The Microwave Radiometer

Technology Acceleration CubeSat (MiRaTA)

Kerri Cahoy, J.M. Byrne, T. Cordeiro, P. Davé, Z. Decker, A. Kennedy, R. Kingsbury, A. Marinan, W. Marlow, T. Nguyen, S. Shea MIT STAR Laboratory

William J. Blackwell, G. Allen, C. Galbraith, V. Leslie, I. Osaretin, M. DiLiberto, P. Klein, M. Shields, E. Thompson, D. Toher, D. Freeman, J. Meyer, R. Little MIT Lincoln Laboratory Neal Erickson, UMass-Amherst Radio Astronomy Rebecca Bishop, The Aerospace Corporation

Space Telecommunications, Astronomy, and Radiation Lab

This work is sponsored by the National Oceanic and Atmospheric Administration under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government. Outline

• Introduction and Motivation • MiRaTA Goals – Microwave Radiometer – GPS Radio Occultation • MiRaTA Status – MicroMAS lessons learned – MiRaTA status • Next Steps

MicroMAS Launched July 13, 2014 Orb-2 Antares/Cygnus Deployed March 4, 2015 International Space Station Courtesy NASA/NanoRacks

ESTF 2015- 2 KC, WJB 6/15/2015 New Approach for Microwave Sounding

Microsized Microwave Suomi NPP Satellite Atmospheric Satellite Launched Oct. 2011 (MicroMAS) Deployed Mar. 2015

Advanced Technology Microwave Sounder 4.2 kg, 10W, 34 x 10 x 10 cm (ATMS) • Miniaturized microwave sensor aperture (10 cm) • Broad footprints (~50 km), modest pointing requirements • Relatively low data rate (kbps) NASA/GSFC 85 kg, 130 W 2200 kg spacecraft • Perfect fit for a CubeSat! instrument NPP: National Polar-orbiting Partnership

ESTF 2015- 3 KC, WJB 6/15/2015 Outline

• Introduction and Motivation • MiRaTA Goals – Microwave Radiometer – GPS Radio Occultation • MiRaTA Status – MicroMAS lessons learned – MiRaTA status • Next Steps

ESTF 2015- 4 KC, WJB 6/15/2015 Microwave Radiometer Technology Acceleration (MiRaTA)

• Two science instruments on a 3U CubeSat:

• Tri-band microwave radiometer - Temperature (~60 GHz, V-band) - Water vapor (~183 GHz, G-band) - Cloud ice (~207 GHz, G-band) - Absolute calibration better than 1 K

• GPS radio occultation receiver (GPSRO) - Called the Compact TEC Atmospheric GPSRO System (CTAGS) - Atmospheric temperature, pressure profiles - Ionospheric electron density and Total Electron Content (TEC)

• Goal: Demonstrate both payloads and use GPSRO to calibrate the radiometer by sounding overlapping volumes of atmosphere.

ESTF 2015- 5 KC, WJB 6/15/2015

• Calibration proof of concept using limb measurements and GPS-RO – Observe coincidental radiometric and GPS-RO atmospheric density information – Enabled by high-performance COTS GPS receivers with low size, weight, and power

• Funded by NASA Earth Science Technology Office (ESTO) MiRaTA Space Vehicle

Acronym key:

CTAGS, NovAtel OEM-628 + LNA CTAGS, PIM Payload NovAtel Interface Module OEM-628 Radiometer Assembly IFP Intermediate Frequency Processor

EPS Electrical Power System PIM CTAGS 3U Double- LNA Low Noise Deployable IFP LNA Amplifier for Solar Panels GPSRO Cadet Radio MAI-400 Maryland Motherboard Aerospace Inc. Batteries Bus ADCS Attitude Stack Determination and EPS Control

EHS Earth Horizon Sensors MAI-400 (ADCS) EHS

ESTF 2015- 6 KC, WJB 6/15/2015 Overlapping GPSRO and Radiometer

Progression of the tangent point for an ingress (setting) occultation

DN(q, f, lat, lon) N(h, lat, lon)

Modification of image from Lidia Cucurull

ESTF 2015- 7 KC, WJB 6/15/2015 MiRaTA Calibration Maneuver

~ 20 minute maneuver 0.5° / sec rate

ESTF 2015- 8 KC, WJB 6/15/2015 Radiometer and GPSRO Simulation

• Single set of GPS SV tracks over 24 hrs as rx’d by MiRaTA. • Plot area is anti-ram FOV of MiRaTA GPS antenna array (85° x 30° full beamwidth) • Post-LNA gain (dB) shown for L1. Goes to 5 dB at 81 km tangent height. • Green bands show where radiometer field of view overlaps with GPSRO measurements.

