I think NASA should capture an asteroid and place it into a stable Lagrange point. The mass of the asteroid could provide resources, radiation shielding, and additional gravitational stability for other facilities/assets at the same Lagrange point.
If suitable engineering is done, stations could undock from the radiation shield and updated stations docked in place, so the investment in delta-v and materiel could be preserved.
Lagrange orbits aren't that great in the long run, and come with their own unique set of challenges (from en.wikipedia.org/wiki/Lagrangian_point#Mathematical_details):
"Although the L1, L2, and L3 points are nominally unstable, it turns out that it is possible to find (unstable) periodic orbits around these points, at least in the restricted three-body problem. These periodic orbits, referred to as "halo" orbits, do not exist in a full n-body dynamical system such as the Solar System. However, quasi-periodic (i.e. bounded but not precisely repeating) orbits following Lissajous-curve trajectories do exist in the n-body system. These quasi-periodic Lissajous orbits are what most of Lagrangian-point missions to date have used. Although they are not perfectly stable, a relatively modest effort at station keeping can allow a spacecraft to stay in a desired Lissajous orbit for an extended period of time. It also turns out that, at least in the case of Sun–Earth-L1 missions, it is actually preferable to place the spacecraft in a large-amplitude (100,000–200,000 km or 62,000–124,000 mi) Lissajous orbit, instead of having it sit at the Lagrangian point, because this keeps the spacecraft off the direct line between Sun and Earth, thereby reducing the impact of solar interference on Earth–spacecraft communications. Similarly, a large-amplitude Lissajous orbit around L2 can keep a probe out of Earth's shadow and therefore ensures a better illumination of its solar panels."
Earth-Moon L4 and L5 is still very unstable due to the Sun (and other planets).
Earth-Sun L4 and L5 is more stable, but almost useless as a waypoint; however there are already naturally captured asteroids (and a lot of dust) already there.
All orbits require station keeping in a dynamic solar system that is circling around a black hole.
If the asteroid has any water, station keeping won't require external fuel. If it doesn't, mass drivers could be used to toss chunks of the asteroid off and correct for instability (though that might create space debris if the velocity isn't enough).
By shielding, do you mean that astronauts could live inside or behind the asteroid, just using its mass between them and the sun? That would be pretty dark and cold. As far as I know, no asteroids have major magnetic fields.
I am totally with you on using the asteroids for materials, but I am not sure that they would provide useful gravity either. Even one of the largest near-earth asteroids, 433 Eros, only has a surface gravity of 0.0059 m/s^2. Is that useful?
By shielding, do you mean that astronauts could live inside or behind the asteroid, just using its mass between them and the sun?
I mean that the habitable modules would be located inside silos embedded within the asteroid, so that the living space would be entirely surrounded by radiation shielding mass.
That would be pretty dark and cold.
The problem in space is generally getting rid of heat. Vacuum is a great insulator, insulation material is effective and relatively cheap, and radiative cooling is fairly slow. The other thermal problem is exposure to direct sunlight. The asteroid as a shell of massive shielding would help in this regard.
The largest thing NASA has moved above low earth orbit since the early '70s is, what, Galileo? How many orders of magnitude are there between G and your asteroid?
Cassini was launched in 1997 and weighed over two and a half times what Galileo did (5712kg vs 2223kg). Still several orders of magnitude less than an asteroid.
Not yet, but perhaps in the near future. The National Space Society has a proposal up for capturing 99942 Apophis via gravitational slingshot, which would be fairly damaging if we managed to crash it.
Lets put it this way. The largest asteroid in the inner Solar system, Ceres has a mass of 1.3% of the moon.
The size of asteroid we are talking about here is likely to be closer to a container ship or maybe a small hill. Perhaps 1 millionth of the size/mass of Ceres at the most.
Why not halfway between us and the moon? It could be an easy-to-reach halfway point for the Moon, a refueling station and very-low-g launchpad other points, internet relay base, and also have commercial, industrial, and housing areas.
This could be an interesting new step in human modification of the environment - "orbitforming" (like terraforming?) a better solar system. It's like razing a hill to make way for farmland or better city building conditions.
An asteroid that's easy for vacationing billionaires, mining companies, and highly-pollutant industry to reach would be a great next step for humankind.
LEO is an orbit around Earth with an altitude between 160 kilometers (99 mi), and 2,000 kilometers (1,200 mi) The moon is on average 384,400 kilometers (238,900 miles) away. The Moon(ish) is where NASA is headed, LEO is what they're leaving behind.
Well, that was a big chunk of ice (comet core) and they stuck a bare fission reactor core in it to make a steam rocket. And they had robot swarms to mine/shape ice. It's a very cool book, though!
I don't know what the grandparent's point was, but I believe that kinetic weapons are exempt from space weapons treaties, hence the "Rods from God" satellite designs.
If suitable engineering is done, stations could undock from the radiation shield and updated stations docked in place, so the investment in delta-v and materiel could be preserved.