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Launch a Water-Propelled Satellite into Deep Space

kickstarter.com

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Re: Launch a Water-Propelled Satellite into Deep Space

#51

Post by DrStalker »

tocomment wrote: post #44
InclinedPlane wrote: post #28

Earlier quoted context omitted.

In a word: no. It generates a very minute amount of thrust. That's ok in the freefall of space because acceleration running 24/7 adds up fairly quickly. But these thrusters won't have a thrust to weight ratio higher than 1 so they can't feasibly be used for in atmospheric flight.

But couldn't a version be built on the same principles that has higher thrust?

Space is the only place where these engines are of any practical use; a combination of endless solar power, no friction, not having to stay up in the air by constantly fighting gravity and huge distances to travel means an engine with a tiny amount of thrust that can run for long periods of tiny with a tiny amount of fuel is useful.

On earth you're likely not even going to be able to overcome friction and start moving.

Re: Launch a Water-Propelled Satellite into Deep Space

#52

Post by DrStalker »

j-g-faustus wrote: post #32
jeremyjh wrote: post #25

Earlier quoted context omitted.

In the second sentence of the kickstarter page it says "a new rocket propulsion system powered by the Sun and propelled by water". I think that is pretty clear.

Clear for people in the know, I guess. But suppose I had a Kickstarter for a car on the same premises: "A revolutionary car powered by sunlight and water - fill up with water every now and then, and it will run forever". No further details. Would you buy? I think it's a very small percentage of the world that would know off the bat why "sun and water" could work for a spacecraft, but not for a car. I think some more…

They could do a little comparison of existing technologies:

Chemical rockets - put fuel and oxidizer together, burn them, resulting gas is shoved out the back and pushes the rocket forward.

NERVA - reaction mass is heated by a nuclear heat source, resulting gas is shoved out the back and pushes the rocket forward.

Ion thruster: reaction mass (such as xenon) is charged electrically using a grid and the resulting ions are shoved out the back and pushes the rocket forward.

CAT: reaction mass (such as water) is charged electrically using a glass bottle thingy and the resulting plasma is shoved out the back and pushes the rocket forward.

Shove that in an infographic and you can get the basic concept across to someone who knows high-school physics and sound convincing to people that don't even have that level of background knowledge.

http://en.wikipedia.org/wiki/NERVA http://en.wikipedia.org/wiki/Ion_thruster

Re: Launch a Water-Propelled Satellite into Deep Space

#53

Post by DrStalker »

el_shayan wrote: post #12

Why does it feel so much like a scam?

Because they don't explain the technology very well.

It looks similar to an ion thruster which is a technology already in use in space for situations you have plenty of power from solar panels, a long way to go to get somewhere, and your biggest concern is saving on weight by not carrying much fuel.

I don't see any fundamental reason it can't work, just questions as to how well it will work and if it will be better than existing technology.

Re: Launch a Water-Propelled Satellite into Deep Space

#54

Post by andrewfong »

noonespecial wrote: post #50
guiambros wrote: post #49

Earlier quoted context omitted.

I just attended a meet-up this evening with Slava Rubin, Indiegogo's CEO, and that was one of the topics he covered during his talk. The psychology of crowdsourced projects is fascinating. Basically the analogy is that if you want to raise 100, you set your goal to 50, and will probably end up with 120. Now if you set your goal to 100, you may end up with 20 and a failed campaign. Same project, same pitch, same perks…

"People only back winners." If people think that there's no way they'll ever reach that ambitious goal, they won't contribute, so there will be no way they'll ever reach that ambitious goal.

The irony is that Kickstarter's design ensures you won't lose any money backing a loser. In theory, backing a loser should be a risk-free proposition, but folks clearly don't see it that way.

Re: Launch a Water-Propelled Satellite into Deep Space

#55

Post by Wingman4l7 »

guiambros wrote: post #49
Wingman4l7 wrote: post #36

Earlier quoted context omitted.

