t

CubeSat-sized Re-entry Capsule

MIRKA2

M. Ehresmann, A. Behnke, J.-P. Baumann, R. Tietz, J. Franz,

D. Galla, B. Gäßler, F. Grabi, F. Hessinger, R. Hießl,

M. Koller, G. Kuhn, N. Müller, R. Müller,

A.Papanikolaou, J. Rieser, V. Schöneich,

H. Seiler, M. Siedorf, V. Starlinger, A. Stier,

A. Tabelander, F. Vardar, S. Wizemann,

A. S. Pagan, G. Herdrich,

R. Laufer

Manfred Ehresmann ehresmann@ksat-stuttgart.de

10th IAA Symposium

21/04/2015

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Outline

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Mission Overview

CubeSat Atmospheric

Probe for Education

C. Montag, Session 7

Planetary Probe Design Workshop:

Collaboration Hands-On Small Satellite

Training for Engineering Students

R. Laufer, Session 7

A Service and Deorbit Module for

CubeSat Applications

M. Ehresmann, Poster Session 1

Programme Announcements:

CAPE Mission Patch

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Shape

• Adapted shape of

flown probes

→ Known flight

characteristic

• COG 45% x-axis MIRKA2 Dimensions

Deep Space 2 ReBR RED-Data2 MIRKA2

Mass [kg] 2.4 4.4 1.65 0.45

Max.Diameter [cm] 35 31 20 10

Table 1: Capsules with same Shape

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Inventory

• COTS paradigm coin for scale

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Inventory

Heat shield Small diameter → high expected heat loads

Very compact → high expected heat loads

Small nose radius → high convective stagnation

point heat flux

• Ablation Heat shield necessary

Candidates: RICA, ZURAM

RICA Sample

ZURAM

→ MIRKA2 is a test bed for

ablation materials 12MW/m² for 15s

14MW/m² for 22s

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Inventory

MIRKA2 Surface Sensor Arrangement

Scientific Payload

• Thermocouples

→ Heat Flux

→ Recession Rate

→ Flow Characteristic

• CN- Radiometer

→ Plasma composition

• IMU/GPS

→ Position and Attitude

• Pressure sensors

→ Flow Characteristic

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Inventory

Iridium QB9603

Communication

Sensor output rate: 84 Bps

Storage needed during blackout phase

• Iridium QB9603 Transmitter

Frequency: K-Band (1616 - 1626MHz)

Nominal data rate: 125 Bps

Effective short burst data rate: 35 Bps

→ Reduced sampling frequency

→ Prioritizing of data

→ on-board processing

Iridium & GPS Antenna

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Analysis

Tool: REENT

Initial conditions:

Determined by SDM

𝑣0 ≈ 7.54 km/s

𝛥𝑣𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑖𝑜𝑛 ≈ 0.54 m/s

γ ≈ 0.05°

h ≈ 120 km

(i ≈ 51.6°)

Fig 1:Trajectory MIRKA2

Baumann, Pagan, Herdrich:

Aerothermodynamic re-entry analaysis of

the cubesat-sized entry vehicle MIRKA2 → Long Reentry Duration

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Analysis

Specific enthalpy to

dissipate

ℎ𝑠 = 28.44 MJ/kg

Peak heating at 70 km

→ 𝑞𝑘𝑜𝑛𝑣 ≈ 2.5 MW/𝑚2

Conservative

assumptions

→ fully catalytic surface Fig 2: Convective heat flux Stagnation point MIRKA2

→ High Heat Flux

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Analysis

• Long reentry

duration

• High heat flux

Q ≈ 500 MJ/m²

Fig 3: Integral heat load MIRKA2

→ High Integral heat load

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Action Items

• Mission analysis Service and Deorbit Module → flight path angle ↑,

𝛥𝑣𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑖𝑜𝑛↑, apogee perigee control

• Heat shield Configuration

→ insulation, varying thickness

• Custom printed circuit board

→ OBC costs few hundred €

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Outlook

• Verifying electric system, communication, flight stability • Launch March 2016 Kiruna, Sweden

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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The End

Thank you for your attention!

KSat Team Beginning 2015

21/04/2015 CubeSat-sized re-entry Capsule

MIRKA2 www.ksat-stuttgart.de

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Le Backup

4/20/2015 MIRKA2-R Experiment 16

Flight Stability of the Capsule

• DLR, Supersonic and Hypersonic Technology Department [2]: • Aerodynamic investigations

→Confirmation of expected flight stability of the Mars Microprobe

Mars Microprobe [1]

• Mars Microprobe [1]

• Applied for ReBR and RED-Data2 • Allows stable flight • Deceleration down to subsonic speed • Requirement: Centre of gravity between

38% and 56% of total length from nose tip →Passive stabilisation enabled

Appendix

• Reentry Breakup Recorder (REBR) [3, 4]: • 3 successful flights • Transmission time of > 260 s with Iridium • After orbital return deceleration to subsonic speed • ballistic coefficient β=55.4 kg/m² • Centre of gravity: <56 % of total length from nose tip

• RED-Data2 [3, 4]: • Smaller version of REBR • Communication: Iridium • Ballistic coefficient β=42.9 kg/m² • Centre of gravity: 52% of total length from nose tip

→MIRKA2-R • Miniaturisation for CubeSat application (Iridium/Globalstar) • Ballistic coefficient β=50.4 kg/m² • Centre of Gravity: < 52% of total length from nose tip → Similar properities compared to ReBR and RED-Data2

Communication of the Capsule

4/20/2015 MIRKA2-R Experiment 17

Communication for existing ballistic capsules:

Dimensions in mm of ReBR and RED-DATA2 [4]

Diameter of MIRKA2-R capsule: 100 mm

Appendix

Design of the Experiment • MIRKA2 Capsule Data Budget

4/20/2015 MIRKA2-R Experiment 18

Datatype Amount of

Values [-] Bytes

Amount of

Sensors [-]

Sampling Rate

[Hz]

Total

(Bps)

Start integer 1 2 1 1 2

Thermocouple float 1 4 6 1 24

Battery

Voltage float 1 4 1 1 4

Radiometer float 1 4 1 1 4

Pressure float 1 4 2 1 8

IMU float 6 24 1 1 24

GPS float 4 16 1 1 16

End integer 1 2 1 1 2

Total (Bps) 84,00

Appendix