Rosetta, Philae and Comet 67P/Churyumov-Gerasimenko.

[eRe4s3r]

Bandwidth isn't exactly great at those distances. Particularly when every other mission beyond lunar orbit is dependent on the same facilities.

Bandwidth isn't just "not great", it's a mere 26kb/s for science/image and 2kb/s for house-keeping (Lander to Rosetta). Rosetta itself has a much bigger uplink and downlink. The problem with scientists is always that I have no idea whether they mean bytes or bits... does anyone know that?

I still have a question, because the wording is weird, did the drill touch ground and did the sample result from the 2 science instruments that are connected to it send data ? Ie, did they get the data for all experiments except APXS ?

[Funeh]

It'll be a long while, if ever. The batteries simply won't charge if they're too cold, and they won't be significantly heated until the comet's much closer to perihelion.

Are we talking days? weeks? Or months?

[Streetwind]

Well, and thus ends the primary mission... shame about APXS, and the various landing systems, but that just goes to show how much of an impact ten years in cold vacuum can have on delicate equipment. I do think the scientists managed to get everything they could out of Philae, and I'm pleased that they were able to analyze a surface sample and perform three CONSERT passes. Those two were the most important experiments in my opinion.

Let's hope the square-cube-law works in our favor and Philae gets to wake up again sometime in the future

Are we talking days? weeks? Or months?

Months... probably.

[Camacha]

Well, nobody expected the mission to fail in just this way. Reasonably, one could have expected that a failed landing amounts to a failed mission. That it bounced but caught a snag is incredibly good luck. Wondering about RTGs is hindsighting in it's purest form. Coming to think of it, why didn't they equip the probe with a beacon? If it could blink a flashlight, they'd have no trouble determining it's position, and could decide whether a hop would be worthwhile.

I feel we have been following different missions. The whole affair, from selecting a landing site to getting all the data out, has been dictated by power and the lack thereof. This was a very real and relevant mode of failure. Don't forget the MER rovers were dealing with pretty much the same issues, which is why the MSL went with a RTG. We had a beautiful, successful and amazing Philea mission, but that changes little about the circumstances.

It is a little too easy to call it hind sighting, because its not. Judging by the reaction from the people involved when asked about RTG's, they would like to use them too. It just was not an option because of logistical and political reasons, not because no one had considered them to be useful until now. Only if the latter were true it could be called hindsighting.

You don't have to take my word for it - work is underway to make Americium generators on ESA missions possible in the future. ESA is very keen to get their hands on them, and rightfully so.

[sndrtj]

CNES has compiled some pictures from CIVA: http://www.cnes.fr/web/CNES-fr/11557-gp-decryptage-du-premier-panorama-de-civa.php

[Frida Space]

Latest science update: MUPUS failed to penetrate into the ground, however it did collect some interesting data.

MUPUS TM (Thermal Mapper) worked fine throughout the whole timeline and sees a very cold steep wall in front of us. TM sees clear diurnal temperature signal. Around local noon direct sunlight on that wall caused a steep temperature increase and also steep temperature drop shortly after. Data indicate low thermal diffusivity and fluffy substance. The anchors still below Philae in shadow see the diurnal heat wave as well and at the same time as TM and the solar panels

Penetrator was deployed to the commanded distance. Remember that device had not been switched on since 2002. Temperature inside PEN dropped significantly compared to status before deployment. Might have hit a pile of stuff on the way out.

Hammering started as intended in the lowest of 3 power settings (expecting a fluffy soft surface). The depth sensor shows some up and down but no progress. The control loop increased to power setting 2. Depth sensor still shows no progress. Control loop goes to power setting 3. Still no progress! This means that the stuff is really hard! A very interesting finding, not visible from orbit! We have a secret power setting 4. Nicknamed "desperate mode". Beyond the design specs. We activated it. Still no progress. The hammer gave up and failed after 7 minutes. Jerzy was right. We were desperate, activated, were punished.

Surface must be >2 MPa hard! The comet remains surprising bizarre and uncooperative. Terrestrial analogues: Sandstone has about 5-15MPa, Granite 5-20MPa Tensile strenght

To put this into perspective: MUPUS performed beautifully inside the specifications. The comet failed to cooperate

[Camacha]

Unexpected results are the best results So much of our understanding of the world has come from a scientist going "Huh. That's funny."