True, but their original goal was 4x this amount.

I just attended a meet-up this evening with Slava Rubin, Indiegogo's CEO, and that was one of the topics he covered during his talk. The psychology of crowdsourced projects is fascinating. Basically the analogy is that if you want to raise 100, you set your goal to 50, and will probably end up with 120. Now if you set your goal to 100, you may end up with 20 and a failed campaign. Same project, same pitch, same perks…

Sounds like a really interesting talk -- do you know if it was recorded & posted anywhere?

Re: Launch a Water-Propelled Satellite into Deep Space

#56

Post by dnautics »

guiambros wrote: post #49
Wingman4l7 wrote: post #36

Earlier quoted context omitted.

True, but their original goal was 4x this amount.

I just attended a meet-up this evening with Slava Rubin, Indiegogo's CEO, and that was one of the topics he covered during his talk. The psychology of crowdsourced projects is fascinating. Basically the analogy is that if you want to raise 100, you set your goal to 50, and will probably end up with 120. Now if you set your goal to 100, you may end up with 20 and a failed campaign. Same project, same pitch, same perks…

I'm trying to figure out how to hack this psychology. I'm starting at 1/10 what I NEED, and running it into a phase II. That way we can declare an initial victory to capture the 'people like to back a winner' and then leverage the donor network to go the whole way.

Re: Launch a Water-Propelled Satellite into Deep Space

#57

Post by vastinfest »

This is a very cool idea indeed.

I looked over their Kickstarter and link to CAT engine itself, but only got confused. How are they going to change direction of the craft itself (I'm not sure what's the proper "space" terminilogy for "turning left or right is")? Or that is not needed?

Re: Launch a Water-Propelled Satellite into Deep Space

#58

Post by XorNot »

gus_massa wrote: post #33
acjacobson wrote: post #29

Earlier quoted context omitted.

While I am no expert in chemistry he mentioned that one of the benefits of using water was the fact that it is in a liquid state and thus you could effectively store more energy within a finite amount of space. At least one of the noble gases (argon) does not compress down to a liquefied state, so perhaps that applies to the others? Large compression tanks are also quite heavy, so perhaps that is a consideration too.

The page is not very clear. The energy comes from the solar cells. They are using the water to store mass, no energy. It’s (probably) easier to store a lot of mass of water as a liquid than a lot of mass of Xenon because you must compress it a lot. The idea is that to accelerate in one direction, you must push something in the opposite direction. They will convert the water into plasma (imagine very hot ionized water…

The other benefit is that you can find more water in space - it's harder to find argon and harder still to put it in a usable form.

They're almost certainly thinking of what you could with ion thrusters, the sun (or plutonium) and some of the icy bodies in the outer solar system.

Re: Launch a Water-Propelled Satellite into Deep Space

#59

Post by XorNot »

vastinfest wrote: post #57

This is a very cool idea indeed. I looked over their Kickstarter and link to CAT engine itself, but only got confused. How are they going to change direction of the craft itself (I'm not sure what's the proper "space" terminilogy for "turning left or right is")? Or that is not needed?

In space you can just spin a gyroscope faster or slower to rotate. No wind-resistance means you don't need a particularly heavy gyroscope to do it even.

Re: Launch a Water-Propelled Satellite into Deep Space

#60

Post by ramblerman »

andrewfong wrote: post #54
noonespecial wrote: post #50

Earlier quoted context omitted.

"People only back winners." If people think that there's no way they'll ever reach that ambitious goal, they won't contribute, so there will be no way they'll ever reach that ambitious goal.

The irony is that Kickstarter's design ensures you won't lose any money backing a loser. In theory, backing a loser should be a risk-free proposition, but folks clearly don't see it that way.

If you define a loser as a kickstarter that doesn't reach 100% funding, you're right

The OP you're responding to though defined a loser as someone who has unattainable goals in the eyes of the people. In which case you can certainly lose your money.

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