Probe That Landed on Comet May Not Be Secure Harpoons might have to be fired again By John Johnson, Newser Staff Posted Nov 12, 2014 3:50 PM CST 32 comments Comments The picture released by the European Space Agency was taken by Rosetta's Philae lander during its descent to the comet. (AP Photo/ESA) (Newser) – No matter what, the European Space Agency made history today with its astonishing feat of landing a spacecraft on a comet. But now the ESA has a simpler concern: Its Philae lander, about the size of a washing machine, might fall off. The main problem is that the lander's harpoons didn't fire upon landing and thus did not anchor the spacecraft onto the comet, reports Wired. Scientists are exploring the idea of trying to refire the harpoons. It wasn't the only glitch. As AP explains, the lander's downward thrusters didn't operate properly, which is perhaps part of the reason that ESA officials think the lander bounced. "Maybe we didn't just land once, we landed twice," says project manager Stephan Ulamec. It will take more analysis to figure out exactly what happened, reports the BBC, but the probe's first radio contact suggested that all was well for now. As ESA chief Jean-Jacques Dordain says, in an understatement for the ages, "It's complicated to land on a comet."