DARMSTADT, Germany (TIP): The signal broke a seven-hour wait of agonising intensity and sparked scenes of jubilation at the European Space Agency’s mission control in Darmstadt. The team in charge of the Rosetta mission achieved what at times seemed an impossible task by landing a robotic spacecraft on a comet for the first time in history.

The moment the tension broke came shortly after 1600 GMT when the Philae called home. “We are there. We are sitting on the surface. Philae is talking to us,” said a jubilant Stephan Ulamec, Philae lander manager at the DLR German space centre. “We are on the comet.” Andrea Accomazzo, the Rosetta flight operations director, added: “We cannot be happier than we are now.” But celebrations were tempered by the later discovery that the probe’s two harpoons had not fired to fasten the craft down in the ultra-low gravity. Scientists now think the probe may have bounced after first coming into contact with the surface.

Ulamec said: “Maybe today we didn’t just land once, we landed twice.” The safe, if precarious, touchdown of the lander gives scientists a unique chance to ride onboard a comet and study from the surface what happens as its activity ramps up as it gets closer to the sun. The first images beamed back from the lander’s descent revealed a dramatic landscape of pits and precipices, craters and boulders. However, there have been gaps in its radio link with the orbiting Rosetta mothership. The £1bn ($1.58bn) Rosetta mission aims to unlock the mysteries of comets, made from ancient material that predates the birth of the solar system. In the data Rosetta and Philae collect, researchers hope to learn more of how the solar system formed and how comets carried water and complex organics to the planets, preparing the stage for life on Earth.

Space agencies have sent probes to comets before, but not like this. In 1986, Nasa‘s Ice mission flew through the tail of Halley’s comet. In 2005, the agency’s Deep Impact spacecraft fired a massive copper block at comet Temple 1. But none before now has landed. The feat marks a profound success for the European Space Agency (ESA), which launched the Rosetta spacecraft more than 10 years ago from its Kourou spaceport in French Guiana. Since blasting off in March 2004, Rosetta and its lander Philae have travelled more than 6bn kilometres to catch up with the comet, which orbits the sun at speeds up to 135,000km/h. “We are the first to do this, and that will stay forever,” said Jean Jacques Dordain, director general of the ESA. Matt Taylor, a Rosetta project scientist, who had selected an extremely colourful shirt for the event, revealed an impressive – and brave – tattoo of the lander on the comet’s surface.

A TIMELINE OF COMET PROBE’S 10-YEAR JOURNEY

March 2, 2004: Europe’s unmanned probe Rosetta takes off from Kourou, French Guiana, after a series of delays, including an abandoned January 2003 launch window because of a rocket problem.

February 25, 2007: Rosetta carries out a close flyby of Mars. European Space Agency’s mission control breaks out in applause after the end of 15 tense minutes of radio silence as the craft passes behind the Red Planet.

September 5, 2008: Probe successfully passes close to an asteroid 250 million miles from Earth. The spacecraft loses its radio signal for 90 minutes as planned during the flyby of the Steins asteroid, also known as Asteroid 2867.

July 10, 2010: Between Mars and Jupiter, Rosetta transmits its first pictures from the largest asteroid ever visited by a satellite after it flies by Lutetia as close as 1,900 miles (3,200 kilometers). It is the closest look to date at the Lutetia asteroid.

January 20, 2014: Waking after almost three years of hibernation, Rosetta sends its first signal back to Earth. Systems had been powered down in 2011 to conserve energy, leaving scientists in the dark for 31 months.

August 6, 2014: Rosetta swings alongside comet 67P/Churyumov-Gerasimenko somewhere between the orbits of Mars and Jupiter.

November 12, 2014: The probe releases the Philae lander and it drops to the comet’s surface. Seven hours later, Philae touches down on the comet.