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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

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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

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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:

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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

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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

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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

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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

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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

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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

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Influence of the Surface Roughness

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Comparison Heater Temperatures – Duty Cycle

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Thermal Model of the Heater

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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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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

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Development schedule of Prototype 2 M

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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)

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