Rosetta comet chaser completes "big burn"

BarryD

"Rosetta is presently sending signals to the ground stations at about 28 Kbps; Ignacio says that the spacecraft's own telemetry downlink uses about 1 or 2 Kbps of this, so the rest is being used to download science data from Rosetta and lander science and telemetry from the surface."

Sounds like an old Telecom Eireann dial up connection!

gordongekko

BarryD wrote: »

"Rosetta is presently sending signals to the ground stations at about 28 Kbps; Ignacio says that the spacecraft's own telemetry downlink uses about 1 or 2 Kbps of this, so the rest is being used to download science data from Rosetta and lander science and telemetry from the surface."

Sounds like an old Telecom Eireann dial up connection!

More like current eircom connections :-)

animaal

Given that this was all designed so long ago, I hope the designers provided sufficient floppy disks for the craft to store data while waiting on the slow modem...

Iranoutofideas

Just send up an eircom engineer with a flask of tay,some hang sandwiches and a roll of double sided sticky tape. Any problems sorted in a jiffy.

Nermal

It's basically definitely on it's side right? I can't interpret the picture any other way. Unless it's inside a cave or something.

Alun

It's not just the fact that the technology is "old", but also that computer hardware for use in space applications in general is specced very conservatively. You can't use hardware that uses too small a feature size as they then become more susceptible to cosmic rays, you also have to balance power usage and the resulting heat generation against clock frequency, often running chips well below their normal specs. You also don't want to be using bleeding edge technology, preferring more technology from a previous generation purely for reliability reasons.

You'd be surprised though at what this "ancient" technology can achieve. On Giotto the main AOCMS (Attitude and Orbit Control Subsystem) computer ran on a RCA 1802 microprocessor underclocked IIRC to 500kHz (yes, that's kHz not MHz) and still managed to calculate it's position and attitude in real time using fairly primitive sensors that detected the sun and star constellations all the time rotating at up to 60rpm.

Generally speaking, the scientific payloads tend to be just a little more advanced in terms of the computer technology used than the main spacecraft subsystems, but not by much.

BarryD

Ah yes, Alun - realise that but just poking a bit of fun out of Eircom

Nolars

gordongekko wrote: »

More like current eircom connections :-)

No no if Eircom was in charge they would of said the ESA can receive up on 28kbps on the comet, then when they get to the comet they say due to unforeseen space conditions they can only actually receive 5 kbps.

yipeeeee

Amazing we can communicate with something 300 milllion miles away, just think about that.

Fascinating.

brevity

Some conflicting reports appearing...

From ESA:

"Philae is on the surface and doing a marvellous job, working very well and we can say we have a very happy lander," says Paolo Ferri, ESA's Head of Mission Operations at ESOC today.

During the second lander-orbiter communication slot, which ran from 06:01 UTC / 07:01 CET until 09:58 UTC / 10:58 CET this morning, "We had a perfect pass; the radio link was extremely stable and we could download everything according to the nominal plan," adds Rosetta Flight Director Andrea Accomazzo.

http://blogs.esa.int/rosetta/2014/11/13/philae-the-happy-lander/

From NewScientist:

Looks like there is more news coming out of France with a press briefing at CNES in Toulouse. According to Peter B. de Selding, a reporter for spacenews.com, Philae is a kilometre from where it first landed and is only getting 90 minutes of sunlight every 12 hours, making power conservation a priority. The solar panels may be damaged and two instruments are switched off, with only 50 to 55 hours of battery power remaining. Lucky for ESA, Philae landed from its bouncing adventures with antennas still pointing at Rosetta, otherwise they would have lost contact with the probe. But firing the harpoons again may be out of the question.

CNES: Pyrotechnical harpoon deployment system old and it may not be worth risk of use even if 1 or both not deployed, which is uncertain.

https://newscientist.creatavist.com/rosetta#chapter-132425

NeVeR

yipeeeee wrote: »

Amazing we can communicate with something 300 milllion miles away, just think about that.

Fascinating.

Ya think they are on the meteor network......




I'll get my coat !

Alun

Latest media briefing due to start at 13:00 on rosetta.esa.int !

BarryD

"We haven’t entirely located it. It’s not very close to the landing site we wanted but its not very far away. When we discussed the landing site we chose one, but we explored several sites. We are sort of on the other side of the B site. Probably."

Jean Pierre Bibring, Philae Lead Scientist

Hmm - you'd think the cameras on Rosetta itself might be able to identify it?? Presumably otherwise they can do some form of trilateration using the radio signals to plot it's position?? Presumably they know the location of Rosetta fairly accurately.

