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Philae phones home: Lander finally makes contact after two weeks of silence

Longest period of contact with lander confirmed
Raises hopes it could be moved into a better position

Published: 16:34 EST, 10 July 2015 | Updated: 16:38 EST, 10 July 2015

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European scientists received data from the newly revived comet lander Philae on Thursday night, a boost to the team as they try to establish a secure line of communication for their historic scientific experiments on the surface of the comet.

The European Space Agency landed Philae on comet 67P/Churyumov-Gerasimenko in November, but the lander bounced and landed in a position too shadowy to power its solar panels.

As the comet approached the sun, the lander surprised scientists by waking up and sending signals to Earth on June 13.

It is claimed that the distinct features of the comet 67P/Churyumov-Gerasimenko, such as its organic-rich black crust, are best explained by the presence of living organisms beneath an icy surface

ROSETTA: THE STORY SO FAR

The Rosetta probe, which was carrying Philae, launched into space in 2004, using the gravity of Earth and Mars to slingshot its way towards comet 67P/Churyumov-Gerasimenko.

It chased the comet through space for more than ten years, entering orbit in August 2014.

After a four-billion-mile (6.4 billion km) journey, the probe then successfully released the Philae lander (artist's impression shown left) from its grip to land on the comet on 12 November 2014, travelling at 3.3ft (one metre) a second relative to the comet.

But when it first made contact with the surface it failed to fire harpoons that would have kept it attached to the comet.

This resulted in it bouncing twice above the comet before landing.

Philae managed to perform more than 90 per cent of its goals on the surface before running out of power. Rosetta, meanwhile, continued to orbit and study the comet.

From data collected by the two probes, Esa said that water on the comet was different to that on Earth - suggesting water on our world came from an asteroid, not a comet.

Now, after a wait of seven months, enough sunlight is reaching Philae's solar panels that it has been able to communicate again.

It will now turn on some of its instruments again to perform new science. Whether there is any ice in the cliff it is wedged under, though, is unknown.

However, since then scientists have struggled to restore a secure data link between Philae and the orbiting Rosetta mothership. The secure link is needed for the scientists to relay commands to Philae's instruments and receive data back from the surface of the comet.

Philae radioed Rosetta for 12 minutes on Thursday evening, and was able to transmit data from one of its instruments, CONSERT, which is probing the internal structure of the comet, the DLR German Aerospace Centre said on Friday.

The team, which had not received communication from Philae since June 24, had attempted to turn on the CONSERT instrument on July 5 but were not sure if the command had been picked up.

'This sign of life from Philae proves to us that at least one of the lander's communication units remains operational and receives our commands,' said Koen Geurts, a member of the lander control team at the DLR in Cologne.

However, the team is still unsure as to why Philae managed to communicate on Thursday but not before, the statement said.

'The new information will help us understand why we're having these difficulties communicating with Philae,' Geurts said.

Recently the comet hit the headlines when it was claimed comet lander Philae may be sitting on an object teeming with alien microbial life, according to two leading astronomers.

Thursday's eighth contact was the longest yet, with an uninterrupted stretch of 12 minutes, said the CNES, which allowed the downloading of critical data obtained from Philae's prodding and probing of its alien world.

'The link was by far the best yet, with very few interruptions,' said the statement.

'It bodes well for the future because such a good connection would allow the teams to take control of Philae and give it commands'—possibly to shift position or start its drill for a sub-surface examination.

Distinct features of the comet 67P/Churyumov-Gerasimenko, such as its organic-rich black crust, are best explained by the presence of living organisms beneath an icy surface, they claim.

The experts go as far as to suggest the comet is more hospitable to life than the Earth's polar regions.

Rosetta, the European space craft orbiting the comet, is also said to have detected strange 'clusters' of organic material that look suspiciously like viral particles.

But neither Rosetta nor its lander are equipped to search for direct evidence of life after a proposal to include this in the mission was allegedly laughed out of court.

Steep ravines, icy surfaces and a thick dusty veil are captured on the comet's surface in high-resolution photographs taken by the Rosetta spacecraft

Astronomer and astrobiologist Professor Chandra Wickramasinghe, who was involved in the mission planning 15 years ago, said: 'I wanted to include a very inexpensive life-detection experiment. At the time it was thought this was a bizarre proposition.'

