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TERSat

Massachusetts Instituteof TechnologyEric Peters, Danilo Roascio, Leonard Tampkins, Kezi Cheng

June 29, 2012

11Mission BackgroundRadiation in Earth orbit harms satellitesNatural radiation: High energy particles from solar wind are trapped in Van Allen BeltsMan-made: high altitude nuclear activityGap in radiation belts is caused by lightning Can we scatter radiation particles by emitting VLF waves, like lightning?2SOHO composite image by Steve Hill (NASA)

Van Allen Belts

Stanford VLF group image(TERSat)s mission: investigate the ability of space-based Very Low Frequency (VLF) radio transmission to reduce the population of harmful high-energy particles in the inner Van Allen radiation belts.

2Mission OverviewSatellite Goals: Demonstrate wave-particle interaction within the inner Van Allen belts Transmit VLF waves at LEO altitude Demonstrate science behind potential radiation remediation techniqueSHOT II Goal:Use VLF wave transmitter to demonstrate ability to transmit signal to a receiver on the groundConnection:Demonstrates payload concept of operations, tests prototype VLF receiver parts

Example TERSat Interaction with DSX

Mini-demo3Satellite Goals: Will radiate VLF waves between 3-50khz, receive VLF waves from itself and DSX 3

SHOT Design Overview4- Discuss the details of your SHOT II design> Include mechanical, electrical, software- Drawings and actual pictures are expected- Include a functional block diagram (should make sense logically)-Hardware used- Discuss User Guide Compliance (i.e. weight, flight string attachment, RF, labeling etc) - Answer the question How you are going to complete your mission with this design.

4Payload Design StructureFoam BoxTwo antennas:17 kHz copper coil along perimeter34 kHz aluminum plates on long sidesStructure:Foam box with high impact foam on bottom to mount electronics

Weight: 1.45 kg

Dimensions: 8.5 x 11 x 5

Mylar for thermal insulation

Balloon attachment cord runs through middle of payload

5Connected to oscillator17kHz coil34kHz plates (higher freq give easier readings)56Payload Design Electronics

Circuit design includes:Crystal oscillator for frequency stabilityPayload AmplifierMorse code keyer

2 Voltage Data Loggers with peak detector conditioning to evaluate power going into aluminum plates+

Ground Station DesignEttus USRP SDR ReceiverLow-frequency daughter boardsSampling between 0 and 125 kH

Custom Low Noise Amplifier tuned to operate between 1kHz and 80 kHz

Attached to square loop antenna

7Software defined reciever 7SHOT Functional Testing8Received signalLot of noise in VLF bandMorse Keying helps identify signalMorse code: Hello WorldCooling TestFirst prototype not insulated enough

Second prototype Thicker foam + Mylar sheet show better thermal insulation

- Discuss your test program for you SHOT II design- Prove your project is ready for flight- Show test data (graphs, charts, etc) that are labeled, with key events indicated- Structural tests should be included but equal time should be devoted to mission/science tests (present mission/science test first)- Proof should be shown that you have actually recorded, off-loaded, and analyzed your data- Discuss the expected results and what conclusions you expect to make from these resultsThis should be detailed and include examples of test dataVisible readings of a signal that is recognizably ours on laptop connected to receiver on the ground

8Mechanical TestingDrop Test

Whip TestStair TestDrop TestSuccessful!Battery held downBox maintained shapeScrews were set9Demonstration

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