"Safely on the surface of Comet 67P"

A gadget-packed landing vehicle the size of a washing machine sent its own confirmation back to Earth on Thursday morning that it had landed safely -- after a couple of attempts -- and come to rest on the surface of a comet hurtling through space.

"Rosetta's lander Philae is safely on the surface of Comet 67P/Churyumov-Gerasimenko, as these first two CIVA images confirm," said a message on the European Space Agency's website posted as the caption to a high-resolution composite image of the Philae lander itself sitting on the icy comet's surface.

ESA's six-month mission to land on the surface of a comet for the first time ever culminated Wednesday, when the Rosetta probe launched the Philae lander toward the comet's surface. ESA knew it had touched down, but then data showed it had bounced, and they lost contact with the lander as expected due to the rotation of the comet before a stable landing could be confirmed Wednesday.

Knowing that a set of harpoons meant to secure the lander onto the comet's surface had failed, it was a tense wait overnight for the new telemetry showing that Philae had come to an eventual stable landing.

"Yesterday was exhausting! I actually performed 3 landings,15:33, 17:26 & 17:33 UTC," said a tweet on the Philae lander's official account Thursday morning. The account is managed by ESA staff at the European Space Operations Center in Darmstadt, Germany, but messages are posted in the first-person -- humanizing the high-tech lander which is now zooming through space aboard the comet some 317 million miles from Earth.

About half an hour later, the photo of the lander sitting on the comet was revealed.

As expected, CBS News space consultant William Harwood reported the Philae lander hit the two-and-a-half-mile-wide comet at a walking pace on Wednesday -- a bit more than 2 mph -- around 10:35 a.m. EST (GMT-5). Radio signals confirming touchdown reached flight controllers in Darmstadt 28 minutes later.

A cold gas thruster was programmed to fire at the moment of landing to help push Philae down while two harpoons shot into the soil to anchor the spacecraft in place. The harpoons and ice screws on the bottom of each landing leg were needed to help keep the spacecraft from bouncing off in a gravity field 100,000 times weaker than Earth's.

But the thruster system did not pressurize during overnight activation and engineers confirmed it did not fire during landing. In addition, the harpoons apparently failed to deploy as planned to anchor the lander on the surface.

"It's complicated to land on a comet," said Stephan Ulemac, the Philae landing team director. "And it's not only complicated to land there, it's also, as it appears, very complicated to understand what has happened during this landing. What we know is we touched down, we landed at the comet at the time when you all saw us cheering. We had a very clear signal there, and we also received data from the lander, housekeeping data and also science data.

While comets have been studied from afar by a variety of U.S. and European spacecraft, Rosetta and Philae represent the first attempt to fly in tandem with a comet as it approaches the sun and to drop a probe to its surface for in situ observations.

"Rosetta is the sexiest science mission, the sexiest space mission that's ever been," mission scientist Matt Taylor said earlier. "We're going to ride alongside this comet, we're going to have a ringside seat as we go from this rather inert object now through perihelion, that's closest approach to the sun next year, and as it starts to move away from that sun. ... It's going to be an awesome ride."

Philae is equipped with 10 sophisticated instruments and cameras. A 360-degree panorama was planned to give scientists a detailed look at the landing site, along with microscope views of the soil directly beneath the lander.

Assuming it will not displace the lander in the absence of its anchors, a drill will penetrate a foot below the surface to collect pristine material for chemical analysis. Other instruments will sample the dust given off by the comet, study its internal structure and monitor how it changes as 67P moves closer to the sun.

Rosetta, meanwhile, will relay Philae's data back to Earth and carry out science observations of its own using a suite of 11 cameras and other instruments. ESA hopes to operate Rosetta through the end of 2015 to characterize the comet's behavior as it approaches the sun and then begins heading back out into deep space.

But that assumes Philae is healthy and remains in place on the comet's frigid, low-gravity surface.

NASA contributed three instruments to Rosetta and relayed telemetry to ESA from the agency's globe-spanning Deep Space Network. Jim Green, director of planetary science at NASA headquarters, could barely contain his excitement.

"How audacious!" he exclaimed. "How exciting! How unbelievable, to be able to dare to land on a comet, to take that step that we have all wanted from a scientific perspective. this mission that ESA has produced and given aback to the world in this venue has allowed us all to participate in that great adventure. We should relish that moment."

Calling the Rosetta mission and Philae's landing "the start of something important," Green said "it's our destiny to move off this planet. And this is the kind of step that we must do. ESA, thank you from the bottom of my heart for a wonderful experience. And the science will be marvelous!"

Discovered in 1969, 67P/Churyumov-Gerasimenko circles the sun in an elliptical orbit extending nearly 500 million miles from the sun at its far point -- beyond the orbit of Jupiter -- to a point between the orbits of Earth and Mars some 115 million miles from the sun. The comet measures 2.5 miles across and rotates every 12.4 hours, taking about 6.5 years to complete one orbit.