NASA's Constellatiion Program, cancellation (or not)

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They've also used nuclear propulsion for some of unmanned probes. In principle, nuclear propulsion could get a spacecraft to Mars in 2 weeks but apparently there are some safety concerns in putting on a manned spacecraft.

And said safety problems cannot be overcome unless we actually build them in free space, because the Moon Treaty forbids large-scale nuclear devices (with "devices" remaining pretty vague) in orbit or on the Moon, while one of the strategic-arms treaties forbids the construction of the NERVA nuclear rocket. (We won't even get into Orion here - couldn't use an Orion ship to launch from Earth anyway, what with the associated environmental damage from a series of massive nuclear explosions...)

The only problem with using an ion thruster is the low delta-v - people are still enamored of watching Our Brave Astronauts disappearing in a blaze of rocket exhaust. It would take days for an ion engine to get a manned craft up to any kind of speed - of course, it keeps accelerating the whole way, so if you can develop 0.001g, it would take about 14 weeks to get to Mars orbit on a Hohmann trajectory (rotate at midpoint to decelerate the rest of the way, of course).

Which missions? Please provide some references.

ruveyn

Do you mean ion drives?

*shrug*

Suit yourself, I never said anything about perpetual motion. The truth is far from it. As for physical laws, more or less I was referring to how all the vectors need to add up. The typical complaint is that everything cancels out so it can't happen. Why focus on the obvious?

Some of our earlier long distance probes used nuclear powers sources for the electrical systems, since the vessel would be so far from the sun the photovoltaic converters of the time could not power the systems aboard the space craft.

No U.S. heavy long distance probe used nuclear propulsion systems.

The ion drive used to visit a comet (or was it an asteroid) is not a practical propulsion system for manned missions. Not enough energy is generated.

ruveyn

The problem is that they have to cancel out to satisfy Newtons Third Law of motion. The device you are referring to only moves because it uses the surface it rests on as the reaction mass and relies on friction. See the following:

http://gltrs.grc.nasa.gov/reports/2006/TM-2006-214390.pdf

I was mistaken. I was thinking about proposed nuclear propulsion systems and not ones that exist already.

1. The method to which I am referring does not violate Newton's Laws.

2. The surface is irrelevant, in fact it gets in the way.

3. Nice PDF for general information, it includes the simple parallel pendulum test to help address point 2. Also not applicable.

4. Especially helpful to clarifying understanding is the very brief section of similar concepts not in this category.

5. As I said, why focus on the obvious? The document is a reference not for what works, but for what does not work.

The only useful thing I can think of for the manned program is the repair jobs on the Hubble which is the product of the un-manned program. Our excursions to the Moon, so far, have produced a trash pile on the lunar surface and some foot prints that will last a few billion years.

ruveyn

Aye Matey, we be needing Clipper ships with Solar sail, the wind always blows in space.
From Earth orbit to the Moon is a short cruise, and large cargo can be brought if not fast, at least cheap.

Getting it into Earth orbit will cost, $40,000 a pound, but the long haul will be cheap, and a major telescope on the dark side would be useful. We could use several, something wide angle to look for planet killers, the current telescopes are narrow vision, and there is a lot of space.

The Hubble was scaled to fit the shuttle, the simple way to build a moon base is build one large enough to have living quarters within, something skyscraper size. In low gravity light constructions work, no storms, earthquakes.

Like the garbage and footprints, it should last a billion years.

A solar array on the bright side could power it, as it is a bit cold on the dark side.

It would have a spinoff of building the method to get enough up there to build a real space ship.

We do not have the engines, but the living quarters, we know what humans need, and we must produce food and fuel before we can think of long trips. It would have to be large enough to support a breeding population as it will be generations to the next star.

People living in space will mutate quickly, within a few years they could not return to Earth, so how they are to survive the gravity of another planet generations later is unknown.

I can see them adapting to space, but not supplying their own materials, and being unable to mine much from the void. As I recall Hydrogen is a metal, if we could figure out how to get it in solid form it would be great, it is everywhere.

Space born, raised in zero G, would be very different.

Six months on the Moon, as an adult, you could return to Earth.

It is within our ability and would cost about as much as a war.

Newton's third law is none other than the conservation of momentum. No one has canceled that and no one is going to, at least not the the foreseeable future.

ruveyn

Ok I'm curious, just what system are you referring to?

Again, the moon rocks that were brought back from the Apollo missions have provided some insight into the geology on the moon. The also confirm a theory that the moon was formed from giant impact event of the Earth with another body. The Russians only brought back a small amount of material with their unmanned sample return missions compared to Apollo. You can't really expect the manned program to accomplish much if all that is done is to fly into Low Earth Orbit. As you've also said in a previous post, the far side of the moon is a perfect place to build a large radio telescope. That can't really be done without having a base on the moon.




You've missed the whole conversation I've been having with the guy with that flying pig avatar. I think he wants to make a reactionless drive and I'm saying it's not possible. Go back and read it.

Reviving old thread.

It appears that we could have an update. There seem to be recent news reports that the Constellation Program may in fact be canceled. Although an increase in funding does seem to have been granted to NASA for their COTS program. The fact that the administration would want to support the running of the International Space Station to 2020 was evident from the beginning when I started this thread. But at least the launch of the prototype Ares 1-X has taken place. As I've said before, I think human space exploration does have its place. But what will the future of that be now? The Constellation Program page on NASA's website is still up and running. Has NASA made a statement about this yet? Also, since congress seemed to of supported the Constellation Program when the Augustine Commission presented their finding, won't there be some opposition to such a cancellation? I also notice that, earlier in this thread, some people have made posts of space travel in general. So thought it would be appropriate to revive this thread because iamnoparakeet has also started a thread about interest in space travel in the PPR forum.

I just heard from someone from Nasa on short wave and
the Constellation program is going to be maybe sluggish
but NOT canceled. (I hope that's true).

It is very sad how SLOW rocket science is these days.
When there was a lot of doubt about a person landing
on another world, they hurried up and got on the moon,
and they didn't have technology in 1969 that we all have
now. It is a shame that NASA plans to buy rockets from
Russia after they stop using the space shuttle. Some
rocket scientists think we should skip the moon and go
to Mars. They designed the whole mission to be cheaper
than NASA's plan, but NASA doesn't like it because they
want lots of stuff up there first, the space station, the
space elevator, the moon base ... but if they are not
going to have their own space ships for a while they
should plan more efficiently with what they do have.
1969 is like in the middle of the 1900's. How many
of you... OK, imagine you were a kid and everyone
was talking about moon landings and all of the sci-fi
like Star Trek was all about going in spaceships to other
planets... but then you grow up and the moon hasn't
been gone to all your life. It's like Pyramids. People all
over the world used to make them so long ago that
nobody really knows why anymore, nor how they did it!


Microsoft wastes tons of money doing nothing, or the
same buggy solitaire virus over and over. Windows was
invented by Xerox before anyone went to the moon.
They should have made a moon base instead. VISTA
was the biggest failure of all time. (Or so they say, so
if Chernobyl is number 2, Vista must really be bad!)
They COULD have gone to the moon instead. Who
wouldn't trade Vista for another man on the moon?