Northern Ireland

Philae comet lander: Belfast astronomer hails reconnection

Prof Alan Fitzsimmons
Image caption Prof Alan Fitzsimmons provides telescopic research support to the Philae space mission team

A Belfast-based astronomer who assisted the Philae space mission has said it is "absolutely fantastic" that the lander has woken up and contacted Earth.

Philae was the first spacecraft to land on a comet last year, but its solar-powered battery ran flat within hours.

Prof Alan Fitzsimmons, from Queen's University Belfast's Astrophysics Research Centre, has been providing research support to the mission team.

He said Philae's reconnection was "wonderful" for European astronomy.

"This is really telling us something about how our solar system formed," Prof Fitzsimmons told BBC Radio Ulster.

'Groundbreaking'

The European Space Agency's Philae project was hailed as one the most audacious space missions ever undertaken, as it involved landing a spacecraft about the size of a fridge on a moving comet.

Image copyright Esa
Image caption Philae landed on Comet 67P in November 2014 after a 10-year journey

At Queen's University, Prof Fitzsimmons has played a more down-to-earth role in the mission, as a member of a "groundbreaking reconnaissance and monitoring team" that has been observing comets through telescopes for years.

"Because of our expertise, we play an important role in studying the comet, both so that the spacecraft has some idea of what it was going to find when it got there and giving the global picture," he said.

Philae was dropped by its mother ship Rosetta and landed on Comet 67P on 12 November last year.

Prof Fitzsimmons said: "Unfortunately, it bounced a couple of times where it landed."

'Deep sleep'

He said that when it came to a stop, it was "very poorly situated" in relation to its position to the sun.

"It had a battery that lasted about 60 hours but once that ran out there wasn't enough light falling on its solar cells for it to continue operating, so it went into, if you like, deep sleep."

But he added that the comet itself had now moved closer to the sun, meaning both Philae and its mother ship, Rosetta, which is still flying alongside the comet, have been able to re-establish a connection.

"Rosetta has been beaming commands every couple of weeks to Philae, in the hope that it will signal back, and now it has," Prof Fitzsimmons said.

"Philae is basically saying 'Hello, I'm awake, I'm going to check myself out and then we can back to doing some science'."

The astronomer said the fact that the lander had been "shielded from the sun" for months may have actually protected its instruments from exposure.

He said it would be exposed to temperatures of up to 100C during the day and -200C at night which would put "incredible stress" on its equipment.

Prof Fitzsimmons said it was "amazing" that it has survived and it still operating. He said he was "so happy" for all his colleagues involved in the mission.

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