Just send already-dead astronauts. You will need to launch a lot less consumables, life support, shielding, and soft-landing equipment. The science return will be impacted, but not by much.
Deccelerating something from orbital velocity is just as difficult as accelerating it to orbital velocity in the first place, except you've expended all your fuel already. Much easier to use the atmosphere.
Mining water from an extraterrestrial body, with or without humans, is science fiction at the moment. I don't see how you can make 10 year plans that involve this.
As to passenger-less travel, I'm all for it. It's so much cheaper, faster, safer, and efficient that I don't see why anyone bothers with people.
Let's list them - getting a large enough can to space (Apollo and Dragon are too small for an 8 month voyage with all the consumables needed) - protecting the humans from radiation during the 8 month voyage - slowing down (can be done with fuel, but increases launch costs a LOT) - landing (can be done with fuel, but increases launch costs a LOT) - generating fuel and consumables on Mars - handling contingencies
Submarines that are capable of 8 month voyages mass 10,000 tons. Fancy lifting that into space?b
It's using proven technology with no exotic materials that they had to develop themselves. They're not even using the more efficient Hydrogen as fuel - they're using the less efficient but much more reasonable kerosene. This is what allowed them to develop a reasonable launcher for better-than-reasonable prices.
However, it's a far cry from round trips to Mars. That needs a lot of exotic development and is in uncharted territory, unlike everything else that SpaceX has done before. Musk's promises are worthless here unless he can see into the future.
This is wrong, you can move more than one unit of energy with a heat pump per unit of energy invested. In fact it is more efficient to heat with an air conditioner than with an electric heater.
Yet religions are the only ones to claim divine sponsorship of their ideas, and to try to enforce them. The only organizations that come close are states, and they tend to interfere a lot less in their citizen's private lives.
The human race is a few million years old, science and technology a few hundred years old. Why the hurry? Let's tackle the Sun dying out in a couple of billion years after we have some more experience. That leaves us another two billion years to test out newly-developed technology.
108 years ago: first aircraft made of wood and cloth, driven by propellers 67 years ago: jet fighters 57 years ago: subsonic jet airliners made of aluminum 35 years ago: supersonic jet airliners 20 years ago: bigger, better subsonic jet airliners 10 years ago: bigger, better subsonic jet airliners now: bigger, better subsonic jet airliners made of composites
Eventually the exponential growth in technology slows, and we are left with incremental improvements. Don't let Moore's law blind you, it only holds for semiconductors, and not for long there either.
1/1000th of a G is currently unreachable (for a 100 ton spacecraft you'd need 1000 N thrust, current engines provide 5 N), nor is a suitable power source forthcoming. However this may change in a couple of decades as research continues.
They thought about it, and it turned out that ion engines and fission reactors have horrible thrust/mass ratios which would mean trips would take a very long time, though they would use a lot less fuel like chemical rockets.
If you can increase an ion thruster's thrust by quite a lot, and downsize a fission reactor by quite a lot, we can talk again.
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This way they were actually able to get it done.
Just send already-dead astronauts. You will need to launch a lot less consumables, life support, shielding, and soft-landing equipment. The science return will be impacted, but not by much.
Deccelerating something from orbital velocity is just as difficult as accelerating it to orbital velocity in the first place, except you've expended all your fuel already. Much easier to use the atmosphere.
Mining water from an extraterrestrial body, with or without humans, is science fiction at the moment. I don't see how you can make 10 year plans that involve this.
As to passenger-less travel, I'm all for it. It's so much cheaper, faster, safer, and efficient that I don't see why anyone bothers with people.
That adds a huge amount to the fuel load.
Let's list them
- getting a large enough can to space (Apollo and Dragon are too small for an 8 month voyage with all the consumables needed)
- protecting the humans from radiation during the 8 month voyage
- slowing down (can be done with fuel, but increases launch costs a LOT)
- landing (can be done with fuel, but increases launch costs a LOT)
- generating fuel and consumables on Mars
- handling contingencies
Submarines that are capable of 8 month voyages mass 10,000 tons. Fancy lifting that into space?b
SpaceX got one thing right: it's conservative.
It's using proven technology with no exotic materials that they had to develop themselves. They're not even using the more efficient Hydrogen as fuel - they're using the less efficient but much more reasonable kerosene. This is what allowed them to develop a reasonable launcher for better-than-reasonable prices.
However, it's a far cry from round trips to Mars. That needs a lot of exotic development and is in uncharted territory, unlike everything else that SpaceX has done before. Musk's promises are worthless here unless he can see into the future.
This isn't science, it's PR.
This is wrong, you can move more than one unit of energy with a heat pump per unit of energy invested. In fact it is more efficient to heat with an air conditioner than with an electric heater.
Yet religions are the only ones to claim divine sponsorship of their ideas, and to try to enforce them. The only organizations that come close are states, and they tend to interfere a lot less in their citizen's private lives.
This "Love God" rule is completely pointless.
No, it's "religion".
Try deleting one of the other and seeing whether the statement still holds.
Religion is born... from FEAR and IGNORANCE.
And also the other way around:
Religion breeds fear and ignorance.
It's so beautifully symmetric.
Well, Curiosity uses a parachute, so it's probably not too heavy for it.
A small rover or lander can only carry a small amount of instruments. If you want to do serious science, you need a reasonable number of those.
It's too large for airbags.
Progress in fuel efficiency and aircraft size will slow down and eventually stop as well.
Well, let's start worrying about it a billion years before it happens.
Worrying about it now is like a 20 second old fetus planning its retirement.
btw, in 4 billion years are descendants may well not be human. Are you sure you want them to live? Maybe they'll all be monsters.
How old are you?
The human race is a few million years old, science and technology a few hundred years old. Why the hurry? Let's tackle the Sun dying out in a couple of billion years after we have some more experience. That leaves us another two billion years to test out newly-developed technology.
108 years ago: first aircraft made of wood and cloth, driven by propellers
67 years ago: jet fighters
57 years ago: subsonic jet airliners made of aluminum
35 years ago: supersonic jet airliners
20 years ago: bigger, better subsonic jet airliners
10 years ago: bigger, better subsonic jet airliners
now: bigger, better subsonic jet airliners made of composites
Eventually the exponential growth in technology slows, and we are left with incremental improvements. Don't let Moore's law blind you, it only holds for semiconductors, and not for long there either.
Even if we do spread to other worlds, systems, and galaxies we're doomed as a species. Who cares if it happens in 4 billion or 100 billion years?
Endeavour is about 20 years old, if it can take it, so can your car.
1/1000th of a G is currently unreachable (for a 100 ton spacecraft you'd need 1000 N thrust, current engines provide 5 N), nor is a suitable power source forthcoming. However this may change in a couple of decades as research continues.
They thought about it, and it turned out that ion engines and fission reactors have horrible thrust/mass ratios which would mean trips would take a very long time, though they would use a lot less fuel like chemical rockets.
If you can increase an ion thruster's thrust by quite a lot, and downsize a fission reactor by quite a lot, we can talk again.