ESTF 2015- 9 KC, WJB 6/15/2015 Radiometer (UMass Amherst & MIT LL)

V-band RFE

Calibration load Ultra-compact IF Spectrometer (V-band)

Wideband G-band RFE

Components of the same color are in the same block.

UMass Amherst has fabricated prototype blocks

ESTF 2015- 10 KC, WJB 6/15/2015 Science Payload Antennas

• CTAGS GPSRO Patch Array Antenna fabricated – Successful mechanical inspection completed – Electrical testing ongoing • Radiometer Reflector Antenna Fabricated – Successful mechanical inspection completed – Electrical testing complete; data under analysis

Radiometer Reflector Antenna

CTAGS Patch Array Antenna

ESTF 2015- 11 KC, WJB 6/15/2015 Science Payload Modules

• Designs implemented; boards fabricated and testing of payload hardware is ongoing • Engineering Design Units fabricated for critical payload components

EDU PIM Board EDU PVRM Board FM DRO Module

FM V-RFE Internal Layout FM G-RFE-1 Module V-RFE Mechanical Module

ESTF 2015- 12 KC, WJB 6/15/2015 Outline

• Introduction and Motivation • MiRaTA Goals – Microwave Radiometer – GPS Radio Occultation • MiRaTA Status – MicroMAS lessons learned – MiRaTA status • Next Steps

ESTF 2015- 13 KC, WJB 6/15/2015 MicroMAS Debrief: Intro

• MicroMAS 3U CubeSat - 34 x 10 x 10 cm, 4.252 kg - 10 W average power - 118 GHz radiometer payload • 3D atmospheric temperature

• MicroMAS deployed March 4, 2015 - Successful downlinks March 4, 5, 9 - Radio transmitter issue - Unable to validate radiometer - Panels and antenna deployed - Power system and battery nominal - Obtained ADCS sensor data: IMU, magnetometer, EHS, sun sensors - Turned on MAI-400, reaction wheels • Wheels responded but unable to validate ADCS algorithms

ESTF 2015- 14 KC, WJB 6/15/2015 MicroMAS Earth Horizon Sensors while tumbling

EHS A (Side) Measurements

4000 Limb 3500 Sky Earth 3000 Side-looking EHS is on the same side as panel YN Wide FOV

2500

2000

ADC Count ADC 1500

1000 500 Room Temp ~1400 counts 0 18:54:00 18:54:43 18:55:26 18:56:09 18:56:52

EHS B (AntiRam) Measurements 4000 Limb 3500 Sky Sun Earth 3000 Wide FOV

2500

2000

ADC Count ADC 1500

1000 Space

500

0 18:54:00 18:54:43 18:55:26 18:56:09 18:56:52

ESTF 2015- 15 KC, WJB 6/15/2015 MicroMAS lessons learned

• Redundant radio needed – Implementing low-rate UHF radio on MiRaTA in addition to Cadet • TLEs for ISS-deployed CubeSats not as good as predicted – Compare Riesing (SmallSat 2015) to Coffee et al., 2013 • Flight spares are a good idea • Ensure all ADCS sensor parameters are tunable in case they are mis-labeled in code or have biases • Power reset management is important tool • Increased battery heating

ESTF 2015- 16 KC, WJB 6/15/2015 MiRaTA Status

• Procurement of major COTS components nearly complete – Have Cadet radios, Pumpkin motherboard, Clyde Space EPS – Expecting Clyde Space solar panels, batteries, MAI-400 reaction wheel assembly and Earth Horizon sensors (MAI-400 electronics boards complete) • Custom bus and payload components nearing completion – Have prototype avionics and interface boards – Have engineering unit payload modules – Flight model radiometer and GPSRO antennas fabricated • Build of Mass Mockup and Ground Support Equipment for functional and environmental testing is underway • Critical Design Review was June 1-3, 2015 • Still do not know what our launch/orbit will be (NASA CSLI) – Hoping for an SSO opportunity, but could work with ISS deployment

ESTF 2015- 17 KC, WJB 6/15/2015 MiRaTA / MicroMAS Testing

TVAC 4-coil Merritt design Helmholtz cage

ADCS Suspension Test “Piñata” Payload Calibration

Payload Spin Balance 3-Axis Air Bearing Test

ESTF 2015- 18 KC, WJB 6/15/2015 Payload TVAC for Radiometric Calibration

Cold target

Payload

Ambient target • Detailed simulations of payload thermal (cyan) and radiometric environment (red, green, blue) • Assessments were made of: Motor and – Sensitivity reflector – Absolute accuracy Variable target – Linearity – Stability

ESTF 2015- 19 KC, WJB 6/15/2015 MicroMAS Radiometer Performance Accuracy and Precision

3! 2

1.8 2! 1.6

1.4 1!

