This historic landing of a spacecraft on a comet turned out to be not one but three landings as the craft hopped across the surface. Because of the failure of a thruster that was to press it against the comet’s surface after touching down, the European Space Agency’s Philae lander, part of the $1.75 billion Rosetta mission, bounded up more than half a mile before falling to the surface of Comet 67P/Churyumov-Gerasimenko again nearly two hours later, more than half a mile away. That is a considerable distance across a comet that is only 2.5 miles wide.

Philae then bounced again, less high, and ended up with only two of its three legs on the surface, tipped against a boulder, a wall of rock or perhaps the side of a hole. “We are almost vertical, one foot probably in the open air — open space. I’m sorry, there is no air around,” Jean-Pierre Bibring, the lead lander scientist, said at a news conference on Thursday.

In the skewed position, Philae’s solar panels are generating much less power than had been planned, and when its batteries drain in a couple of days, it may not be able to recharge. As the comet rotates once every 12 hours, the lander is receiving only about 1.5 hours of sunlight instead of the expected six to seven hours.

Despite the bumpy landing, Philae remained in contact with the Rosetta orbiter and performed its initial set of observations, including photographs of a cliff above the spacecraft. Stephan Ulamec, the lander’s manager, said he was reluctant to do anything requiring mechanical movement that might tip Philae onto its back. “We need to be very careful about deploying instruments,” he said.

Later in the day, however, scientists announced via Twitter that they would proceed with plans to use Philae’s Mupus instrument (short for Multipurpose Sensors for Surface and Subsurface Science), which is to hammer a 14-inch-long hollow rod into the comet to measure properties including temperature, density and hardness. “We will deploy the Mupus penetrator for 2/3 of the max. length and then insert it,” the post said. “Should happen before midnight. Keep fingers crossed.”

Philae is the first spacecraft to land on a comet, a remarkable feat that will allow scientists to investigate one of the frozen leftovers from the formation of the solar system. When the touchdown signal arrived at the spacecraft operations center in Darmstadt, Germany, the celebrations started.

The lander had hit its landing target almost exactly, Dr. Bibring said. Dr. Ulamec reported that its speed at landing was about one meter per second, or 2.2 miles per hour, a leisurely walking pace.

But two harpoons that were to have secured Philae to the surface never fired. And so, with radio signals taking 28 minutes to travel the 316 million miles from Rosetta, as mission scientists were celebrating its landing, Philae was back in space; it had recoiled upward at a speed of 38 centimeters a second, or less than a mile per hour. With the weak gravitational pull of the comet, Philae traveled high and far before touching down gain.

The second bounce was smaller, with the lander leaving the surface at less than one-tenth the speed of the first bounce. “We have a better understanding now how we got there,” Dr. Ulamec said. “We still do not really know where.” Joel W. Parker, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who has worked on the Rosetta project, said scientists had much to learn from the lander’s signals. “They may have enough data to sift through from the various instruments to do a ‘C.S.I. Philae’ and piece it all together,” Dr. Parker said by email.

Dr. Bibring took some umbrage at suggestions that the landing was a failure, pointing to the wealth of scientific data that has already been collected and how much had gone right.

It’s gorgeous where we are,” he said.