Edited November 15, 2014 by Camacha

[Sky_walker]

MUPUS did some great science there. It looks like they landed on a rocks with some of fluffy powder. There was a lot of debate in before based on Rosetta Osiris photographs if these cliffs and boulders are rocks, crust, or snow shaped over millenia into something that looks like earthy rocks. By all means it looks like these are really rocks. Another secret of the comet uncovered

If Philae would wake up in future - MUPUS will provide additional data on a temperature on a surface.

Edited November 15, 2014 by Sky_walker

[Redjoker]

Bandwidth isn't just "not great", it's a mere 26kb/s for science/image and 2kb/s for house-keeping (Lander to Rosetta). Rosetta itself has a much bigger uplink and downlink. The problem with scientists is always that I have no idea whether they mean bytes or bits... does anyone know that?

From http://www.esa.int/Our_Activities/Space_Science/Rosetta/Long-distance_communication, "During the mission, the rate at which data can be sent from Rosetta to Earth will vary from 10 to 22 000 bits per second." The usual convention is that b is bits and B is bytes.

[Technical Ben]

Could it possibly be compacted dust? That can be as strong as solid rock but more resistant to impact forces (see non-newtonian fluids for why).

[Tommygun]

Could it possibly be compacted dust? That can be as strong as solid rock but more resistant to impact forces (see non-newtonian fluids for why).

I wonder, there is something called pykrete; it is a mixture of sawdust and water ice. Pykrete has a Tensile strength of 4.826[MPa] which it higher than ice or concrete.

Could some kind of ice and dust do something similar?

http://en.wikipedia.org/wiki/Pykrete#Durability

[Camacha]

I wonder, there is something called pykrete; it is a mixture of sawdust and water ice. Pykrete has a Tensile strength of 4.826[MPa] which it higher than ice or concrete.

Could some kind of ice and dust do something similar?

That is not a bad suggestion at all, composites can have strange qualities.

[lajoswinkler]

I wonder, there is something called pykrete; it is a mixture of sawdust and water ice. Pykrete has a Tensile strength of 4.826[MPa] which it higher than ice or concrete.

Could some kind of ice and dust do something similar?

http://en.wikipedia.org/wiki/Pykrete#Durability

Of course. That's the probable explanation. 2 MPa is not a lot for icy-rocky composite. The hardness probably varies a lot on the surface. We only have one data point so we can't make a generalization.

[GregA]

This picture is particularly fascinating. It looks like some sort of gravel substance, held together by a clay like sub-strait. We know these pictures are extremely high contrast so that material is almost solid black.

If this data holds out, this could be one of the most important pictures taken by science in the last 100 years. I mean, this picture could contain the clues to the origins of Dark Matter, and rewrite the hypothetical age of the Solar system, and even universe. Everything from how planets form, to why our solar system looks different from every other solar system (and why they all look different from each other)

Have they released any findings from the Plasma detector yet?

[Kryten]

This is almost as stupid as the electric universe stuff.

ESA is the space agency of europe, which is helpfully marked on the map. NASA is the space agency of the united states of america, which is where north america is labelled on this map. Note the seperating ocean.

[jfull]

I mean, this picture could contain the clues to the origins of Dark Matter

I'm a little confused about what this has to do with Dark Matter

Almost all theories about Dark Matter hold that its some kind of subatomic particle that has mass but doesn't interact with normal matter

[PakledHostage]

I'm a little confused about what this has to do with Dark Matter

I think GregA believes that Philae and Rosetta will find evidence to support electric universe theory, and that this will unlock secrets to such things as dark matter. Just smile and nod...

[K^2]

Almost all theories about Dark Matter hold that its some kind of subatomic particle that has mass but doesn't interact with normal matter

Not at all. "Dark Matter" merely states that majority of matter in the observable universe is non-luminous. What you are referring is the WIMP hypothesis. That drives things like search for heavy photons. Problem is, we don't have any good candidates at the moment. One of the alternatives is the MACHO hypotehsis. That just says that it's ordinary matter, but it's compact, and there is a lot of it. Comets and comet-like objects are one of the potential contributers to MACHO. The problem there is that it doesn't quite align with our modesl of star system formations and the age of the universe.

Either way, albedo of the comet has nothing to do with it. The "dark" in "Dark Matter" simply means non-luminous.

[*Aqua*]

I wonder if these 'rocks' are as hard as rocks on earth. I even wonder why they look like rocks.

The theory says comets are the left-overs of the creations of the solar system. They are just ice and dust which clumped together. Because there is almost no gravity the stuff should still be like very fine powder. How could it have this shape when it should have collapsed on every impact of new stuff and every coma phase?

In short: Why is it so rough? I expected a more smooth surface.

