Subject: Rosetta Mission: MUPUS Update
From: Alex Kemp
Date: Wednesday, 19 November 2014 04:40:01 +0000
To: Oliver Kemp, Micaela Kemp, Liisa Kemp, Davin Kemp

I've finally found a site to be able to properly document that info on the MUPUS hammer breaking (link above).

  1. Sat, Nov 15 2014 18:14:45:
    Hammering started as intended in the lowest of 3 power settings (expecting a fluffy soft surface)
  2. 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
  3. 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!
  4. 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...
  5. 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:-

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