海角大神

The European Space Agency鈥檚 Rosetta spacecraft crashed into the comet it has spent its life faithfully studying on Friday morning 鈥� intentionally.

The European Space Agency (ESA) launched Rosetta in 2004 to study the composition of comets, a lesson that scientists hope will contribute to their understanding of how the planets, including Earth, were formed.

Over the past 12 years, Rosetta has followed comet 67P/Churyumov-Gerasimenko across more than 3.7 billion miles of space, sending data and photos back down to Earth. After finally reaching the comet in 2014, Rosetta released Philae: a smaller probe that performed the first-ever comet landing.

During their tour of the comet, Rosetta and Philae provided a wealth of new data to scientists.

"We have learned a lot about comets,"聽ESA鈥檚 Markus Bauer told 海角大神 in February.聽"We had to learn for example that the water on comets is not the same water as in Earth鈥檚 oceans. Our water must therefore have come from other sources. We have discovered organic compounds which play a key role in the prebiotic synthesis of amino acids and sugars, which are the ingredients for life."

And, as Manuela Braun of the German Aerospace Center told the Monitor鈥檚 Jason Thomson, scientists previously expected comets鈥� surfaces to be soft and fluffy. But as Rosetta and Philae鈥檚 missions have proven, a comet鈥檚 composition can be 鈥渧ery heterogeneous鈥� with hard surfaces.

鈥淚t will be hard to see that last transmission from Rosetta come to an end,鈥� Art Chmielewski, of NASA鈥檚 Jet Propulsion Laboratory and project manager for the US Rosetta, said聽. 鈥淏ut whatever melancholy we will be experiencing will be more than made up for in the elation that we will feel to have been part of this truly historic mission of exploration.鈥澛�

But Rosetta鈥檚 fatal crash course was not the only option.聽

鈥淲e could have abandoned it in space or let it bounce off the comet and just switched it off. It wouldn鈥檛 have created any problem,鈥� Andrea Accomazzo, the ESA's spacecraft operations manager, . 鈥淟anding is more a psychological thing.鈥�

However, Rosetta was set to end one way or another. The comet 67P is racing toward the outer solar system 鈥� a destination too far away from the sun for a piece of solar-powered machinery.

And even in its final hours, Rosetta sent crucial information back down to Earth by taking close-up photos and 鈥渙nce-in-a-lifetime measurements鈥� of comet 67P. Specifically, Rosetta focused on one-meter high lumps, or 鈥済oose bumps,鈥� in an open pit of the comet, which have puzzled scientists for years.

鈥淲e want to go out at the peak of capability. We don鈥檛 want a comeback tour that鈥檚 rubbish,鈥� project scientist Matt Taylor told Reuters. 鈥淲e will end in a very rock-and-roll fashion.鈥�

This report contains material from Reuters.