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Rosetta space mission - Philae probe due to land on comet on 12th Nov 2014

Unfortunately Philae hasn't been heard from for some 5 days or so now. Quite possibly this is merely due to the lander-orbiter radio geometry. Mission controllers are still working to optimise the communications window and hope to hear from the lander in due course.
 
An update - early yesterday evening, after several days of very brief, or non-existent communication, Rosetta was able to download more data from Philae during a sustained 12+ minute conversation. That data is currently being analysed though initial indications are that it is responding to commands. Engineers are trying to better understand why the lander is struggling to communicate for days at a time.
 
A Philae update. No data has been received since about 9 July. Rosetta has been encountering problems with star trackers (ie navigating) due to proximity to an increasingly active nucleus so has had to back off once again (from just over 150km to 190km).

The last set of data received from Philae suggested that the lighting profile had changed between June and July (ie the illumination of the solar panels). One possibility is that Philae has shifted somewhat. This could explain the difficulty in communication as the antenna will have also moved and a different communication geometry and thus different communication windows will be needed. To complicate the issue it would appear from recent data that only one of the two transmitters on Philae are now working properly.

The current plan is to transmit 'blind' to Philae and instruct it to switch to using the good transmitter (normally it would alternate between the two transmitters for each communications session; this might also explain missed communications) and then to vary the listening windows beyond those computed for the lander position and orientation which had been assumed (previously calculated) up until now. With any luck Philae will be heard and the current status of the lander be better determined.

More details here.
 
Some of the first results from Philae have been published in the journal Science.

One of the most significant is the material sniffed by the Ptolemy and COSAC instruments.
[COSAC] indicated some 16 organic compounds comprising numerous carbon and nitrogen-rich compounds, including four compounds – methyl isocyanate, acetone, propionaldehyde and acetamide – that have never before been detected in comets. Ptolemy sampled ambient gas entering tubes at the top of the lander and detected the main components of coma gases – water vapour, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing organic compounds, including formaldehyde.

Importantly, some of these compounds detected by Ptolemy and COSAC play a key role in the prebiotic synthesis of amino acids, sugars and nucleobases: the ingredients for life. For example, formaldehyde is implicated in the formation of ribose, which ultimately features in molecules like DNA.

The existence of such complex molecules in a comet, a relic of the early Solar System, imply that chemical processes at work during that time could have played a key role in fostering the formation of prebiotic material.
Click to expand...

Much more here.

Descent to the first landing:
ESA_ROSETTA_PHILAE_ROLIS_DESCENT_1024.gif
 
Just to mention that Comet 67P reaches perihelion, the closest approach to the Sun (and more or less the peak of activity), this Thursday 13th August.
 
Perihelion was passed at 0303BST this morning. Rosetta is reported as operating fine.

To celebrate ESA have released an interactive comet viewer here, where you can explore Comet 67P/Churyumov-Gerasimenko using Rosetta imaging.

There's also an ESA hangout - Rosetta mission's day in the Sun - which is live right now with mission and science updates:
 
Some nice images were released today...

A very strong and short lived (30 minutes or less) jet caught in action (12 August):


A nice sequence of images taken yesterday illustrating activity at perihelion:
ESA_Rosetta_OSIRIS_NAC_20150812_animation.gif


A large piece (current, initial estimates place it between 1 and 50 m across - more analysis is needed) of the comet breaking off and leaving the surface at escape velocity (seen 30 July):
Boulder_flying_by_comet_node_full_image_2.gif


An illustration of the dust environment around Rosetta itself on 6 July (which is why they have had to back off to over 300km - it will have gotten worse and confuses the star trackers with a vital for navigation/pointing):
Comet_s_dusty_environment_node_full_image_2.gif


Finally, now the entire comet nucleus has been sunlit (both hemispheres have experienced a 'summer' season) it has been completely mapped:
 
Not necessarily... Rosetta is concentrating on her primary mission focusing on the comet at perihelion. Attention will be turned back to Philae when nucleus activity drops off.
 
Ooooo! There's pure oxygen leaking off the comet!

cientists say they have detected significant amounts of molecular oxygen coming out of a comet, an unexpected find that may have implications for the search for alien life and understanding how the solar system formed.

Oxygen atoms are abundant throughout the universe, but because they react very easily with other elements they are rarely found in the molecular form known as O2. Scientists had previously assumed that almost all oxygen in a comet would come in the form of water (H2O), carbon monoxide (CO), or carbon dioxide (CO2).

But using instruments aboard the European spacecraft Rosetta, researchers were able to prove the existence of large amounts of O2 in the gas cloud, or coma, around the comet named 67P/Churyumov-Gerasimenko.

"It is the most surprising discovery we have made so far on 67P, because oxygen was not among the molecules expected in a cometary coma," said Kathrin Altwegg, who co-authored the study published Wednesday in the journal Nature.

Oxygen found in comet challenges solar-system theories'
Click to expand...
 
Soft crash landing of Rosetta on the comet's surface is now confirmed as the end of the mission plan.
Next September, the European Space Agency will crash Philae’s mothership Rosetta into the icy dust ball, but as gently as possible.

Rosetta’s cameras will get their best-resolution shots of the comet’s surface yet—less than 1 centimetre per pixel once the craft is within 500 metres of the surface, adds Holger Sierks, PI for Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System). This will allow researchers to look at surface properties and link these to comet activity that Rosetta has observed from orbit.

