17 November 2014
The amazing journey of Philae, imaged by Rosetta’s OSIRIS camera.
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Before going into hibernation at 01:36 CET on 15 November 2014, the Philae lander was able to conduct some work using power supplied by its primary battery. With its 10 instruments, the mini laboratory sniffed the atmosphere, drilled, hammered and studied Comet 67P/ Churyumov-Gerasimenko while over 500 million kilometres from Earth. After a triple landing, positioning it in a new, unplanned location, conditions were not optimal, but Philae was able to work for more than 60 hours and send the resulting data back to Earth. It was controlled and monitored from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) Lander Control Center (LCC). Now, the complicated data analysis begins. DLR's Scientific Director for the project, Ekkehard Kührt, is very pleased with the results so far. "We have collected a great deal of valuable data, which could only have been acquired through direct contact with the comet. Together with the measurements performed by the Rosetta orbiter, we are well on our way to achieving a greater understanding of comets. Their surface properties appear to be quite different than was previously thought."
The team responsible for the MUPUS (Multi-Purpose Sensors for Surface and Sub-Surface Science) instrument, which hammered a probe into the comet, estimates that Comet 67P is hard as ice: "Although the power of the hammer was gradually increased, we were not able to go deep into the surface," explains Tilman Spohn from the DLR Institute of Planetary Research, who is leading the research team. Shortly after the triple landing, the scientists could only hope that Philae would be in a position that would allow the probe to be hammered into the surface. However, with MUPUS it has been possible to directly study the strength of a comet's surface for the first time – and 67P/Churyumov-Gerasimenko proved to be a 'tough nut to crack'. "We have acquired a wealth of data, which we must now analyse," says comet researcher Spohn. Only the thermal sensors and accelerometers in the anchors that should have fixed Philae to the comet’s surface were not used, because they were not deployed during the touchdown.
Listening to the comet
The team of the SESAME experiment (Surface Electrical, Seismic and Acoustic Monitoring Experiment) can confirm that Churyumov-Gerasimenko is not nearly as soft and fluffy as it was believed to be. "The strength of the ice found under a layer of dust on the first landing site is surprisingly high," says Klaus Seidensticker from the DLR Institute of Planetary Research. The instrument CASSE, which sits in the feet of the lander, was turned on during the descent and clearly registered the first landing as Philae came into contact with the comet. From additional data, the mechanical properties of Churyumov-Gerasimenko will be derived. SESAME's two other instruments suggest that cometary activity at this landing site is low, as well as revealing the presence of a large amount of water ice under the lander.
Sniffing for organic molecules
The last of the 10 instruments on board the Philae lander to be activated was the Sampling, Drilling and Distribution (SD2) subsystem, which was designed to provide soil samples for the COSAC and PTOLEMY instruments. It is certain that the drill was activated, as were all the steps to transport the sample to the appropriate oven. COSAC also worked as planned. Now scientists need to analyse the data to determine whether a soil sample was actually examined in the gas chromatograph. This will be done in collaboration with several instrument teams. Did CASSE hear drilling? What soil strength did MUPUS encounter when hammering? With what force was the SD2 drill used? "We currently have no information on the quantity and weight of the soil sample," says Fred Goesmann from the Max Planck Institute for Solar System Research. However, COSAC was able to 'sniff' the atmosphere and detect the first organic molecules after landing. Analysis of the spectra and the identification of the molecules are continuing.
Images and radio waves before hibernation
One of the big 'winners' of the Philae landing is Stefano Mottola from the DLR Institute of Planetary Research, who is responsible for the ROLIS (ROsetta Lander Imaging System) camera. The instrument, mounted on the bottom of the lander, acquired images during the first descent showing the planned landing site, Agilkia. Even after the third landing, it proved possible to reactivate ROLIS and acquire images of the comet’s surface at close range. Thus, the team has data for two different locations on the comet.
A wealth of data was also obtained with the CONSERT (COmet Nucleus Sounding Experiment by Radio wave Transmission) instrument. To achieve this, the lander and orbiter were on different sides of the comet and worked together to analyse the comet nucleus by passing radio signals through it and creating a three-dimensional profile of the core. During the CONSERT measurements, Philae went into hibernation after the power from its primary battery was exhausted. This battery was flown through space already charged to ensure the completion of the first scientific work phase.
Waiting for news of Philae
"I'm very confident that Philae will resume contact with us and that we will be able to operate the instruments again," says DLR Lander Project Manager Stephan Ulamec. Once the rechargeable secondary battery has been warmed by sunlight again, Philae will restart and the DLR LCC team will take their places at the control consoles again. "At the first landing site, we would, of course, have had better solar illumination conditions," says Ulamec. "Now we are somewhat in shadow, we will need more time to charge." One advantage of the shadier landing site in a crater is that the Philae lander will not overheat as quickly as the comet approaches the Sun, but will benefit from the stronger sunlight. The team managed to rotate the lander during the night of 14/15 November 2014, so that the largest solar panel is now aligned towards the Sun.
Contact in the coming year
Stephan Ulamec believes it is probable that in the spring of 2015, the DLR LCC will once again communicate with Philae and receive data about how the lander is faring on Comet 67P/Churyumov-Gerasimenko. In the summer of 2015, it might be possible that temperatures on the comet will allow Philae’s battery to be recharged. "The orbiter will continue with its overflights to receive any signals from the lander once Philae wakes up from hibernation."
Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is funded by a consortium headed by DLR, the Max Planck Institute for Solar System Research (MPS), CNES and the Italian Space Agency (ASI).
Last modified:21/11/2014 13:00:10
18/11/2014 00:10 -
from Marco Guardigli
As a european citizen, I am super proud for the many successful targets achieved with this mission. As an engineer, I am amazed by the great quality of the team integration, bringing together so diverse and so equally focused experiences and contributes.As a science enthusiast, I cannot wait for the scientific treasures that this mission will add to humankind knowledge about our universe.thank you,@mgua
18/11/2014 18:50 -
from Jan Kolar
Thank you for updated overview of findings from Philae and congratulation to the historical success!Possible reason for final unwanted Philae location can be the surface of comet. The material looks to be more harder than was presumed for the anchors and leg screws construction. Unfortunately, the gas thrusters did not work either.
18/11/2014 20:17 -
Congratulation to all the different teams who have worked so hard and on such a long time period to enable this fantastic story bringing European science once again to the top of the world!
18/11/2014 22:10 -
Great job guys! This is really something to be proud of!
19/11/2014 02:37 -
from Space Judge
The title is misleading, there is no ice found at this comet.
20/11/2014 08:44 -
yep, very interesting.The technical success is absolutely the greatest thing ever, from redoing software loads and testing some 500M km away to actually land on that thing with this great shot onto a moving target.Are there by chance images taken from Rosetta after the third landing, of that right part of the crater where it could sit according to that graphic with the Bavarian rhombus.... would be nice we all could go pixel hunting and trying to find it.to the Ice: the detection of large amounts of water ice below the lander: how is this actually dotected.I am a little skeptical here. We have already that 'detection' of water around the comet: nothing when looking to the surface, or into the plumes right at the neck, and 'found water' when looking into the distant coma.....There I guess it proves that water is not outgassing from the comet, and whatever is interpreted as 'detection of water' is happening in the far away coma.So, how is that large amount of water detected? Directly, or again some indirect method that would be open to other interpretations.I see here very clearly that enormous pressure to 'prove there is water on the comet', more driven by egos of people who do desktop astrophysics and don't want their 'guess sold as science' large number of papers being ridiculed....Science has to be open minded, not ego driven.Because whatever is found here has already changed what comets are about in a big way: a rubber ducky!!!!! And it holds together somehow, Escherian gravitational fields (doing effects like in some Escher drawings with staircases in all directions), what is up here is sideways there...down there, and it did not detect the 'impact' of the dust surface itself so it seems.You know, that dust layer: built in microgravity, so the electrostatic forces between grains are the predetermining mechanical foce, not gravity: I imaging an interconnected network of chainns of electrostatically bound sub-micron dust particles could have, in microgravity, surprisingly elastic properties. Keep in mind there is no gas in the voids in the dust layer that needs to be expelled when that is compressed, so it will really stay together and might function as an elastic material with some plastic properties when chains break and reconnect.Interpreting all that in terms of what we see here on earth is really as unscientific as could be: like flat earth people...So, really, cards on the table: what was the measurement done and what is the justification to interpret it as 'large amount of water ice under the lander' in a way to trumpet it out this way.I know very well how in established science the big wigs try very hard and mean to defend their pet 'theories' (most of the time confusing a theory and a model, selling assumptions and guesses as scientific statements, because they get it published.No, I am not for replacing one unscientific ego driven 'theory' with another one (I am not talking about that 'electric universe' stuff, same bad science quality as "comets brough water to earth", or "global warming is caused by carbon dioxide" which has been found to be based on a flagrant flasification of scientific data (co2 rose after the temperature rises, not before, it follows: wildfires; or declaring co2 a 'greenhouse gas' while it is orders of magnitude less greenhousy than methane, which rises in warmings because of more termites around the equator producing more termite dung related co2).Don't join the herd of wannabe scientists who are just ego maniacs, bullies in the intellectual arena. Keep it clean and don't tout things hastily, all this is way too precious after all that technical brilliance there should be scientific brilliance too, not the same old witch hunting and person cult stuff.
20/11/2014 18:52 -
from Michel Maurette
I am puzzled by the following comment in the list of your comments:9/11/2014 02:11 - from Space JudgeThe title is misleading, there is no ice found at this comet.----------------------------------------------Do you mean no ice below the surface. Or more likely the ice is just covered by the fraction of the dust which was expelled during the last return of the comet in the inner solar system and did fall back on the comet.
22/11/2014 19:58 -
from W. P. Sokeland
I sent a report to Fred Wipple when this European comet program was started that explained a new comet model and stated that comet's do not have ice. Wipple responded by saying my model gave him a stomach ache.
23/11/2014 04:18 -
from Space Judge
Michel, I was pointing to tests and assumptions done so far at and below the comet surface. Scientists (with their instruments) probably go to find some iron and vapor not found at planet Earth, but in the Sun. Does a seed need water or can it attract water when needed...
24/11/2014 02:50 -
from Grandma Juno
I suspect that spectroscopy is the technique used to detect water. It is often used to discover what something is made of without actually touching it because every substance has a unique light signature.
26/11/2014 05:37 -
from Edward Rosen (USA)
I remain impressed and delighted by this extraordinary achievement, and continue to follow the news of the science data gained. What an audacious and triumphant program! My thanks to the many, many involved for expanding my horizons and knowledge of our Solar System and the remnants of its early development!