American Space Preeminence: Fwd: Philae completes main mission before hibernation

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: November 15, 2014 9:58:47 AM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: Philae completes main mission before hibernation

Pioneering Philae completes main mission before hibernation

Philae's first touchdown seen by Rosetta's NavCam
15 November 2014
Rosetta's lander has completed its primary science mission after nearly 57 hours on Comet 67P/Churyumov–Gerasimenko.
After being out of communication visibility with the lander since 09:58 GMT / 10:58 CET on Friday, Rosetta regained contact with Philae at 22:19 GMT /23:19 CET last night. The signal was initially intermittent, but quickly stabilised and remained very good until 00:36 GMT / 01:36 CET this morning.
In that time, the lander returned all of its housekeeping data, as well as science data from the targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT. This completed the measurements planned for the final block of experiments on the surface.
First comet panoramic
In addition, the lander's body was lifted by about 4 cm and rotated about 35° in an attempt to receive more solar energy. But as the last science data fed back to Earth, Philae's power rapidly depleted.
"It has been a huge success, the whole team is delighted," said Stephan Ulamec, lander manager at the DLR German Aerospace Agency, who monitored Philae's progress from ESA's Space Operations Centre in Darmstadt, Germany, this week.
"Despite the unplanned series of three touchdowns, all of our instruments could be operated and now it's time to see what we've got."
Against the odds – with no downwards thruster and with the automated harpoon system not having worked – Philae bounced twice after its first touchdown on the comet, coming to rest in the shadow of a cliff on Wednesday 12 November at 17:32 GMT (comet time – it takes over 28 minutes for the signal to reach Earth, via Rosetta).
Philae's instruments
The search for Philae's final landing site continues, with high-resolution images from the orbiter being closely scrutinised. Meanwhile, the lander has returned unprecedented images of its surroundings.
While descent images show that the surface of the comet is covered by dust and debris ranging from millimetre to metre sizes, panoramic images show layered walls of harder-looking material. The science teams are now studying their data to see if they have sampled any of this material with Philae's drill
"We still hope that at a later stage of the mission, perhaps when we are nearer to the Sun, that we might have enough solar illumination to wake up the lander and re-establish communication, " added Stephan.
From now on, no contact will be possible unless sufficient sunlight falls on the solar panels to generate enough power to wake it up. The possibility that this may happen later in the mission was boosted when mission controllers sent commands to rotate the lander's main body with its fixed solar panels. This should have exposed more panel area to sunlight.
Rosetta's trajectory after 12 November
The next possible communication slot begins on 15 November at about 10:00 GMT / 11:00 CET. The orbiter will listen for a signal, and will continue doing so each time its orbit brings it into line-of-sight visibility with Philae. However, given the low recharge current coming from the solar panels at this time, it is unlikely that contact will be re-established with the lander in the near future.
Meanwhile, the Rosetta orbiter has been moving back into a 30 km orbit around the comet.
It will return to a 20 km orbit on 6 December and continue its mission to study the body in great detail as the comet becomes more active, en route to its closest encounter with the Sun on 13 August next year.
Over the coming months, Rosetta will start to fly in more distant 'unbound' orbits, while performing a series of daring flybys past the comet, some within just 8 km of its centre.
Data collected by the orbiter will allow scientists to watch the short- and long-term changes that take place on the comet, helping to answer some of the biggest and most important questions regarding the history of our Solar System. How did it form and evolve? How do comets work? What role did comets play in the evolution of the planets, of water on the Earth, and perhaps even of life on our home world.
"The data collected by Philae and Rosetta is set to make this mission a game-changer in cometary science," says Matt Taylor, ESA's Rosetta project scientist.
Fred Jansen, ESA's Rosetta mission manager, says, "At the end of this amazing rollercoaster week, we look back on a successful first-ever soft-landing on a comet. This was a truly historic moment for ESA and its partners. We now look forward to many more months of exciting Rosetta science and possibly a return of Philae from hibernation at some point in time."

More about Rosetta
Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.

Copyright 2000 - 2014 © European Space Agency. All rights reserved.

Philae comet lander loses power, drops off line
11/14/2014 08:36 PM

Editor's note...
Posted at 11:40 AM ET, 11/14/14: Comet lander's batteries near exhaustion
Updated at 06:30 PM ET, 11/14/14: Philae phones home as batteries near depletion; attempts turn in place to improve solar power
Updated at 08:10 PM ET, 11/14/14: Loss of contact; Philae presumably runs out of power
By WILLIAM HARWOOD
CBS News

Trapped in a forbidding jumble of sun-blocking cliffs and rocky debris, the Philae comet lander, its batteries nearly depleted, somehow managed to contact the Rosetta mothership Friday in true cliffhanger fashion, relaying stored science data back to Earth and receiving commands to turn in place in a last-ditch bid to bring a larger set of solar cells into the meager sunlight.

