Robert Bonitz of NASA’s Jet Propulsion Laboratory has been working on the Phoenix Mars Lander’s robotic arm for a long time — the arm was originally created for the ill-fated Mars Polar Lander in fact.

When the Phoenix Mars Lander was raised from the ashes of that failure, Bonitz began working on the arm again, this time for the lander to use to dig through the permafrost believed to underlie Mars’ arctic regions.

Phoenix project manager Barry Goldstein made a deal with Bonitz, who is an expert parachutist, in the early stages of the mission, about four-and-a-half years ago, that if Phoenix landed safely on the surface and completed its 90-day mission, he would do a tandem jump with Bonitz.

A few days after the bet, a meeting for Sept. 14, 2008 showed up on Goldstein’s network calendar, courtesy of Bonitz. But Goldstein didn’t think too much of it, considering how far away the date was at the time, he told reporters after a press briefing at JPL today.

Needless to say, after Sunday’s picture-perfect landing and the excellent performance of the spacecraft so far, Goldstein is becoming a little apprehensive about making that deal (personally, I can’t blame him). Whether Goldstein is going to follow-through on the deal hasn’t been decided yet — after all, the lander is only three sols (or Martian days) into its mission. So stay tuned come September though, for news of parachuting NASA scientists. And make sure never to enter into bets with expert jumpers.