Javan

BarryD wrote: »

"We haven’t entirely located it. It’s not very close to the landing site we wanted but its not very far away. When we discussed the landing site we chose one, but we explored several sites. We are sort of on the other side of the B site. Probably."

Jean Pierre Bibring, Philae Lead Scientist

Hmm - you'd think the cameras on Rosetta itself might be able to identify it?? Presumably otherwise they can do some form of trilateration using the radio signals to plot it's position?? Presumably they know the location of Rosetta fairly accurately.

The Rosetta camera is not able to resolve something as small as the lander from the orbital height.
The images taken from 10km have a resolution of about 83cm per pixel. At that resolution the lander would be about a single pixel.
The current orbit is higher than 10 km, so the lander would be smaller than a single pixel.


.. of course I could be wrong! that Osiris scientist seemed confident of actually imaging the lander from the orbiter.

Nolars

https://twitter.com/Philae2014/status/532892983755309056/photo/1

shedweller

Nolars wrote: »

https://twitter.com/Philae2014/status/532892983755309056/photo/1

Taken 40m from the surface. Was that on the way down or up, i wonder??

josip

shedweller wrote: »

Taken 40m from the surface. Was that on the way down or up, i wonder??

I would guess on the way down given that the surface doesn't look disturbed.
Pity it didn't stick there, looks like a nice spot.

josip

So the Philae positives

• The camera works
• It has comms to Rosetta
• The batteries are working

The negatives

• Of the 3 different mechanisms for securing it to the comet none of them worked/were effective
• Its orientation on the comet is unknown, it could be on its side since only 2 legs are in contact with the surface of the comet
• It could have as little as 30 hours of battery life left
• Its not getting enough light to recharge its batteries

These are the instruments on board.

APXS The Alpha Particle X-ray Spectrometer detects alpha particles and X-rays, which provide information on the elemental composition of the comet's surface. The instrument is an improved version of the APXS of the Mars Pathfinder.
COSAC The COmetary SAmpling and Composition instrument is a combined gas chromatograph and time-of-flight mass spectrometer to perform analysis of soil samples and determine the content of volatile components.
Ptolemy An instrument measuring stable isotope ratios of key volatiles on the comet's nucleus.
ÇIVA The Comet Nucleus Infrared and Visible Analyzer is a group of six identical micro-cameras that take panoramic pictures of the surface. Each camera has a 1024×1024 pixel CCD detector. A spectrometer studies the composition, texture and albedo (reflectivity) of samples collected from the surface.
ROLIS The Rosetta Lander Imaging System is a CCD camera that will obtain high-resolution images during descent and stereo panoramic images of areas sampled by other instruments. The CCD detector consists of 1024×1024 pixels.
CONSERT The COmet Nucleus Sounding Experiment by Radiowave Transmission experiment will use electromagnetic wave propagation to determine the comet's internal structure. A radar on Rosetta will transmit a signal through the nucleus to be received by a detector on Philae.
MUPUS The MUlti-PUrpose Sensors for Surface and Sub-Surface Science instrument will measure the density, thermal and mechanical properties of the comet's surface.
ROMAP The Rosetta Lander Magnetometer and Plasma Monitor is a magnetometer and plasma sensor to study the nucleus' magnetic field and its interactions with the solar wind.
SESAME The Surface Electric Sounding and Acoustic Monitoring Experiments will use three instruments to measure properties of the comet's outer layers. The Cometary Acoustic Sounding Surface Experiment (CASSE) measures the way in which sound travels through the surface. The Permittivity Probe (PP) investigates its electrical characteristics, and the Dust Impact Monitor (DIM) measures dust falling back to the surface
SD2 The Drill, Sample, and Distribution subsystem obtains soil samples from the comet at depths of 0 to 230 millimetres (0.0 to 9.1 in) and distributes them to the Ptolemy, COSAC, and ÇIVA subsystems for analyses.

If we exclude any instrument that would be inoperable if the lander is on its side that just leaves ROLIS, CONSERT, MUPUS and ROMAP as instruments that could still work from my very basic analysis of the lander design.

2 components of the lander have worked (ROLIS and Radio Comms) and 2 have not worked (Thruster and Harpoon firing) so from that I'm extrapolating, very tenuously, a 50% failure rate of instrumentation. Which after 10 years of cosmic rays wouldn't be bad.

