Human Space Travel

[crosscountry]

We're talking about life in space right?


how far away, timewise, is it until we can afford to send a man to Mars? What about radiation poisining? Do we have the technology to protect astronauts for that long?

[Ilya]

If there were a truly overriding, hang-the-cost reason to go to Mars (such as winning Cold War), then US, or US and Russia together, could do it in the matter of 4-5 years -- with significant risk to astronauts' life. In the absence of such a reason, I do not believe NASA or any other government agency will ever manage it. I expect first people(they may well be cyborgs by then) to reach Mars around 2100, and to do it privately.

As for radiation poisoning, all things are relative. Soviet and Russian sailors who volunteer to serve on nuclear submarines are advised to have children right away, becase within two years they are sterile. Cancer in the old age is almost a certainty for these sailors. Yet they go on serving anyway. Being an astronaut is at least as dangerous as being a submariner -- people concerned about elevated cancer risk probably do not apply in the first place.

[crosscountry]

In Cold War Russia, they weren't given the choice.


I think we can minimize the outside risks like radiation before we send people there. There will always be inherent risks of space travel.


I hope to see men on Mars in my lifetime, but I was born in 1981 and have a greater chance than most.

[Ilya]

In Cold War Russia, they weren't given the choice.

Actually, they were. Service carrying extreme responsibility, such as aboard missile subs, was volunteer only. That is, you were drafted into Navy, but had to ask to become a submariner -- and the competition was fierce.

There are always people willing to take risks, but not politicians willing to authorize risks. At least not during peacetime.

[eburacum45]

A mission to Mars would need a large reserve of potable water; enough to get there and back (perhaps a little could be extracted on the planet's surface, but on the first few missions this will probably be experimental rather than to supplement the supply.

Place the water around the outside of the crew compartment to protect against radiation- it should stop everything except some of the cosmic rays.

Later space adapted humans may be genetically modified to be resistant to various kinds of radiation, as well as modified for zero gee living (this would affect circulation, bone density, balance, dexterity and many other things).

[Ara Pacis]

This may be another good reason for a world government. It may develop the treaties, funds, and wherewithall to send people into space and to mars. I don't think Mars will be initially visited by private interests as it will be plenty dangerous for a long time with envisioned craft. A good reason to go would be to establish infrastructure for long term marsology (areology?). Governments are usually best at establishing long-term infrastructures that would cost a lot.

[Sticks]

Would a nuclear powered, giant electromagnet not solve the radiation issue?

It worked on that BBC programme a while back?

[suntrack2]

that's quite right crosscountry, radiation is one of the most important thing of which the effect which is falling, much severe and a very difficult to simplify the best space trip, this is one of the most hazardous thing in the space, the effects of the space radiation in other words more severe than the radiation on the earth ?

[crosscountry]

We all realize that space is more hazardous because of radiation.


IIRC water doesn't stop this kind of radiation. Also the astronauts can/do already recycle the water they need and only need enough to keep as a backup.

Lead works well. There are other possibilities that I can think of to block/capture the radiation. Let me post that on another forum.

[ranb]

Actually, water is an effective shield against all kinds of radiation. The most effective shield used on a nuclear powered submarine is the water or fuel oil in various tanks arranged around the reactor. Even though lead is ten times better than water for shielding against gamma radiation, water is much more effective against particle radiation like neutrons.

Ranb

[crosscountry]

is it neutrons that cause humans problems? I thought is was high energy EM waves

[antoniseb]

is it neutrons that cause humans problems? I thought is was high energy EM waves

There are many things that cause trouble for humans. Anything that can create ions inside our cells causes trouble. This can be gamma rays, or fast moving protons or electrons or neutrons. It can be muons, or relativistic heavy nuclei. It can be stuff cascading from one of the above hitting the shielding. We need to protect against pretty much everything except maybe low-energy alpha particles, and neutrinos.

[crosscountry]

I'm pretty good at blocking Alpha particles on my own

Neutrinos seem to ignore me.


those other particles spell trouble, but we can spell better

[Sticks]

Neutrinos seem to ignore me.