He and colleague Dr Max Wallis, from the University of Cardiff, believe 67P and other comets like it could provide homes for living microbes similar to the 'extremophiles' that inhabit the most inhospitable regions of the Earth.

Prof Wickramasinghe and Dr Wallis have carried out computer simulations that suggest microbes could inhabit watery regions of the comet

Comets may have helped to sow the seeds of life on Earth and possibly other planets such as Mars early in the life of the solar system, they argue.

The astronomers will present their case for life on 67P at the Royal Astronomical Society's National Astronomy Meeting in Llandudno, Wales.

Philae made history last November after detaching from its Rosetta mothership and bouncing down onto the surface of the comet, coming to rest close to a cliff or crater wall.

After being forced into hibernation by the lack of sunlight reaching its solar panels, the probe has delighted scientists by 'waking up' as the comet races towards the sun.

The comet, described as looking like a 'rubber duck', has two lobes joined by a thinner neck and measures around 2.5 miles (4km) across.

Currently it is about 176.7 million miles (284.4 million km) from Earth and travelling at more than 73,000 mph (117,482km/h).

Professor Wickramasinghe and Dr Wallis have carried out computer simulations that suggest microbes could inhabit watery regions of the comet.

Organisms containing anti-freeze salts could be active at temperatures as low as -40°C, their research shows.

The comet has a black hydrocarbon crust overlaying ice, smooth icy 'seas', and flat-bottomed craters containing 'lakes' of re-frozen water overlain with organic debris.

Professor Wickramasinghe said: 'What we're saying is that data coming from the comet seems to unequivocally, in my opinion, point to micro-organisms being involved in the formation of the icy structures, the preponderance of aromatic hydrocarbons, and the very dark surface.

The comet has a black hydrocarbon crust overlaying ice, smooth icy 'seas', and flat-bottomed craters containing 'lakes' of re-frozen water overlain with organic debris

In total, more than 70 per cent of the comet's surface has now been imaged and beamed back to earth

'These are not easily explained in terms of pre-biotic chemistry.

'The dark material is being constantly replenished as it is boiled off by heat from the sun. Something must be doing that at a fairly prolific rate.'

He said several cracks in the ice had been shown to be 'spewing out material' that is falling on to the surface.

'I think the microbiotic activity just under the surface results in gas which builds up to the point where the overlaying layers of ice can't withstand the stresses,' said the professor.

Biological mechanisms were the likely explanation for the large quantities of organic gases that had been observed around comets, along with water, he maintained.

Philae had confirmed the presence of 'ring and linear chain' organic molecules on the surface of 67P that were more complex than simple hydrocarbons such as methane, said Professor Wickramasinghe.

However it was impossible to say if these represented amino acids, the building blocks of proteins.

Moment Rosetta probe landed on moving comet (related)

One tantalising find was the discovery of organic 'particle clusters' by Rosetta in the gases surrounding the comet, which resembled viral particles collected from the Earth's upper atmosphere.

'They might be viral particles,' said Professor Wickramasinghe.

Philae will now join the comet as it makes its closest approach to the sun on 13 August 2015. After that, the comet will begin to move away back out into the solar system. It is expected that Philae will no longer have enough sunlight to continue working by about mid-October

WHAT WILL PHILAE DO NOW?

Once Philae became operational again, scientists checked to see it is healthy and turned its instruments on.

With ten instruments on board, and only 24 Watts of power available, Philae will use its instruments one by one in a specific order that is yet to be decided.

Some of these instruments will have a chance to perform advanced science that they didn't get a chance to perform during the brief 60 hours of operation after it landed on 12 November.

Contact has been re-established with Philae. The probe's instruments (shown here) will be turned on one by one to start gathering scientific data on the surface again

For example, the Ptolemy instrument - which analyses samples from the surface - was only able to study dust last time around.

This time, the team will be hoping it can study ice on the comet.

Philae will also take images of its surroundings and send these back to Earth, so that scientists can get a better understanding of what sort of position it is in.

This will help them work out how much sunlight will fall on the probe, and how long it can stay operational for again - expected to be weeks, and possibly months, as the comet reaches its closest point to the sun on 13 August.

After this, as it gets further away, Philae will eventually run out of power and go into hibernation for a second time - this time for good.