Phobos Mission?

> >How is a mass supposed to just hang up there 30 - 50 m off the
> surface of Phobos? Why? Is this really a NASA document?
>
> If the mass is tethered on the far side of Phobos, and forced to
> co-orbit (in a higher-but-slower track round Mars), then there would be
> a net tension on the cable(s), just like there would be on an asteroid
> tethered at the "far" end of an Earth orbital tower, beyond the
> geosynchronous point. At some altitude the tension on the tether will
> balance the local gravitational attraction of Phobos...but my (early
> morning) spreadsheet for this case suggests that altitude is nearer
> 3.2km above the surface of Phobos and not lower.
>