英语新闻:64亿公里的等待 人类探测器首次登陆彗星

发布时间: 2014-11-15 14:49   来源:
关键词: 英语新闻:64亿公里的等待 人类探测器首次登陆彗星

英语新闻:64亿公里的等待 人类探测器首次登陆彗星

A European robot probe has made the first, historic landing on a comet, but its status is uncertain after harpoons failed to anchor it to the surface.

The "first" landing on Comet 67P/Churyumov-Gerasimenko was confirmed at about 1605 GMT.

There were cheers and hugs at the European Space Agency (Esa) mission control in Darmstadt, Germany, after the signal came through.

Director general Jean-Jacques Dordain described it as "a great great day, not only for Esa, but... I think for the world". He described the landing as "a big step for humancivilisation".

Further analysis is needed to fully understand the status of the probe, known as Philae.

However, Lander project manager Stephan Ulamec told the BBC that at last radio contact with the probe, he believed it to be in a stable configuration.

"This is the indication right now," he explained. "We really have to wait until tomorrow morning and then we will know a lot more."

Early data started to come back from instruments, and one team could see that the lander had sunk about 4cm (1.5 inches) into the surface, suggesting a relatively soft top layer.

But shortly after, engineers could see that the harpoons, designed to fasten the spacecraft to the 4km-wide (2.5 miles) ball of ice and dust, had not fired as planned.

In a later media briefing, Dr Ulamec said: "What we know is we touched down, we landed at the comet at the time when you all saw us cheering and when it was announced.

"We had a very clear signal there; we received data from the landing - housekeeping and science data. That's the good news."

But then Dr Ulamec delivered the "bad news". He said telemetry from the craft suggested it might have drifted off the surface after landing and started to turn. This subsequently came to an end, which the German Space Agency official interpreted as a possible "second landing" on Comet 67P.

In fact, even later data would indicate that the Philae robot may have bounced twice, taking a full two hours to come to a rest.

This bouncing was always a possibility, but had been made more likely by the failure of the harpoons to deploy, and the failure of a thruster intended to push the robot into the surface.

Pictures from the surface have been retrieved at Earth and are being processed in preparation for release.

Scientists were initially elated following the confirmation of a landing.

But the news about the unanchored state of Philae has cast a shadow over the celebrations.

The mission team must decide if the harpoons can now be commanded to fire without unsteadying the robot still further.

What is clear is that Philae touched down very close to the targeted zone on the head of the rubber-duck-shaped comet.

If Philae remains stable and can be properly secured, it will engage in several months of science experiments on 67P.

It will take pictures of the cometscape and analyse the surface chemical composition.

Scientists are hoping 67P's surface materials will hold fresh insights into the origins of our Solar System more than 4.5 billion years ago.



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