That's what they want you to think



But secretly they are plotting to take over the world

[crosscountry]

(sung to Ghostbuster's theme)


I ain't afraid of neutrinos

[Huevos Grandes]

We're talking about life in space right?


how far away, timewise, is it until we can afford to send a man to Mars? What about radiation poisining? Do we have the technology to protect astronauts for that long?

The short answer is YES.

+1 to what Ilya said. It could be done easily and completely in a few years, if cost were secondary consideration, and if human life was risked more heavily (think of the rocket failures and loss of life during the Mercury astronauts' reign).

Potable water and breathable are not big concerns, and the technology to recycle these resources exist today.

Also, radiation in space is not the gigantic problem it's made out to be either. lead-reinforced metals, such as titanium are used routinely on Earth to lessen the effects of radiation upon the human body. While a Mars-travelling vehicle would most likely have to be much more massive- and probably constructed in space, it is certainly doable. Early Mars travellers would simply have to risk sterility, perhaps.

[crosscountry]

(think of the rocket failures and loss of life during the Mercury astronauts' reign).

None of the Mercury astronauts died durning the Mercury program. Some died later however. Guss Grissom of course did, but that was Apollo.

Maybe you're refering to Russians?

[Huevos Grandes]

None of the Mercury astronauts died durning the Mercury program. Some died later however. Guss Grissom of course did, but that was Apollo.

Maybe you're refering to Russians?

Sure. Let me be more clear: "test pilots during the early Space Age".

[kzb]

Do we have any follow-up data on cancer rates in old astronauts? Are they detectably above average ? I would have thought this data exists by now.

Keith

[crosscountry]

Supposedly, the space flights of the first astronauts were too short to endure long term damage.


Especially the Mercury flights which never got above the Van Allen Belts.



I know the Apollo moon landers got bad sunburns from extended time on the surface.

[SSJPabs]

Hey, anyone know how they would create enough gravity-like resistance on the moon to have something sustainable for the long term? I mean, I know you can theoretically have rotating sections on ships to simulate some ammount of resistance so that a person's bones don't go soft, but on a planet's surface how would it work? Especially since there is already some gravity there to work with.

[crosscountry]

watch armageddon


they used air pressure on their shoulders to force the body down when walking

[Halcyon Dayz]

I mean, I know you can theoretically have rotating sections on ships to simulate some amount of resistance so that a person's bones don't go soft, but on a planet's surface how would it work?

You would use a centrifuge with a vertical axis, with walls that lean outward.
The result off the centrifugal force and local gravity together would
get you a force of 1 g perpendicular to the wall.

[crosscountry]

the "floor" would not be perpendicular to the ground but the sum of accelerations (gravity and rotation) would give one the feeling of 1g (with proper angular velocities and radius)


your feet wouldn't point down but rather "down and out"




edited for this:

similar to a tether ball.

[eltoddi]

To go off on a slight tangent from the station question:

If a spacecraft kept accelerating at 1g, wouldn't that create an artificial gravity field?

I know it is impossible with current propulsion systems, but say we manage to develop cold fusion in the next few decades it could run on water:

Build the spaceraft in orbit, configure it so that the crew compartment is surrounded by LARGE water tanks (takes care of at least some of the radiation), light the engine and just let it push you constantly. To slow down reverse the spacecraft and do the same. So you would have gravity for as long as you accelerated/decelerated (limited by the amount of fuel i.e. water you can carry).

Has the added benefit of getting to your destination quickly as you don't have to coast at constant speed, just start decellerating half-way.

Am I completely loopy or does any of this make sense?

They did a similar thing on a small probe with an ion drive if I remember correctly, it is very slow to start off with but just keeps accelerating.

[Kemal]

Yes, by accelerating at 1 g you would simulate gravity in the direction of thrust.

[crosscountry]

I like the gravity idea, but you have to realize the amount of force required to do that.


say your ship weighs 20,000 kg (very light indeed if we were to carry that much water)


then at 9.8m/sec^2 it would take almost 200,000 Newtons of force or about 60,000 lbs of thrust.

that's a lot of force. think if we actually added the mass of the extra water and scientific instruments. I can easily see it getting beyond even our conventional rockets capabilities.

and that is only for a few minutes. The trip to mars would require lots of time to be acclerating.