[X] My Assistant

[Bart]

Hi, I’ve been lurking here for a while, but this is my first post. The recent talk on the Uranus & Neptune orbiter forums about Galileo- vs. Cassini-style tours of the moons of the outer planets reminded me of an idea that I had a while ago.

Would it be possible to arrange a Cassini-style trajectory in the Earth-Moon system that would allow periodic visits of NEOs as they passed by? If you limited yourself to visits within 2-3 million km, you would have about one opportunity per year.

Lunar gravity assists should provide enough delta-v for the necessary plane changes, and the flyby orbits would have periods of ~100 days, allowing for a few assists between flybys.

If you could do close flybys of 5 different NEOs over 5 years without going more than 3 million km from Earth, that would seem like an ideal candidate for a Discovery mission.

The potential problem I see with this idea is that Earth’s Hill sphere is only ~1.5 million km, so you’d be spending a good part of each rev orbiting the Sun instead of the Earth. Would it be prohibitive either in terms of time or delta-v to get a spacecraft from a solar orbit 3 million km from Earth to a lunar return trajectory?

[djellison]

iirc Genesis used lunar flybys to line up for re-entry, and Contour used them I believe. Stereo will use them to send the two spacecraft in opposite directions as well.

Doug