But a few moments after the pirouette, battery voltage suddenly plummeted and engineers said the end was near. Trapped between a rock and a dark place beyond its ability to survive, Philae dutifully sent back stored data and even made fresh measurements until finally, just after 7:30 p.m. (EST-5), contact was finally lost.

"Link is intermittent," the European Space Agency tweeted. A few moments later: "The @Philae2014 Lander has switched to stand by due to low power. All instruments off." ESA followed with a tweet saying the lander was "now sending only housekeeping data at very low rate. All instruments are off."
Flight controllers at the European Space Operations Center in Darmstadt, Germany, anxiously study telemetry from the Philae comet lander during a final communications session Friday. Contact was lost a few minutes later as the lander's battery was depleted. (Credit: ESA)

Stephan Ulemac, the Philae lander operations manager, said he was thrilled with the spacecraft's performance. As Philae entered "idle mode," sending the occasional data packet and final bits of housekeeping telemetry, Ulemac marveled "we can even watch it falling asleep."

A few minutes later, ESA tweeted: "Loss of signal. No more comm with @Philae2014. All science data from First Science Sequence successfully downloaded."

It was not immediately clear whether contact was lost because Philae's battery power dropped below the 21.5 volts needed for normal operation or because Rosetta passed out of view in its orbit around Comet 67P/Churyumov-Gerasimenko.

Either way, stranded in the cold shade of comet cliffs more than 310 million miles from Earth, the 220-pound Philae presumably began slipping into the equivalent of an electronic coma as its battery power steadily draining away.

"Congratulations to the amazing work by the Rosetta/Philae/ESA team," @BadAstronomer tweeted. "You had an entire planet cheering on a small robot 500 million km away."

More than any space mission in recent memory, Rosetta's encounter with 67P/Churyumov-Gerasimenko and Philae's wild, bouncing touchdown have played out in public on the internet with Twitter capturing the thoughts of many during the lander's apparently final moments.

"Now Philae down to sleep,
"We pray a sunbeam soon to sweep
"And if the hibernation break
"We have more science yet to make," tweeted @BadPhysics.

"...this is why we feel emotions for little @Philae2014 -- it may be nuts, bolts, aluminum and circuits, but it represents us. And science," wrote @astroengine.

"Sleep well, @Philae2014! Thank you for the images and data. Come back to us when panels are warmed up (hopefully soon!)," said @spacewriter.

Tweeted @BBCPallab: "This death scene by #Philae2014 is almost Shakespearean."

But reports of Philae's demise may be premature. While engineers were not particularly optimistic, the lander's final maneuver should have brought a larger set of solar cells into the limited light of the sun. It might possibly be just enough to revive the hardy spacecraft when Comet 67P/Churyumov-Gerasimenko moves closer to the sun next year and the light falling on the solar cells intensifies.

"So there is some hope that at some stage when we're closer to the sun that Philae wakes up again and talks to us," Ulemac said earlier. "But we need to be very lucky that this happens."

Regardless of the long-term outlook, engineers at the European Space Operations Center were clearly thrilled the lander managed to send home a final set of science data, possibly including the results of an attempt to drill into the crust of the nucleus to collect pristine material for analysis.

Asked how he felt about the mission, Ulemac said he was "satisfied, I have to say."

"Of course, it's a little bit sad to see the power voltage curve going down," he said. "But I'm very happy. ... We lived longer than we could expect in the conditions we had."

He said the science teams had a wealth of data to study from the observations Philae was able to complete and "they should be really happy" with "a lot of data. From what I've seen, it looks pretty good."

Philae's wild ride began early Wednesday when Rosetta released it for a seven-hour descent to the surface of 67P/Churyumov-Gerasimenko. The lander was equipped with harpoons and ice screws to anchor itself to the nucleus at the moment of touchdown, but the systems failed to operate and Philae bounced back up into space, reaching an altitude of more than 3,000 feet before coming back down again two hours later.

The lander then bounced away again, finally coming to rest more than half a mile from its original touchdown point. Or so the telemetry indicates. Engineers do not yet know precisely where the spacecraft ended up, whether the initial two-hour bounce was mostly vertical and how that played in with the comet's 12.4-hour rotation.

Wherever it ended up, frames from a panorama taken after it came to rest revealed nearby cliffs and a chaotic jumble of dark rock-like debris casting long shadows and allowing only minimal sunlight to reach Philae's solar cells.

