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Melt
ing
Pro
be P
rog
ress M
eeti
ng
: 0
4-1
0-
20
07
Summary of the experiments done and their influence on the new design
E. Kaufmann, G. Kargl, N. Kömle
Space Research Institute of the Austrian Academy of
Sciences
ESA-Contract 19272
Progress Meeting 04.10.2007
2IWF/ÖAW GRAZ
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Melting Probe Test at Cologne
• Vacuum conditions
• Pressure: ~0.3 mbar
• Sample height: 120 cm
• Surrounding temperature:
-15°C
• Chamber cooled by LN2
• Duration of test:
47h 27 min
Experimental Set Up: Thermal Requirements:
Heating equipment
segmented in 5 regions:
•F1 Heater H1
•F2+F3 Heater H2
•F4ǁF5ǁF6 Heater H3
•F7ǁF8ǁF9 Heater H4
•F10ǁF11ǁF12 Heater H5
3IWF/ÖAW GRAZ
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Results and Conclusions from Cologne
• Approximate penetration velocity: 0.32 cm/h
• Maximum depth reached:
~15 cm
• Maximum crater diameter built around Melting Probe: ~ 11 cm
• Thermal output at the tip of the melting probe head to low.
• Collateral heat dissipation leading to a crater round the Melting Probe
• Change in design a further heating circuit closer to the front heater
Results: Conclusions:
4IWF/ÖAW GRAZ
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Melting Probe - Modifications
• Third heating segment inside the tip
• Additional external and internal temperature sensors
• no clear measurable refinement
next change in design: heaters fixed at the outer walls, directly or with the help of thin wrappings or plates
first tested with a flat front heater
5IWF/ÖAW GRAZ
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Summary of the Flat tip tests
1. Test 22.05.2007 Heaters sandwiched between brass plates
2. Test 18.07.2007 Heaters sandwiched between brass plates
3. Test 24.07.2007 Heating foil (small diameter) fixed outside by gluing
4. Test 05.09.2007 Heating foil (larger diameter) fixed outside by gluing and covered with copper foil
6IWF/ÖAW GRAZ
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Flat tip – Mechanical Design
Includes three heating circuits:
• Heater 1: between the two brass plates
• Heater 2: between second plate and cylindric part
• Heater 3: serial electrical circuit of two heating foils fixed at the inner wall of the cylindrical part
7IWF/ÖAW GRAZ
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Flat Tip- Measurement I
Penetration depth: ~21.5 cm
Penetration speed: ~1.77 cm/h
God thermal contact due to mechanical fixing for a more complex geometry this approach is not feasible new design: foils fixed directly at the front heater
Temperature increase in the E-box due to heat dissipated from the cable new design: flat cable
8IWF/ÖAW GRAZ
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Flat Tip- Measurement II
• Measurement with heating foil fixed at the outer flat surface of the front heater homogeneous heat flux within the foil not reached insufficient penetration speed
9IWF/ÖAW GRAZ
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Flat Tip- Measurement III
• Heating foil covered with copper foil heat transfer improved penetration speed of ~ 0.45 cm/h measured.
• Measurement also shows the influence of the surface roughness of the ice and the position of the electrical contacts on the attitude of the probe
10IWF/ÖAW GRAZ
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Influence of the Surface Roughness
11IWF/ÖAW GRAZ
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Comparison Heater Temperatures – Duty Cycle
13IWF/ÖAW GRAZ
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Pyramidal Tip - Heating Foils
Thermal models of two alternative designs of the front heater
Development schedule Prototype 2 M
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Melt
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Action Date Delivery time/ duration
Order tailored heater foils Now 2 - 3 months
Order remaining mechanical parts
Now 2 months
Cable extraction tests October/November 2007
2 months
Redesign electronics
(include control elements for motor driving mechanical penetration devices)
Begin now? 2 months
Assembly of cable magazine
Begin now Finished until end of year
15IWF/ÖAW GRAZ
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Development schedule of Prototype 2 M
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Melt
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Action Date Delivery time/ duration
Assemble probe for first test
February 2008
Order 10 m cable After first tests with 2 m cables
2 months
Extended test phase Begin March 2008 Several monthts
Use samples including dust
One field test to study deeper penetration
Begin summer 2008 Until end 2008
(end of project)