It looks like space buffs' plan to push an aged NASA space probe into a new orbit has come up against a deal-breaker. Weeks after making contact with the International Sun-Earth Explorer-3, or ISEE-3, the group of citizen scientists has learned the tanks on the spacecraft are apparently empty of nitrogen, the New York Times reports. Since the gas is required to fire the thrusters that would alter the probe's trajectory—the group had planned to boot it out of its heliocentric orbit and into one where it could better communicate with Earth—it's a massive problem. "Odds are, there is nothing we can do," says Keith Cowing, a leader of the reboot project. "Without that, you don't have a rocket."
The group fired the thrusters just last week, but when they tried to activate the thrusters yesterday and Tuesday they just sputtered. Space.com reports scientists initially thought a "valve malfunction" could be at fault, but Cowing last night wrote they were instead pinning the blame on a lack of nitrogen, which is needed to push the fuel, called hydrazine, to the thrusters. As for why the thrusters appeared to work last week, that was "probably the result of residual hydrazine that was already in the system that had pressure," says Cowing, per Space News. He says ISEE-3 is now operating in science mode, meaning it's sending data back to Earth that'll be accessible for the next three months or so. After that, it'll be so far from us that communicating with it will become cost-prohibitive.