The Next Generation of Human Spaceflight

[GIThruster]

What should it look like?

Options for consideration:

1) All flight to LEO is managed by private industry and the world's nations are the consumers--at least to start.

2) All nations interested in participation, each place $10 billion in an escrow account to be used for human spaceflight. This entitles them to a seat on the first interplanetary spacecraft(s).

3) Design a large spacecraft, able to take 8 crew to Titan, land the entire craft on the surface, support exploration for a minimum of 2 months, and return to LEO where it is refurbished and sent out on its next mission. These same spacecraft can fly missions to hundreds of different places of interest in our planetary system.

Just for fun, what would such a spacecraft look like?

[chrismb]

State the objective of this human spaceflight.

Why waste all those resources and brain power when people on the planet are still dying from dirty water? Why not pay attention to something worth while?

[kunkmiester]

Because greed and corruption will mitigate the affect of that money on the dirty water problem. It'll probably affect the space program referenced as well though. Pick you evil.

[GIThruster]

State the objective of this human spaceflight.

Why waste all those resources and brain power when people on the planet are still dying from dirty water? Why not pay attention to something worth while?

Sorry, you're off topic. If you don't believe that human spaceflight is its own reward, you don't belong in this thread.

[chrismb]

Sorry, you're off topic. If you don't believe that human spaceflight is its own reward, you don't belong in this thread.

That's the most arrogant and self-serving response I have ever seen on this board. Not the rudest, but definitely the most self-serving.

So just explain to me, then, how does "I've got an idea. . .how about Chris and i, and Aero and icarus and Kiteman and anyone else interested, all find something worthwhile to argue over? ... How about, if we're gonna burn the brain oil, we use it for something useful?" address the topic question of the thread in which you put that text?

My question is on-topic. What is the objective of human spaceflight? It is impossible to do a good job on anything if you don't know what the job is. You merely have to say 'to send a man into space, and return him safely to the earth'. That would be an objective, only, I would then suggest you spend more time on the things not done before - if it is to be an accomplishment for its own reward.

If you want to pay money to get into space just for the heck of it, then I would strongly suggest we do something useful along the way and start clean-up operations of all the orbital junk that now pollutes the Clarke belt.

[rjaypeters]

You want an objective for human space flight?

Try this:

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

Protection of our planet is my primary motivation for interest in space programs, hence my participation in the design portions of this forum. I would rather see a Bussard-powered heavy lift vehicle helping with NEO shepharding than a crash program to build a pulsed external plasma (the original project Orion) when astronomers detect a Large Object heading our way.

With apologies to Robert Heinlien, if you are in orbit you are half-speed to anywhere.

[chrismb]

I am fully on board with that issue. Thing is; why does that need to be manned? I would tend to think robotic craft orbiting the moon and on standby to intercept would be the preferred solution.

Manned missions only seem to make sense for exploration and resettlement. So that´s either a Martian base (if so, why) or interstellar (but no chance until we have a new propulsion system).

[rjaypeters]

Why crewed missions for Spaceguard? I'm thinking of three primary reasons:

1. Adaptability: Robotics and tele-robotics are not yet sufficiently adaptable to cope with situations we not have envisioned before we designed the equipment. Example: which variety of Large Object are we pushing?

Comet - a direct push against a central body is probably not going to work, so people on-site will need to observe and report the results of experiments.

A rock - a direct push would probably work, but care is needed for placement of the working platform to push against.

Something neither comet nor rock - see comments for a comet.

2. "There are things men must do to remain men."* I used to scoff at such romantic notions, but as I age and see _some_ signs of degeneration of society in the United States, I see the need of frontiers where people can struggle against Nature and not so much against each other.

3. Spaceguard missions will be, I hope, the least time-consuming use of Bussard-powered spacecraft. I believe people do not need to perform all space exploration, but we do need to be present for some of it.

Robotic craft will probably be adequate for heavy lift missions, but I expect Bussard-powered heavy lift vehicles to have enough performance margin to carry a small crew and be sufficiently versatile to justify a crew.

