NASA proposes new propulsion to cut Mars voyage to 3 days
1–10 of 105 posts
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#2Jane, Stop this crazy thing! or in other words, how do you decelerate the spacecraft once you near Mars orbit. You'd need either a ton of conventional propulsion fuel , or a mars based laser there too. Worse is that you have a limited energy sources and no one to mine them. Solar might help, but it'd take a helluva alot of planning to install them via some automated system.
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#3So over-under on this being viable before fusion power? Nice idea, but we are years away from this being viable. If we visit Mars it will be with chemical rockets first? This may be viable for some sort of highway system when travel is more common.
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#4Jane, Stop this crazy thing! or in other words, how do you decelerate the spacecraft once you near Mars orbit. You'd need either a ton of conventional propulsion fuel , or a mars based laser there too. Worse is that you have a limited energy sources and no one to mine them. Solar might help, but it'd take a helluva alot of planning to install them via some automated system.
I had the same question. One thing that crossed my mind is that if speeds like these are possible, you could let the spaceship fly a gigantic loop and slow it down on the way back to earth. Same laser for acceleration and deceleration. (Things I've learned from the Martian #1.)
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#5Jane, Stop this crazy thing! or in other words, how do you decelerate the spacecraft once you near Mars orbit. You'd need either a ton of conventional propulsion fuel , or a mars based laser there too. Worse is that you have a limited energy sources and no one to mine them. Solar might help, but it'd take a helluva alot of planning to install them via some automated system.
Regarding slowing down upon arrival, could they enter a low orbit and skim the atmosphere of Mars to reduce velocity?
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#6Whenever I read a story about using sails for propulsion in space I'm reminded of the short story Sunjammer by Arthur C. Clarke
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#7Jane, Stop this crazy thing! or in other words, how do you decelerate the spacecraft once you near Mars orbit. You'd need either a ton of conventional propulsion fuel , or a mars based laser there too. Worse is that you have a limited energy sources and no one to mine them. Solar might help, but it'd take a helluva alot of planning to install them via some automated system.
[deleted]
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#8Jane, Stop this crazy thing! or in other words, how do you decelerate the spacecraft once you near Mars orbit. You'd need either a ton of conventional propulsion fuel , or a mars based laser there too. Worse is that you have a limited energy sources and no one to mine them. Solar might help, but it'd take a helluva alot of planning to install them via some automated system.
I assume that all fuel taken with you could be used to stop, though at those speeds it might not be a wash. So perhaps atmospheric braking?
Still I could see the value for sending problems out of the system without having to do the orbital boost tricks with gravity
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#9back-of-envelope:
conservation of momentum: 2(num photons)h/lambda = (100 kg)*(c/3), so 5.9×10^36 photons needed to propel a 100 kg object to 1/3 speed of light. 1.5×10^18 joules of energy, which is 11% of the energy output of the US in 2001 (according to wolfram alpha). That's a 5.8 Tera Watt laser running for 3 days straight.
I haven't even gotten into dispersion of a laser beam.
The ludicrousness of this proposal is left as an exercise to the reader.
Edit: here's their proposal with physics. Just to be clear, I don't doubt the theoretical possibility, I doubt the economic and experimental reality. http://www.deepspace.ucsb.edu/wp-content/uploads/2015/04/A-R...
Re: NASA proposes new propulsion to cut Mars voyage to 3 days
#10I think the "Mars in 3" days comment is just for scale, not a serious proposal.
This is more about getting probes to whiz past other solar systems. As obviously, you can't stop the craft.