"We are not toppled over," Valentina Lommatsch said from the lander control center. "It looks like we're kind of surrounded by rocks. ... But pictures show all three legs on the ground, and I can confirm from the solar data we have not moved at all since the first set of panorama images after the third landing. So we are on the ground, we just have really (been) unlucky in a corner surrounded by rocks."

Philae was launched with 50 to 60 hours of charge in its primary and secondary batteries. By Friday morning, most of that was depleted.

In the lander's original orientation sunlight reached the solar panels during a roughly 90-minute period each 12.4-hour "day." For most of that time, less than 1 watt is available, but power output climbs to 3 or 4 watts for about 20 minutes.

"The lander needs 5.1 watts to boot, so we have to at least get that," Lommatsch said. "After we have that, in order to charge the batteries we have to heat it up to zero degrees Celsius. In the simulations that we've run, that would mean that we'd need about 50 to 60 watt-hours a day in order to reach zero degrees and still have some of the daylight left to charge the battery. So it doesn't look that great."

But Lommatsch said as 67P/Churyumov-Gerasimenko moves closer to the sun and warms up, the amount of sunlight hitting the spacecraft will intensify enough to possibly rouse the lander from its slumber.

But it would take a considerable amount of luck. Rosetta would need go be within line of sight and the lander would need enough power to drive is computer and radio gear.

"Having a link would need additional power again, so we'd have to have something in the battery in order to have a link or be extremely lucky that Rosetta is looking for us in the moment that sunlight reaches the solar panels," Lommatsch said.

While "it looks a bit bad," she said, "we can only hope that as we approach the sun, maybe in August if we don't have too much dust or a huge coma blocking the sun, perhaps there would be a chance that at some point we could come back and at least see how the lander's doing. "So cross your fingers, or press your thumbs if you're German, perhaps we'll hear something from the lander again."

© 2014 William Harwood/CBS News

Philae Idled – Needs Luck, Sunshine to Awake
by Bob King on November 15, 2014

The animated image below provides strong evidence that Philae touched down for the first time almost precisely where intended. The animation comprises images recorded by Rosetta's navigation camera as the orbiter flew over the (intended) Philae landing site on November 12th. The dark area is probably dust raised by the craft on touchdown. The boulder to the right of the circle is seen in detail in the photo below. Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
Contact with the Philae lander was lost at 6:36 p.m. (CST) this evening November 14th before the normal loss of signal when Rosetta orbits below the lander's horizon. Without sunlight to juice up its solar panels and recharge the its batteries, the craft will remain in "idle mode" – maybe for a long time. All its instruments and most systems on board have been shut down.
"Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence," says DLR's Stephan Ulamec, Lander manager. All of the science instruments were deployed, including the instruments that required mechanical movement, such as APXS, MUPUS, and the drill, which is designed to deliver samples to the PTOLEMY and COSAC instruments inside the lander.
This image was taken by Philae's down-looking descent ROLIS imager when it was about 131 feet (40 meters) above the surface of the comet. The surface is covered by dust and debris ranging from millimeter to meter sizes. The large block in the top right corner is 16.4 feet (5 m) in size. In the same corner the structure of the Philae landing gear is visible. Credit: ESA/Rosetta/Philae/ROLIS/DLR
No contact will be possible unless maneuvers by controllers on the ground nudge Philae back into a sunnier spot. On its third and final landing, it unfortunately came to rest in the shadow of one of the comet's many cliffs.
Jagged cliffs and prominent boulders are visible in this color image taken by OSIRIS, the Rosetta spacecraft's scientific imaging system, on September 5, 2014 from a distance of 38.5 miles (62 km). Credit: ESA/Rosetta/MPS for OSIRIS team
This evening, mission controllers sent commands to rotate the lander's main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight, but we won't know until Saturday morning (Nov. 15) at 4 a.m. (CST) when the Rosetta orbiter has another opportunity to listen for Philae's signal.
Our last panorama from Philae? This image was taken with the CIVA camera; at center Philae has been added to show its orientation on the surface. Credit: ESA
The batteries were designed to power the probe for about 55 hours. Had Philae landed upright in the targeted region, its solar panels would have been out in the open and soaking up the sunlight needed for multiple recharges. There's also the possibility that months from now, as seasons progress and illumination changes on the comet, that the Sun will rise again over the probe.
We may hear from the lander again or not. But if not, all the science instruments were deployed in the first two days of landing and data has been received.
* Update 7 a.m. (CST) November 15: A bit of good news! Rosetta has regained contact with Philae during the overnight communication pass, confirming that the lander still has power. The bad news is that the batteries will be completely drained sometime today.
Deputy flight director Elsa Montagnon watches data flow from Philae on the surface of comet 67P/C-G Credit: ESA
Science data transmitted by Philae on November 14th. Credit: ESA