With solar system settlement missions, I agree the simplest method is to carry at least passengers and a crew would probably be useful also, if nothing else, to keep the passengers from getting the willies flying in a robot-piloted fusion-powered vehicle into deep space.**

About why a Martian base: Although I think a good Spaceguard program reduces the need for a solar system settlement program, I think it is useful for humanity to live places other than on the Earth (see my earlier comments about frontiers).

I'm not as much a fan of Mars bases as I am of manufactured space colonies with lots of interior volume, 1g centrifugal gravity and nice, thick walls to last a long time. A solar-powered (preferred) or Bussard-powered central light source would be pretty nice, too.

I'm pretty sure I don't want to condemn my children's children to live in a Bussard-powered generation ship heading toward Alpha Centauri, but I think they might like the options available in choosing where to orbit in this solar system.

But I have drifted very far-off topic.

To get to GIThruster's original question: Thanks for not requiring lift-off from the Earth's surface!

Bussards solve the power problem which solve the recycling problem (if you have enough power any chemical process can be reversed or bypassed). Even for a fusion-powered deep space exploration vehicle, I think 1g continuous acceleration might be wasteful. To keep the crew healthy, I strongly recommend a habitat centrifuge (probably a ring for convenience) big enough to the crew out of each other's hair. Also, a really good (roomy, well-shield) storm cellar for the inevitable solar storms.***


One problem with a ring habitat is it becomes unwieldy to maneuver through Titan's atmosphere unless we enclose the ring in a envelope at which point we might as well build it as a flying saucer which thrusts along the axis of symmetry. It is desirable to "skin" the saucer to protect the interior from rain, dust, etc.

On the other hand, if the Bussard provides enough power for continuous 1g (okay, at least 3/4g) acceleration, drop the habitat ring and build a scaled-up Delta Clipper - probably a little more squat because there might be some good winds on Titan (don't want to tip over!). This is another (pardon the pun) area where the saucer has an advantage.

*Apologies, but it's Star Trek quote.
** Is that a set-up for a sci-fi horror movie?
***There are interesting hints about eletrostatic and/or electromagnetic charged particle shields, but dumb mass is probably our best bet for now.

[93143]

It's not a question of power; it's a question of mass fraction. A Polywell doesn't put out nearly enough power for 1g all the way to Titan, not by several orders of magnitude. This is because as Isp increases, thrust decreases, so to get 1g with reasonably high deep-space Isp (say 300,000 s) you need a preposterous amount of power (approaching 20 TW for a 1000-tonne stack in LEO, which has to weigh only 100 tonnes including the power plant when it arrives at Saturn eight days later).

If you want 1g to anywhere in the solar system, you'd better hope the Mach effect is real...

[GIThruster]

My question is on-topic. What is the objective of human spaceflight?

No. Your question is not on topic. The topic presumes what you intend to question. I asked what the next generation of human spaceflight should look like. You want to question whether there should be one.

Start you own thread so we can all better ignore you.

[GIThruster]

It's not a question of power; it's a question of mass fraction. A Polywell doesn't put out nearly enough power for 1g all the way to Titan, not by several orders of magnitude. This is because as Isp increases, thrust decreases, so to get 1g with reasonably high deep-space Isp (say 300,000 s) you need a preposterous amount of power (approaching 20 TW for a 1000-tonne stack in LEO, which has to weigh only 100 tonnes including the power plant when it arrives at Saturn eight days later).

If you want 1g to anywhere in the solar system, you'd better hope the Mach effect is real...

I doubt the Poly will be in service to enable the next generation of spacecraft design. Lets remember, OBama put Constellation on hold so the entire program can be redesigned over the next five years. Poly won't be ready.

I think you did indeed identify the real challenge as I see it. If we're to have an affordable human spaceflight program, we have to stop throwing away spacecraft which means we can's stage to land on other planets. If therefore you can assemble and launch from LEO, but land the entire craft on a place like Titan, you have a spacecraft that you can use for decades. Actually, I think one wants a small fleet, just like with Shuttle, so that many nations can be involved and many missions flown. There's real savings with more than one spacecraft and you can fly rescue missions.