[Tommygun]

Well you do have what's called Space weathering from radiation, sputtering from solar wind and cosmic rays.

Also micrometeorites and maybe several passes toward the Sun over billions of years. It all takes it toll over a long time frame.

[Aningaaq]

Some questions maybe some of you could answer to me about CONSERT:

1. The frequency of the transmitter they used is 90MHz. My estimation is that this has a penetrating depth of maybe 20-30 meters depending on the permittivity of the comet material. Does that sound right?

2. Would the lander being in a strange position affect the data? Could it be corrected?

3. If they didn't know the material making up the comet...then how did they know what settings to use for the CONSERT? In my experience, not surveying with an optimal dielectric setting can give inaccurate results.

[lajoswinkler]

I wonder if these 'rocks' are as hard as rocks on earth. I even wonder why they look like rocks.

The theory says comets are the left-overs of the creations of the solar system. They are just ice and dust which clumped together. Because there is almost no gravity the stuff should still be like very fine powder. How could it have this shape when it should have collapsed on every impact of new stuff and every coma phase?

In short: Why is it so rough? I expected a more smooth surface.

Gravity plays a marginal role here. Electrical force (chemical reactions) is responsible for material hardness and properties. I am not surprised at all that at least some parts of the comet are harder than ice.

Roughness is also typical and was predicted. This is a microgravitational environment which orbital period is 6.44 years which means its orbit isn't typical of comets. It has been under mild solar particle bombardment during the whole history of solar system. Uneven composition, uneven exposure, bunch of chaotic factors made this surface.

Edited November 16, 2014 by lajoswinkler

[Tommygun]

Wow, I didn't know its orbital period was that short.

I'm surprised it has anything left to out gas at all.

[K^2]

1. The frequency of the transmitter they used is 90MHz. My estimation is that this has a penetrating depth of maybe 20-30 meters depending on the permittivity of the comet material. Does that sound right?

Depends on power of transmitter and skin depth of material. Ice at 94MHz is on the order of 1m (very rough estimate, depends a lot on composition). In other words, you'd be losing a factor of e for every meter. Transmitter on Rosetta is 2W. So at 20m, you'll be expecting ~4nW of power, which seems like too weak of a signal to detect. But if I'm underestimating resistivity (~50 ohm-meters) or simply making mistakes on composition (likely), this could be way off. Cometary nuclei tend to be on the order of .4g/cm³, which would point to large gaps or pores in ice. That could easily more than double the skin depth alone. All in all, I wouldn't be surprised if we're actually looking at something approaching mW ranges, which is easily detectable.

But yeah, composition is going to make a huge difference.

2. Would the lander being in a strange position affect the data? Could it be corrected?

Certainly will. Antenna had to be a specific distance from surface for experiment to work correctly. How much of it they'll be able to salvage depends on how precisely they can determine orientation of the lander. Last I've heard, they aren't sure which end is up. maybe that changed.

3. If they didn't know the material making up the comet...then how did they know what settings to use for the CONSERT? In my experience, not surveying with an optimal dielectric setting can give inaccurate results.

They probably have a pretty good guess to start with. If it's way wrong, then their choice of pulse lengths and frequency might not be optimal. But that's pretty unlikely. Anything too unusual would have shown up in spectra.

[eRe4s3r]

From http://www.esa.int/Our_Activities/Space_Science/Rosetta/Long-distance_communication, "During the mission, the rate at which data can be sent from Rosetta to Earth will vary from 10 to 22 000 bits per second." The usual convention is that b is bits and B is bytes.

Wow.. I had seriously no idea that we are talking about 2.7kB/s at most from Rosetta to Earth... that is horribly slow O.O No wonder we never get to see such missions with live-HD feeds even though that would probably be a massive help to get people interested in such missions and space exploration to begin with. And I guess it would be hugely helpful to scientists too, to see the actual real-time activity of the comet, and not just snapshots in large time frames.

at 2.7kB/s it's not surprising they haven't found the lander yet. I guess they can probably take images as much as they want, but getting them downloaded and limited memory capacity is the main problem? That explains why there are so few (relatively speaking) pictures for a mission that's ongoing for 102 days (orbiting the comet, that is)

.. that actually stuns me in disbelief. Is this is purely a power usage concern? Couldn't they use direct laser communication for both things? (Would that require a dedicated new satellite?)

Ps.: And I have a hugely stupid question to add.. wouldn't a night vision camera be more useful than normal camera with variable exposure settings?

Edited November 16, 2014 by eRe4s3r