Phobos-Grunt Options

[tolis]

The plot thickens..apparently there is a statement made at the bottom of page 1 of the same report:

www.russianspaceweb.com/phobos_grunt.html

to the effect that the presently baselined LV (ie the Zenit) *can* send P-G+Y-H to Mars in 2011!

[mps]

Maybe the Zenit was considered powerful enough at the time, but the s/c maxed out its mass budget?

[tolis]

That is quite likely. The majority of flight projects have a tendency to gain mass with time.
How much the actual flight model ends up weighing depends on a particular project's mass "discipline".

[Paolo]

Anatoly Zak has an update on F-G, it seems like the soil sampler would not work and its replacement with a drill was one of the reasons that caused the delay to 2011
http://www.russianspaceweb.com/phobos_grun...flight.html#gzu
this is funny because he has previously reported that the drill was discarded as it would not work in the weak gravity of Phobos...

[Hungry4info]

Have they found a way around that? Maybe a mechanism to push it into the soil?

[Gsnorgathon]

They'd pretty much have to harpoon Phobos in order to do that, wouldn't they? Or fire thrusters to hold the spacecraft against the surface. Otherwise, pushing the drill into the surface would just push the lander up.

[Explorer1]

Rosetta's lander Philae has just that; a harpoon to stick it to the surface of the comet. Whether such a thing would work on rock instead of ice remains to be seen, if Phobos-Grunt is even using that method.

[Paolo]

A short release in Russian on the site of the space agency Roskosmos
http://www.roscosmos.ru/main.php?id=2&nid=9603
In it, the new sampler is described as a "penetrator" and "a sort of pneumatic drill".I suspect it to be something resembling Beagle 2's "mole"

[Paolo]

Poland will apparently have a penetrator on Fobos-Grunt
http://press.cbk.waw.pl/10/cbk10040801/
I am not able to read Polish, but I have seen reports that it will be used to collect samples, which seems a bit strange to me...

[centsworth_II]

Poland will apparently have a penetrator on Fobos-Grunt...

From this Google translation, it looks to me like this is a sort of remote sample collector that will not transmit reaction forces from its activity to the spacecraft and force it from the surface. I don't know how the penetrator works without forcing its own self from the surface. Google calls the penetrator a "hamster". I suppose that after the sample is collected, the "hamster" is retracted by a tether to the sample container.

"The key objectives of the mission should be to provide material samples to Earth from the surface of Phobos, satellite of Mars. The material will be downloaded through the Polish penetrator and placed in a container and the inside of Russian capsule....

....in the case of a device used for driving [into] the ground, [low gravity] becomes a serious obstacle.... the reaction....would result in rejection of the lander from the surface. Due to unique design, the Polish penetrator can hammer on [its] own....if the surface has proved to be too hard for other manipulators, designed for loose soil... [the] Penetrator will serve as the testing of thermal and thermal conductivity of the surface of Phobos."

[Phil Stooke]

Paolo, check your own post just above! It's a mole, not a hamster. It's not the kind of penetrator you drop from orbit, but it can still collect subsurface samples. The Beagle 2 analogy is a good one.

Phil

[centsworth_II]

Paolo, check your own post just above!

The Yahoo Babelfish translation of the article linked in that post calls the penetrator a "pick hammer". I wonder if that is a realistic description of its mode of operation:

"...new manipulator is the pick hammer, which makes it possible to separate the part of ground and to move [it] into the receiving device."

[Paolo]

A rough translation from a Polish contact of mine:

Polish Space Research Center in Warsaw started it's work on geological penetrator called CHOMIK, that will be used on Russian mission Phobos-Grunt. In few years time the sample of Phobos collected by penetrator will land back on Earth.

Main goal of the mission is to return sample of Phobos material from it's surface. Material will be collected by polish penetrator and then placed in special container which will be installed inside Russian return capsule. The capsule itself is supposed to land in 2014, Kazakhstan.

The agreement with Space Research Institute of Russian Academy of Sciences and Lavochkin was signed on April 2nd. Polish scientists will gain rights to send their representatives into team that will study the material taken from Phobos. Polish container for sample would be returned after extraction.

Thanks to it's unique construction Polish penetrator can dig itself in on it's own and only at the beginning of the procedure the lander mass is used to allow the sampler to go in. After fist few cycles the penetrator is anchored to the surface in a way that allows continuous operation without additional forces working on the lander.

CHOMIK guarantees successful sample taking in both soft and hard materials - too hard for other designs, more suited for loose material.

Penetrator will also be used for scientific data gathering - especially thermal studies of the ground.

[rlorenz]

Poland will apparently have a penetrator on Fobos-Grunt
http://press.cbk.waw.pl/10/cbk10040801/
I am not able to read Polish, but I have seen reports that it will be used to collect samples, which seems a bit strange to me...

The Polish Space Research Center has developed a self-hammering drill (similar sort of principle to
the Beagle 2 mole) that is, used on the Rosetta lander Philae to insert a thermal properties
probe into the cometary surface. Here's a picture (inverted, the tall slender part is the thermal
probe, the hammer part is at the bottom) I took at the 2nd International Workshop on Penetrometry
in the Solar System in Graz, Austria in 2006 (IIRC the drill was demonstrated at the workshop)

Note that this system is quite separate from the
pyro-launched barbed anchoring harpoons that hold Philae down.

From the description I could readily believe that an adaptation of this device is being flown on P-G.

Attached thumbnail(s)

 

[Paolo]

According to the IKI report, Italian participation also is in doubt, due to financing problems from our space agency

resuscitating this old post, the latest F-G payload in http://sci.esa.int/science-e/www/object/do...fobjectid=46877 does not include any Italian instrument. Too bad!