The long term space travel problem

[Safir]

I was thinking, the biggest problem about going to distant places is the bone & muscle loss issue. With new propulsion system breakthroughs would it be possible to make a spacecraft which accelerates at one G through half the journey and then turns around to decelerate at one G again? Lets say going to Mars for example. That would mean the crew spends most of their mission time on Earth gravity - no zero g health problems and a very quick journey too. Quick journey also means lower risk of solar flares!

I'm sure most people have thought about it. Guess the the costs would be too high, newer propulsion methods would be required, etc. Any comments?

 

[kelvinzero]

If you could accelerate at 1g, you could get around this solar system so quickly that you would never need to worry about the bone loss anyway, even if you were not standing in a 1g environment.

The 1g interplanetary/interstellar craft is pretty much the ultimate daydream of the hard sf space enthusiast but it is a long way away from being realized.

The bone loss problem just isnt that big. There are simpler ways around it. one of the most obvious is to simply spin your craft on the end of a tether to fake gravity with 'centrifugal force', but we will probably invent much less extravagant ways to prevent bone loss, such as exercise, a suit that keeps your bones compressed or applies a series of impacts emulating footsteps, or perhaps as convenient as a pill.

These solutions might be needed anyway once you get to the destinations which within this system are all much lower gravity than earth (except for venus, gas giants and the sun )

My own take on the problem is that it is only a very near term one. Once people really start living in space they will simply never want to stand in 1g gravity again. Even if they had an urge to return to earth, they would return to the 75% of the surface which is water, where the environment is practically weightless anyway.

 

[bdewoody]

It's all in the amount of fuel you can carry as you would need to burn as much to slow down as you do accelerating.

 

[Astro_Robert]

If bone loss is the primary concern, then a full 1G acceleration is not needed for most missions. I don't believe we know enough to evaluate long term bone loss versus gravity/accleration' but as most missions are modest in length, even a fraction of a standard 1G would alleviate a lot of the risk.

Today astronauts use a variety of equipment to help maintain some minimal stress of the skeletal system to maintain bone density, and this is reasonably effective. You can look up the 'COLBERT' which was the consolation prize for the commediate after he successfully hijacked the NASA voting in an attempt to get the Trinity node named after himself. This COLBERT devise is basically a treadmill with bungee cords to hold the astronauts down. Yes, astronauts still lose bone mass, but equipment like this helps to reduce the loss of bone and muscle.

 

[Safir]

Yeah I guess even having a quarter of a G would help. Do the astronauts take any special supplements or drug for reducing loss?

Something about the centrifugal force spinning solution troubles me. Wouldn't the spacecraft and the support structure/chassis or whatever have to take extreme stresses?

Yes I know about the COLBERT. Big fan of that show but I still voted for Serenity.

 

[vulture4]

Resistance exercise is really quite effective as a countermeasure for bone and muscle loss. Equilibrium for bone is reached in about 18 months, and people have actually been in space for over a year. The big problem throughout most of the space program was that the exercise equipment was designed by doctors and engineers, not athletic trainers. The treadmill is mainly for cardiovascular conditioning, as on earth. I doubt you could raise children without gravity, because there is no way to teach them to walk or develop basic reflexes, both of which occur before they are old enough to train voluntarily. But for adults it isn't necessary.

 

[JonClarke]

I was thinking, the biggest problem about going to distant places is the bone & muscle loss issue. With new propulsion system breakthroughs would it be possible to make a spacecraft which accelerates at one G through half the journey and then turns around to decelerate at one G again? Lets say going to Mars for example. That would mean the crew spends most of their mission time on Earth gravity - no zero g health problems and a very quick journey too. Quick journey also means lower risk of solar flares!

I'm sure most people have thought about it. Guess the the costs would be too high, newer propulsion methods would be required, etc. Any comments?

Looks like you are still new here so welcome. Love your avatar image too!

These are issues, but so far they are managable issues, as others have pointed out. For a Mars mission what proportion would be spent in zero G would depend on the mission profile. A Conjunction mission would require 6 months there, 6 months back, with a 18 montyh surface stay. No too different to a rotation to the ISS. An opposition mision would take about 8 months one way and 14 months the other, with perhaps two months on the surface. This would be more challenging for a microgravity and radiation perspective.

 

[SteveCNC]

You could build a balanced rotating section to the ship for a section of artificial gravity easy enough , using a dynamic balancing system to adapt to changes in mass along the rotating area . You could even make it like a dougnut with the largest diameter being the floor . Access to the other parts of the ship would probably not happen without stopping it since having a rotating seal in space is not a good plan IMO . But you could overcome the gravity problem fairly easy but a ship of that sort would have to be assembled in space and the way we do things LOL how long did ISS take ? and it's no where near as big as what would work well . Best bet possibly would be if manufacturing can be set up on the moon , I'll go be a machinest on the moon for a while .

One thing I see people forgetting when it comes to going to mars , it's not as simple as point it that way and go . There are launch windows each year and I am not sure if it would even be possible or practical to return after only 3 months stay except at very specific times and those windows are probably quite a few years appart .

 

[MeteorWayne]

I was thinking, the biggest problem about going to distant places is the bone & muscle loss issue.

ROFL, that's only one of dozens of problems, and it probably isn't the biggest. What about radiation, water, oxygen, food, etc,etc,etc...

 

[halman]

In the film "2001: A Space Odyssey," the solution to this problem is demonstrated. A centrifuge will create adequate acceleration to prevent bone and muscle loss, while avoiding people having to spend time exercising instead of working. Of course, some exercise is essential, and it will be far more effective if done in a acceleration field. But spending the majority of the time in an acceleration field negates the need to exercise just to avoid atrophy.

I am very curious as to what the effect of sleeping in an acceleration field would be. For a space station, spin may be impossible, or impractical, so how about a centrifuge with bunks in it? If you can combine weight conditioning with sleep, you again can avoid having to spend time doing nothing but exercising.

An aspect of the discussion which I have wondered about is the additional difficulty of astrogation when under steady acceleration. Every journey involves an orbit, and acceleration changes orbits, so doesn't steady acceleration require constant re-calculation of direction of thrust?

 

[Booban]

Why would it be so different for a space station or space ship halman? Besides what you yourself pointed out that it has to be adjusted for spaceships moving about.

The thing I don't like about generating artificial gravity in this way is that I don't trust engineers, manufacturers and moving parts, yeah, I know what an evil thing to say around here.

That thing, at least the first few iterations is going to hick up, screech, brake down, make a lot noise, vibrate, suddenly spin really fast, jerk, reverse spin, and everybody is going to be so insanely sick. It has be to 100% absolutely perfect, the slightest annoying noise or glitch will drive people so crazy they'll kill each other in their sleep.

 

[js117]

Here is a article on http://www.spacedaily.com/ about a study done on bone loss.
NASA studies bone density loss because it is one of the main effects of exposure to the weightlessness of space.

NASA Studies Find Omega-3 May Help Reduce Bone Loss.

http://www.space-travel.com/reports/NAS ... s_999.html

 

[tampaDreamer]

The issue is and will continue to be propulsion..