1.2

0! 1

0.8 NEDT (K) NEDT Accuracy(K) -1! 0.6 Tropospheric channels

0.4 -2! 0.2

-3! 0 1 2 3 4 5 6 7 8 9 100! 150! 200! 250! 300! 350! Scene Temperature (K) Channel

ATMS equivalent spot size; 250 K payload temperature

ESTF 2015- 20 KC, WJB 6/15/2015 MiRaTA Ground & Data Segment

MiRaTA overpass MiRaTA

Low-rate UHF, 400 MHz: TLM High-rate UHF, 468 MHz: High-Gain UHF TLM, DATA Ground Station Mission Operations Center Ground UHF, 450 MHz: S/C Health CMD

LL Commands Wallops Commands Flight Facility SDL Mission Planning Mission (VA, USA) Command MIT LL and USU SDL

TLEs

Data Processing Center JSpOC Data Product Derivation Public Two-Line TLEs All Data and Archival FTP Elements Site Lvl 0 Lvl 1 Lvl 2 MIT campus

ESTF 2015- 21 KC, WJB 6/15/2015 Outline

• Introduction and Motivation • MiRaTA Goals – Microwave Radiometer – GPS Radio Occultation • MiRaTA Status – MicroMAS lessons learned – MiRaTA status • Next Steps

ESTF 2015- 22 KC, WJB 6/15/2015 Summary and Next Steps

• There remains a need for near real-time, persistent, high- resolution and accurate global measurements of weather systems – Traditional aerospace approaches have budget and risk constraints that are at odd with improving temporal and spatial sampling – This directly compromises the science – Discoveries are often made using oversampled data • Reveals effects, behaviors, dependences that are not captured in models • Tropical storms and hurricanes cause $5B of damage and property loss in the US alone each year – Estimated losses of 10,000 lives each year globally • Nanosatellite sounding constellations will improve predictions and support more advanced and accurate warnings • MiRaTA demonstrates performance of radiometer and CTAGS – MiRaTA EM functional testing Summer 2015 – Flight SV Integration and Test activities Summer/Fall 2015

ESTF 2015- 23 KC, WJB 6/15/2015 Acknowledgments

This work is supported by NASA Earth Science Technology Office grant number NNX14AC75G and NASA Space Technology Research Grant NNX12AM30H. This work was also sponsored by the National Oceanic and Atmospheric Administration under Air Force contract FA8721-05-C-0002.

One graduate student is supported by a National Science Foundation Graduate Research Fellowship under Grant No. 1122374. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Opinions, interpretations, conclusions, and recommendations are those of the authors and not necessarily endorsed by the United States Government.

Thank you to our full team of research staff, graduate students, co-ops, interns, undergraduates and support staff.

ESTF 2015- 24 KC, WJB 6/15/2015 Backup

ESTF 2015- 25 KC, WJB 6/15/2015 Architecture Studies Show Great Promise for Constellation Approaches 3 Satellites, one per plane 24 Satellites, eight per plane

9 .7 60 60 Mean revisit time (hours) Mean revisit 8 time (hours) Mean revisit .6 40 40 7 20 20 .5 6 0 0 5 .4 Latitude Latitude -20 Latitude 4 -20 .3 -40 3 -40 .2 -60 2 -60

-150 -100 -50 0 50 100 150 -150 -100 -50 0 50 100 150 Longitude Longitude

ESTF 2015- 26 KC, WJB 6/15/2015 MicroMAS Operational Data Flowchart

Step 3

Step 1

Step 4 Lvl0a Decoded & Lvl0b Lvl0c Demodulated Cadet Packets

Step 2

Data Product Description Level 0a Raw I/Q samples from USRP N210 containing L-3 Cadet packets Level 0b Decoded & demodulated L-3 Cadet packets Level 0c Ingested MicroMAS packets with units converted and timestamped Level 1a Calibrated & geolocated antenna temperatures at native resolution

ESTF 2015- 27 KC, WJB 6/15/2015 MiRaTA Space Vehicle

• Payload – Tri-band microwave radiometer – GPS radio occultation receiver with patch antenna array (on back)

• Bus – L-3 Cadet UHF radio* (3 Mbps) – Low-rate backup UHF radio (2.4 kbps) – Pumpkin PIC24F motherboard with Salvo RTOS* – Clyde Space EPS*, battery*, and double-sided deployed solar panels – MAI-400 reaction wheels + Earth Horizon Sensors* – Custom interface boards

*flown on MicroMAS

ESTF 2015- 28 KC, WJB 6/15/2015