Travel to "gravity holes'

[Dr Mordrid]

AKA Lagrange points - positions in space where the gravity of Earth, Sun and moon cancel out.

Link....

Why future astronauts may be sent to 'gravity holes'

With doubts brewing about the feasibility of returning to the moon or aiming straight for Mars, another option has emerged for our next steps into space: gravitational "sweet spots" called Lagrange points that lie at least 1 million kilometres away.

A White House-commissioned task force charged with reviewing NASA's spaceflight plans is considering recommending this as part of a "deep space" option in a report expected soon. But why send humans to empty space?

Lagrange, or Lagrangian, points are great swathes of space where the gravitational acceleration from the Earth and the sun are exactly equal, letting objects stick there with very little effort.

Because they're far from warm stars and planets, they make useful havens for ultra-cold telescopes that measure fluctuations in the temperature of deep space.

The Wilkinson Microwave Anisotropy Probe (WMAP), which measures radiation from the big bang, lives at a Lagrange point called L2 more than 1 million kilometres away. The successor to the Hubble Space Telescope, the massive James Webb Space Telescope, will also be sent to the spot, which lies in line with the sun and Earth (see illustration).
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[Jammrock]

L2 could be a great staging place for missions to Mars.

[Dr Mordrid]

There is already talk of SpaceX creating an enhanced Dragon for beyond LEO missions. The basic structure was already designed for lunar and the heat shields forerunner PICA has already been used for nearly 30,000 mph re-entries (advanced form for Dragon is called PICA-X) .

That and the recently announced Raptor LH2 second stage mounted on a Falcon 9 Heavy would create the also newly talked about Falcon 9 Heavy H: 45-50 metric tons to LEO.

Not the rocket you'd use for pure LEO missions, but one helluva kick in the ass for going to L2. Do 2-3 launches and assemble the habs etc. in LEO and you have a nice interplanetary vehicle.

One more and you can put a fuel depot at L2 and go most anywhere.

[Evildead666]

Could some of those points be reached by the Earth 'dropping "stuff" behind it' and then having them speed up when they get to the right point ?

i.e just sitting still until the earth has gone round the sun to the other side.

edit : L3, L4, and L5 ?

[KRSESQ]

Could some of those points be reached by the Earth 'dropping "stuff" behind it' and then having them speed up when they get to the right point ?

i.e just sitting still until the earth has gone round the sun to the other side.

edit : L3, L4, and L5 ?

IIRC if you try to "hold station" in Earths orbit and wait for the trailing L point to reach you, you are essentially decelerating below Earth-orbital speed, causing you to drop toward the sun and in doing so accelerate into an orbital path that takes you to the leading L point. Likewise accelerating in the direction of Earth's orbital path takes you away from the sun, placing you in a longer orbit that takes you to the trailing L point. Basically the opposite of what you said but the same result.

(Unless I TOTALLY misunderstood what Carl Sagan said in Cosmos.)

Kevin

[Evildead666]

Hold position with thrusters...either way.

Computer controlled to keep you in that point until the L3,4,5 point come round, and then stick with it.

[Dr Mordrid]

L points are treated like quasi-bodies in orbit, so you shoot for them as if they were a planetoid or asteroid and go into orbit around its center. You stay there until you do a burn to go somewhere else. Essentially, they're like a geostationary orbit.

Since some of the L points are large enough to have their areas of influence rather close to others or real world bodies it takes little fuel to move from one to another, like hopping from one rock in a stream to another. Also; other bodies like Mars and Venus have their own L points, and often you can hop from an Earth L point to another bodies. VASIMR would be great for this kind of mission as its fuel mass is so low as to not really affect cargo needs.

There are several missions at L2 already and the huge (6,200 kg/14,000 lb) James Webb Space Telescope (IR scope, not visible light) is due to go there in 2014. L2 is good for an IR deep space observatory because Earth shades it from the sun, which is bad for its cryogenic detectors.

http://www.jwst.nasa.gov/

IMO the L points should be one of our short term manned mission goals because they can be used as jumping off points to most everywhere else in the inner solar system.

L points vs. gravity


Mockup of the James Webb Space Telescope


Diagram of JWST (note that it'll orbit L2)