I think TRITON would enable this above. It's possible it would enable SSTO as well. I'd have to go back and look at the specs, but IIRC, when using the LOX injection, it has fantastic thrust to weight. You can't do this all the way to Titan, nor even Mars, nor even to the Moon, but you can do this for landing on planets with smaller gravity wells than Earth.

Probably, TRITON could enable spacecraft we don't have to throw away and can use for decades at a time and thirty years really should be enough for the "next generation". One has to hope M-E thrusters would be around much sooner than this.

[GIThruster]

For your consideration, here again is a paper on the TRITON thruster.

http://www.engineeringatboeing.com/data ... 4-3863.pdf

IIRC, TRITON would cost about $1 billion to develop (if it were not bungled by NASA but instead handled by P&W.) If I'm reading this correctly, such a thruster can be used for SSTO, for providing power to spacecraft, for providing high speed transit compared to chemical and for enabling missions like those mentioned above. Also, most of the systems that would need to be developed would work with the Poly, so would promote a next gen, follow-on fusion thruster.

I'm not sure that such a thruster would necessarily make SSTO cheaper than SpaceX launches, but it's certainly worth consideration.

[GIThruster]

About why a Martian base: Although I think a good Spaceguard program reduces the need for a solar system settlement program, I think it is useful for humanity to live places other than on the Earth (see my earlier comments about frontiers).

I'm not as much a fan of Mars bases as I am of manufactured space colonies with lots of interior volume, 1g centrifugal gravity and nice, thick walls to last a long time. A solar-powered (preferred) or Bussard-powered central light source would be pretty nice, too.

For next gen Human Spaceflight, I'm not a fan of bases of any sort. I think you make a good case for them, but my concern is that we can't pay for them. Personally, I'd like to see us work on a transport system and wait to see what private industry thinks they can do to make an economic case for its use. That's why I'm proposing pure exploration for next gen. Bases and colonies seem to me at least a generation after that.

To get to GIThruster's original question: Thanks for not requiring lift-off from the Earth's surface!

Yes well, I'm trying to simplify as much as possible and make things as cheap as possible. It may be that with a TRITON thruster or something close to that capability, we'd still want more than a single space vehicle and perhaps a SSTO launch vehicle. It'd probably be easy to make the case for a robotic refueler. With the same thrusters, you might for instance build a craft that does nothing more than deliver fuel to destinations. Lets take Titan again. If the mass fraction is just too low to put the entire vehicle on the Titan surface, perhaps you'd leave the main fuel tanks behind in orbit. Send a refueler out beforehand to leave fuel in orbit. Then you not only don't have to lift mostly empty tanks down to Titan and back up again, but once you get back from Titan's surface, you can refuel for the trip home.

Of course this adds huge complexity and you don't want to do this if you can build a craft that stays in a single piece, and can lower all that fuel to the surface, then reboost it. How inexpensive you can make the system therefore relates directly to the ability of the thrusters. Ideally, a single launch vehicle and a single exploration vehicle is the most economic and simple system, save for a vehicle that can fly from the Earth's surface to Titan and back, which it seems obvious to me the TRITON cannot manage.

[krenshala]

I am fully on board with that issue. Thing is; why does that need to be manned?

I have a very simple, and yet extremely important reason why having people in space is better than remotely operated drones -- light lag.

I don't care how impressive the engineering, hardware or software, people are the ones that make the decisions. If a probe detects something it has to ask for instructions or, at the least, inform its human masters that it saw something. Then people make a decisions: ignore it, investigate it, etc.

If you have people in space, you remove at least some of the delay involved in that.

As to your original objection (why spend on space when people on earth don't have water), it is my experience that the water problem on earth was solved ... the PEOPLE problem (a significant fraction of the population are just plain mean) is why so many people lack access to good water right now.

Oh, and didn't expenditures on past manned space missions lead to advances that made providing water in inhospitable places easier than ever before?

[GIThruster]

There are several water purification systems designed for space both by NASA and its SBIR partners, and by the Russians. Some of them are slated for commercial use in places like Africa since I believe 2007 if one wants to check.