To build the best human->LEO transport system you want to keep it small/simple/safe and single purposed. I have reservations about even building a "plane" like vehicle. What does it do for you? When going up to orbit, it's dead weight, worse it's increased drag. On return it only gives you marginal cross range capabilities, and with the high landing speeds the number of landing sites are limited. Plus there is the problem of the landing gear compromising the integrity if the heat sheilding. Capsule design is simpler and most likely safer. Are there not *more* landing opportunities with a capsule anyway?
I suppose I am a bit radical in my thinking, but don't we already have a partner that has what we need? Why not just use the Russian vehicles. We could spend the money on something else, like getting going on building an international moon base. Using advanced robotics and tele-presence to get things going would seem to me to be a good approach. We sure could use the technology developed from that to help us here on Earth. What technological benefit will we get from building another space plane or capsule. We already know how to. Is it not time to pass that along to the private sector?
Also insn't there a world wide surplus of launch capacity now? Should we be thinking about using some of that to ferry supplies to the space station and beyond? If it were me I would be offloading things from STS as quickly as possible. Again the Russians have progress, should we not leverage that vehicle? If we truly want to be good partners we should learn to use one another's capabilities to the best advantage of all involved.
Seeing that kind of pissed me off. Way back in 1967 McDonnell Douglas had created a dirt cheap space taxi solution for up to 10 crew just by sticking an extension on a standard Gemini capsule. However, the focus on the Apollo missions and later the Space Shuttle pushed aside any non-glamorous low cost solutions such as this one. Now our government is planning to spend countless billions to build from scratch a new space system that will probably have less capability than what Big Gemini could have provided 35 years ago.
You've already got a system capable of delivering probably 60-65 tons or so to LEO right under your nose!
Take the exisiting SRB+Fuel tank combination that launches the shuttle and design a payload-sled based around the shuttles existing motors without the fancy cargo-bay, wings, avionics, cabin, life-support etc. Hey-presto you have a heavy unmanned launcher based around existing technology.
You may even get better than 65tons payload because you won't need the fancy 'throttled' ascents (no need to avoid aerodynamic loading on wings).
Now why didn't I think about that before?
Ripping an new rectum in the fabric of spacetime.