So 2 of the 4 instruments would be expected to work.
And one of those is the already working ROLIS, so that just leaves one other of CONSERT, MUPUS and ROMAP.

Too pesimistic?
Or too optimistic?

Javan

josip wrote: »

So the Philae positives

• The camera works
• It has comms to Rosetta
• The batteries are working

The negatives

• Of the 3 different mechanisms for securing it to the comet none of them worked/were effective
• Its orientation on the comet is unknown, it could be on its side since only 2 legs are in contact with the surface of the comet
• It could have as little as 30 hours of battery life left
• Its not getting enough light to recharge its batteries

These are the instruments on board.



If we exclude any instrument that would be inoperable if the lander is on its side that just leaves ROLIS, CONSERT, MUPUS and ROMAP as instruments that could still work from my very basic analysis of the lander design.

2 components of the lander have worked (ROLIS and Radio Comms) and 2 have not worked (Thruster and Harpoon firing) so from that I'm extrapolating, very tenuously, a 50% failure rate of instrumentation. Which after 10 years of cosmic rays wouldn't be bad.

So 2 of the 4 instruments would be expected to work.
And one of those is the already working ROLIS, so that just leaves one other of CONSERT, MUPUS and ROMAP.

Too pesimistic?
Or too optimistic?

We know that ÇIVA, ROLIS and CONSERT are working, and I think I heard that ROMAP was working also.

The experiments that are most in doubt are those that require mechanical action. With no anchor they are understandably reluctant to start changing the balance by moving stuff about.

shedweller

If it is indeed on its side then they may just do all the science they can with what they have. There may be a chance of drilling at the end but it depends on the orientation of Philae and whats under it. It may be whats causing it to be tilted over so it may then be drillable! Last resort stuff of course.
If theres empty space under the lander then as a last resort after all experiments are done i think they should fire the harpoon if at all possible to see if they can right the lander. As i said, it's all very last resort stuff but i would certainly do it when all else is done.
Another thing, whats the story with the flywheel(s)? If there's more than one could they use them to right Philae? I'm thinking they are fixed inside so it may not be possible. But if they can tilt and move like in hubble et al then theres a chance they could right Philae that way.
Given the potential loss of solar panels and definite loss of solar gain based on where it landed, their options for any of the above are severely limited.
Exciting times though!:)

Stargate

shedweller wrote: »

If it is indeed on its side then they may just do all the science they can with what they have. There may be a chance of drilling at the end but it depends on the orientation of Philae and whats under it. It may be whats causing it to be tilted over so it may then be drillable! Last resort stuff of course.
If theres empty space under the lander then as a last resort after all experiments are done i think they should fire the harpoon if at all possible to see if they can right the lander. As i said, it's all very last resort stuff but i would certainly do it when all else is done.
Another thing, whats the story with the flywheel(s)? If there's more than one could they use them to right Philae? I'm thinking they are fixed inside so it may not be possible. But if they can tilt and move like in hubble et al then theres a chance they could right Philae that way.
Given the potential loss of solar panels and definite loss of solar gain based on where it landed, their options for any of the above are severely limited.
Exciting times though!:)

I would hope Philae can do a " Spirit and Opportunity " and surprise us all .

Come on baby we are with you ! :P

mickmackey1

shedweller wrote: »

If theres empty space under the lander then as a last resort after all experiments are done i think they should fire the harpoon if at all possible to see if they can right the lander. As i said, it's all very last resort stuff but i would certainly do it when all else is done.

They actually said there's a possibility the batteries might be re-energised when the comet's position relative to the sun changes in a few months. So they can't even be sure they're in a last resort scenario

Alun

mickmackey1 wrote: »

They actually said there's a possibility the batteries might be re-energised when the comet's position relative to the sun changes in a few months. So they can't even be sure they're in a last resort scenario

Yes, apparently when the batteries are empty it automatically goes into a deep sleep again, and when/if sufficient solar power is available, it's first used to warm up the internals of the lander and the batteries and when warmed up then starts charging. Once there's sufficient power it then springs into life again automatically.

shedweller

So its not all bad then. Yay!

brevity

I really hope it's going to be okay!

brevity

https://twitter.com/Philae_MUPUS/status/532983269261053952

expectationlost

why is it deploying the thing if its not pointing to the ground?

brevity

expectationlost wrote: »

why is it deployin the thing if its not pointing to the ground?

