[X] My Assistant

[karolp]

Another one emerging from the vast Planetary Radio archives. Emily in her inpersonation of Sandy Moondust sitting on MER-B before launch (check the Astrobots project if unfamiliar with that ) said that it was to be launched on a heavier vehicle than MER-A, namely Delta 2 heavy with strap-ons 6" thicker than a regular Delta 2. Why is that so? Why launch two identical rovers on two different rockets? And - was it also the case with the Viking and Voyager pairs?

[dvandorn]

IIRC, they had to launch the Deltas from the same pad, so there had to be a separation of several weeks between the launches. At the beginning of the launch window to reach Mars in 2003, the amount of energy required to get a MER to Mars was within the capabilities of the more basic Delta II configuration. But by the end of the launch window, the energy requirement was enough greater that the Heavy configuration was required.

The problem, I believe, was more that the MERs stretched the ability of the Delta II right up to its limits. You oculdn't send anything much heavier than the MER package to Mars on a Delta II in any configuration. They nearly maxed out the launch and EDL systems with the MERs.

-the other Doug

[mcaplinger]

IIRC, they had to launch the Deltas from the same pad, so there had to be a separation of several weeks between the launches.

No. There are two pads at Complex 17. MER-A went from one and MER-B from the other. The end of MER-A's launch window and the start of MER-B's were only about a week apart.