Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: IzzieC on 04/09/2017 14:35:07
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Xavier wants to know:
Why is nobody using the moon as a launch platform for spacecrafts?
What do you think?
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To launch something from the Moon you would have to have something there to launch. But just getting to the Moon means you have already done most the work needed to launch a spacecraft into deep space. If we had an established Moon colony, and it had the resources to build a spacecraft, then it would make sense to use the Moon as a base to launch said craft.
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Thread drift alert!
Back in the 70s, I recall reading a prediction that by the end of the century we should be able to see the lights of colonies on the moon, with the naked eye. I think it may have been in Adrian Berry's "The Next Ten Thousand Years". I apologise if I wrongly tag him as a false prophet.
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Thread drift alert!
Back in the 70s, I recall reading a prediction that by the end of the century we should be able to see the lights of colonies on the moon, with the naked eye. I think it may have been in Adrian Berry's "The Next Ten Thousand Years". I apologise if I wrongly tag him as a false prophet.
You musnt have your robot butler either then.
To get to the moon you would have to shift all the fuel and equipment there at present and theres no atmosphere to aid construction of spacecraft so theres no real benefit. To make the moon worth while a huge construction pod with atmosphere would be needed to allow construction unhindered.
There was much exitement about water being found there allowing for fuel production from a nuke source.
We could launch spacecraft, but to make it worthwhile we would need somewhere to go, and current propulsion is not fast so we have nowhere to go. We could manage mars just.
So basically a white elephant at present.
Why we havnt a base there i do not know, it would be surely cheaper than the space stations that have been built, and we could get a superb telescope built there, larger cheaper and better than hubble and its decendants. It would not be open to space debris collisions. Maintainence andd upgrades would be easy. You would not even need to land the transit vehicles.
And the other reason for a monbase is james cameron of alien films wanting to mine asteroids by landing them upon the moon .
Moon bases now !
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Just to add my two cents:
Where are we sending these spacecraft? And how would launching from the moon help?
If, in the not-so-distant future there is an active space-travel/transport industry, presumably Earth would be one node (we will want to send people and robots and perhaps raw materials from Earth, and we will want to bring precious metals, samples, etc. back to Earth.)
The moon doesn't seem like that much of a destination yet, but perhaps there could be a base there and people would go back and forth. For traveling anywhere except perhaps within the inner solar system, there really isn't much benefit to leaving from the moon rather than from the earth. The gravity well is still quite substantial to get off the surface of the moon, and then you still have to climb the rest of the way out of Earth's well. And if you are going to the outer solar system, climbing against the sun will be the primary challenge, and the moon doesn't help there at all.
Some have proposed building a base on one of the Martian moons, both of which are significantly smaller than our moon, and starting from a Martian orbit does make it significantly easier to send ships to the asteroid belt, and Jupiter (from which a slingshot maneuver can get you anywhere within the solar system if you time it right.)
Others say we should build in the asteroid belt. Maybe make a base on Ceres, which we know has water and organic matter and less than 20% the surface gravity of our moon, and is very close to some asteroids with high precious metal content.
Others argue that we should make bases closer to the sun to take advantage of the solar energy. Sending ships out into the cold, dark reaches of the outer solar system is probably not the best way to start. A large space station in orbit around Venus could be pretty awesome! Some even have suggested floating cities in the atmosphere of Venus (supposedly there is a certain altitude where the temperatures and pressures are not terribly far from liveable, but you would still need to have a perfectly contained system to keep the toxic/corrosive atmosphere out)...
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Here's someone "who wants to colonize the moon".
https://www.laboratoryequipment.com/news/2017/09/trump-picks-oklahoma-congressman-former-fighter-pilot-lead-nasa
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Just to add my two cents:
Where are we sending these spacecraft? And how would launching from the moon help?
If, in the not-so-distant future there is an active space-travel/transport industry, presumably Earth would be one node (we will want to send people and robots and perhaps raw materials from Earth, and we will want to bring precious metals, samples, etc. back to Earth.)
The moon doesn't seem like that much of a destination yet, but perhaps there could be a base there and people would go back and forth. For traveling anywhere except perhaps within the inner solar system, there really isn't much benefit to leaving from the moon rather than from the earth. The gravity well is still quite substantial to get off the surface of the moon, and then you still have to climb the rest of the way out of Earth's well. And if you are going to the outer solar system, climbing against the sun will be the primary challenge, and the moon doesn't help there at all.
The Moon has an escape velocity of 2.375 km/sec. Escape velocity from the Earth at the distance of the Moon is ~1.414 km/sec. However the Moon's orbital velocity is ~1 km per sec and anything launching from the Moon will carry that velocity, so it only needs an additional 0.414 km/sec once it escapes the Moon to escape the Earth. So launching from the Moon it only takes a delta v of 2.789 km/sec to escape Earth's gravitational pull vs 11 km/sec to do so from the surface of the Earth. (of course, As I mentioned above, if you have to lift that craft from the Earth to the Moon first, you lose all this advantage. )
There isn't any advantage over traveling between planets of the Inner solar system over traveling to ones in the outer solar system. Starting from Earth's Solar orbit, it takes a a total delta v of ~5.2 km/sec to intercept with Venus and match orbital velocities with it. To do the same for Mars requires 5.6 km/sec, only a 7.7% increase. But Mars' orbit is almost 90% further from Earth's than Venus is.
To make the same trip to Mercury requires a delta v of 17 km/sec, which is more than that required to make the same trip to Saturn (~16 km/sec).
It is actually takes more delta v to drop a probe into the Sun from Earth orbit that it does kick it out of the solar system entirely.
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A delta v of 5 km/s is beyond the ability of chemical rockets to carry a human on a 2-way journey, unassisted.
A delta v of 16km/s is beyond the capability of chemical rockets to carry a human on a 1-way journey, unassisted.
If you want assistance from gravitational slingshots, then you have to wait until the planets align in the right way, which means that humans will be hanging around and consuming food, water, energy & oxygen (- any that can be recycled). So basically, you are stuck with robotic missions, which can survive on solar power (inner Solar system) or radioactive decay (outer Solar system) while waiting for the balls to line up.
I'm afraid that for manned return missions, we will need something much more efficient than chemical fuels: space elevators, fusion power, ion drives, antimatter storage or warp drives. Of these, only ion drives have reached "working prototype" stage.