Maybe it's coming out of the side? Not sure really. Trying to find out more on twitter

Edit:

https://twitter.com/Philae_MUPUS/status/533004149005512704

brevity

https://twitter.com/Philae_MUPUS/status/533011127551393793

brevity

Whoever is manning the twitter account doesn't suffer fools

Keeping an eye on tweets from the @Philae_MUPUS instrument, which will try to move the lander by hammering into the comet #CometLanding

.@rcourt No that is wrong! We will deploy our thermal sensors to take the measurements MUPUS was designed to do.

brevity

https://twitter.com/Philae_MUPUS/status/533021560593219584

There's doins a transpiring

shedweller

Nailbiting! Just back from seeing Interstellar and boy am i wishing i was a spaaacemaaaan!!!

brevity

https://twitter.com/Philae_MUPUS/status/533024295443005442

Seems as though it's started some light hammering similar to this.

Rosetta Lander Philae - Mupus & Sesame First Scie…: http://youtu.be/7Hj5SG-99HE

https://twitter.com/Philae_MUPUS/status/533024553992466433

brevity

https://twitter.com/Philae_MUPUS/status/533040327058534400

shedweller

Awesome. Just awesome. Keep it up lads!

stoneill

Fox: "Why did America waste money landing on a comet?"
Scientist: "This is a European mission."
Fox: "Why didn't America get there first?"

jumbobreakfast

Philae is larger than I thought:
http://www.universetoday.com/114154/how-do-you-land-on-a-comet-very-carefully/

Mickeroo

stoneill wrote: »

Fox: "Why did America waste money landing on a comet?"
Scientist: "This is a European mission."
Fox: "Why didn't America get there first?"

Please tell me that exchange really happened

Harold Finchs Machine

Whats the fascination with twitter?

brevity

Harold Finchs Machine wrote: »

Whats the fascination with twitter?

It's a twitter account manned by a team at ESA. They give information and updates about the various instruments on Philae Lander.

shedweller

http://news.sciencemag.org/space/2014/11/end-nigh-philae-comet-lander

Looks like they are considering more risky manouvers now that the "end is nigh".
If they get the science they wanted then it will be a job well done. They did well to get this far in any case!

mickmackey1

Google hangout now

https://plus.google.com/events/c78o050l93ub7cm4kcoltjnt424

Harold Finchs Machine

Far better than a 7 word twitter.^^^

Sciencemag

brevity

https://twitter.com/RosettaSD2/status/533239124367773697

Alun

Let's just hope and pray that the power holds out long enough not just to drill and analyse the sample, but actually upload the data to Rosetta!!!

brevity

I think they will get a drip feed from when the sun hits it every so often. I heard there is still about 60 hours left in the batteries.

quad_red

Alun wrote: »

Let's just hope and pray that the power holds out long enough not just to drill and analyse the sample, but actually upload the data to Rosetta!!!

Shiraz 4.99

Why not give all these things nuclear batteries like Curiosity & Voyager ?

Alun

Shiraz 4.99 wrote: »

Why not give all these things nuclear batteries like Curiosity & Voyager ?

They talked about this on the Google Hangouts video (from about 50:15 onwards).

Basically a) there's no expertise in manufacturing these things in Europe b) launching something with plutonium in it raises serious safety concerns and c) politically it's a bit of a minefield.

brevity

Update from The Guardian

Summary

Simulations suggest battery power will last long enough for tonight’s data transmission from Philae between 21:00 and 23:00 GMT.
Esa is considering whether to spin Philae’s flywheel (designed to keep the craft upright during flight) to ‘bounce’ the lander into a new position where its solar arrays will get more sunlight to recharge its batteries.
80-90% of the intended science will have been carried out, but there’s some doubt over whether all the data will be uploaded before the lander loses all power.
All the lander’s instruments are working well. MUPUS and APXS instruments were used last night and the drill was activated. They will know this evening whether drill samples have been taken successfully. There will be more radar data to try to locate Philae.
As the comet reaches its closest approach to the sun, there may be enough power from Philae’s solar panels to wake up the lander.
84 images of the comet are being awaited from Rosetta, which will be used to try to locate the lander. There will also be descent and touchdown images relayed from Philae to Rosetta.
A manoeuvre command has been sent to Rosetta to keep the Philae landing area in sight over the coming days.

http://www.theguardian.com/science/across-the-universe/live/2014/nov/14/rosetta-mission-philaes-third-day-on-comet-as-it-happens

Sierks: Next August the comet will be “active as hell”. This is because the sun’s heat will vaporise the comet’s ices.

Cool!