How far into the descent Rosetta will be able to send data back to mission control will depend on whether engineers can design the final trajectory such that the craft crashes on the side of the comet that faces Earth. Navigating while close to the comet will be difficult because the body’s gravitational field is uneven, but spacecraft-operations manager Sylvain Lodiot hopes that the orbiter will transmit until the very end.

The crash will definitely be a hard stop to the mission, he says, however gentle the landing. Designed to manoeuvre in orbit, once Rosetta is on the comet’s surface it will no longer be able to point its antenna to communicate with Earth. Similarly, it will not be able to angle its solar array, so it will lose power, says Lodiot. “Once we touch, hit or crash, whatever you want to call it, it’s game over.”
Click to expand...
 
There's one last, desperate chance to contact Philae coming up:

PHILAE STATUS REPORT: “TIME IS RUNNING OUT”

Rosetta’s lander Philae has remained silent since 9 July 2015. With every passing day, Comet 67P/Churyumov-Gerasimenko is getting further and further away from the Sun, and as such, temperatures are falling on the comet's surface. Things are getting critical for Philae: conditions are predicted to be “lander-hostile” – too cold – by the end of January.

But the lander team are going to try another method to trigger a reponse from Philae: on 10 January they will send a command, via Rosetta, to attempt to make Philae’s momentum wheel switch on.

"Time is running out, so we want to explore all possibilities," says Stephan Ulamec, Philae lander manager at DLR.

Philae’s momentum wheel ensured that it was stable during its descent from the orbiter on 12 November, 2014.

If the command is successfully received and executed, the hope is that it might shift the lander’s position.

"At best, the spacecraft might shake dust from its solar panels and better align itself with the Sun," explains Philae technical manager Koen Geurts at DLR’s lander control centre.

But it is also possible that the lander may not be able to respond to the command. It remains unclear as to what state Philae is in since it last sent data about its health in July, but the DLR team believes that one of the lander’s two transmitters and one of the two receivers have failed. The second transmitter and receiver apparently no longer function smoothly, either.

The team continues to hope that Philae has not tilted over or become covered with too much dust. On an active comet, which is ejecting gas and dust into space, the lander is not in a particularly safe location.

"Unfortunately, Philae's silence does not bode well," says Stephan.

In the night of 21-22 December, 2015, the receiver on Rosetta was triggered, but analysis showed that this was not a transmission from the lander.

By the end of January, 67P/Churyumov-Gerasimenko will be more than 300 million kilometres from the Sun, resulting in an operating temperature of less than -51ºC on Philae such that the lander will no longer be able to turn on.

The command to activate the spin wheel will, therefore, be one of the last attempts to obtain a response from the lander.

"There is a small chance," says Philae operations manager Cinzia Fantinati from DLR’s control team. "We want to leave no stone unturned."

The communication unit on Rosetta will still remain switched on and continue listening for Philae beyond January.

Rosetta’s mission will continue until the end of September 2016.

Philae status report: “Time is running out”
Click to expand...
 
No response was detected from Philae following the blind commanding of the flywheel spinup, however the Rosetta Osiris camera was used to image the suspected lander location at the time in case a cloud of dust could be observed. The relevant images are currently being analysed.
 
Unfortunately they have now given up any hope of further contact with Philae:
The German Aerospace Center (DLR), which led the consortium behind Philae, said the lander is probably now covered in dust and too cold to function.

"Unfortunately, the probability of Philae re-establishing contact with our team at the DLR Lander Control Center is almost zero, and we will no longer be sending any commands," said Stephan Ulamec, the lander's project manager at DLR. "It would be very surprising if we received a signal now," he said.

The Rosetta mothership may have a chance to take some final pictures of Philae in the summer, during a series of close fly-bys. Rosetta itself will end its mission when it falls onto the comet in September.
Click to expand...
Source: BBC News.
 
Goodbye Philae :(

After almost two years of extreme highs and devastating lows, the Philae lander has bid its final farewell.

At 10am BST on July 27, the Electrical Support System Processor Unit (ESS) on Rosetta was switched off. The ESS is used to communicate between Rosetta and its lander.

Philae has been silent since July 9 2015. In a series of heartbreaking tweets, the mission team (posing as the lander) wrote: "It's time for me to say goodbye. Tomorrow, the unit on @ESA_Rosetta for communication with me will be switched off forever..."
Click to expand...

Farewell Philae: Lander tweets its heartbreaking goodbyes
 
It's a shame that it has come to an end, but it was one of the most exciting expeditions in a number of years. Hopefully there'll be another comet-chaser launched at some point. :cool:
 
Possibly the grand finale is yet to come though as they end the mission by landing the orbiter on the surface of the comet's nucleus...

Current planned touchdown time is 1030UTC on 30 September (2016) near the 'neck' of the comet.
20160726_Comet_regional_maps_landing_sites_f840.jpg

The approach will be optimised to try to maintain contact for data transmission for as long as possible and with any luck we should get some very high resolution images of the surface (plus other accompanying science data). Impact speed would be about 50 cm/sec. Transmissions will cease at impact due to both change in orientation of the orbiter and the fact that it will have been commanded to shut down the transmitter at touchdown (in order to guarantee no further spurious transmissions on valuable DSN frequencies).

I said possibly earlier as, due to the extremely dusty nature of the cometary environment there is a chance that attitude control may be lost as the orbiter descends to within kilometres of the surface, in which case data and the orbiter may be lost.
 
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