http://www.theregister.co.uk/2014/11/18/philae_lander_sniffs_out_organics_hidden_on_comet_67p/
https://twitter.com/philae_MUPUS
I've finally found a site to be able to properly document that info on the MUPUS hammer breaking (link above).
- Sat, Nov 15 2014 18:14:45:
Hammering started as intended in the lowest of 3 power settings (expecting a fluffy soft surface)
- Sat, Nov 15 2014 18:39:23:
The depth sensor shows some up and down but no progress. The control loop increased to power setting 2
- Sat, Nov 15 2014 18:39:49:
Depth sensor still shows no progress. Control loop goes to power setting 3. Still no progress!
This means that the stuff is really hard!
- Sat, Nov 15 2014 18:47:21:
We have a secret power setting 4. Nicknamed "desperate mode". Beyond the design specs. We activated it
About the 'desperate mode': the truly genius designer of the hammer, Jerzy Grygorczuk, always said "be careful with power mode 4". And...
- Sat, Nov 15 2014 18:57:01
The hammer gave up and failed after 7 minutes. Jerzy was right.
The MUPUS engineers have estimated that the surface must be >2 MPa (a measure of hardness). Here is a table of hardnesses that I've found:-
http://www.oocities.org/unforbidden_geology/rock_properties.htm
| Typical Rock Types |
Tensile Strength
(min-max, MPa) |
| Shale |
2-10 |
| Sandstone |
4-25 |
| Gneiss |
5-20 |
| Limestone |
5-25 |
| Marble |
7-20 |
| Slate |
7-20 |
| Granite |
7-25 |
| Basalt |
10-30 |
| Quartzite |
10-30 |
| Dolomite |
15-25 |
| Diorite |
15-30 |
| Gabbro |
15-30 |
| Diabase |
15-35 |
---------
Alex Kemp