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JPL Advanced Micro Sun Sensor → Prox-1 (2019)

Category: Delivered but Descoped (Prox-1 removed sensor before launch) | Confidence: Confirmed
Last updated: 2026-04-07 (Session 95)

Summary

JPL's miniature digital sun sensor — originally developed for Mars Science Laboratory (didn't make the cut) — was delivered to Georgia Tech for integration on the Prox-1 small satellite (~2015). However, Prox-1 was significantly descoped in 2017 due to flight computer software issues: the proximity operations mission was dropped, and the satellite no longer featured the sensor, propulsion elements, or solar cells when it launched June 25, 2019 on Falcon Heavy STP-2. Prox-1 was reduced to a deployment vehicle for LightSail 2 and an optical target for orbit determination research.

Correction (Session 95): This page previously stated the sun sensor was validated in orbit on Prox-1. That is incorrect — the sensor was delivered to Georgia Tech but removed during the 2017 descoping. The FO project matured the sensor to TRL 6 via balloon test, and JPL delivered hardware to a partner, but the orbital validation never occurred. The TechPort record's link to the Prox-1 NSSDC page is misleading — it reflects the intended destination, not actual flight.

FO Project

12284 — Advanced Micro Sun Sensor

  • Period: 2012-09-01 – 2015-09-30 | TRL: 5 → 6
  • PI: C. Christian Liebe (JPL) | Co-I: Neil Milburn
  • Technology developed at JPL 2000–2004; qualified for MSL but not selected
  • FO: Balloon test to 125,000 feet — validated in near-space conditions
  • TRL description says the sensor is "a pathfinder for a new generation of sun sensors and has inspired a handful of other similar developments around the world"
  • Library items in TechPort directly link to Prox-1 NSSDC page (2019-036A) — JPL explicitly tracked this infusion

Downstream: Prox-1 (Georgia Tech) — DESCOPED

  • Mission: Prox-1 — a 154-pound small satellite designed, fabricated, and tested by Georgia Tech graduate students over 5+ years
  • JPL role: Delivered the micro sun sensor hardware to Georgia Tech (~2015); provided technical support
  • Partners: U.S. Air Force (primary funder), Georgia Space Grant Consortium, The Aerospace Corporation, Raytheon Vision Systems, JPL
  • Launch: June 25, 2019 — SpaceX Falcon Heavy, STP-2 mission (Space Test Program 2)
  • Original mission objective:
  • Demonstrate automated proximity operations and trajectory control based on relative orbit determination via passive imaging
  • Deploy LightSail B (Planetary Society's 3U solar sail CubeSat) and fly in close proximity
  • Provide first-time orbital flight validation of the advanced micro sun sensor technology
  • 2017 descoping: Due to flight computer software issues, Prox-1 was significantly descoped. The proximity operations mission was dropped. The sun sensor, propulsion elements, and solar cells were removed from the satellite. Prox-1 was reduced to: (1) LightSail 2 deployer and (2) optical target for attitude/orbit determination research of space objects.
  • Result: Prox-1 successfully deployed LightSail 2 but did not carry or validate the JPL micro sun sensor
  • Source: Gunter's Space Page (space.skyrocket.de/doc_sdat/prox-1.htm) — widely used authoritative satellite reference

Technology Chain

Stage Date Event TRL
JPL internal development 2000–2004 Original miniature sun sensor created ~4
MSL evaluation 2004+ Qualified for MSL but not selected 5
FO balloon test 2012–2015 Near-space validation at 125,000 ft 5→6
Delivered to Georgia Tech ~2015 Integration on Prox-1 (intended) 6
Prox-1 descoped 2017 Sun sensor removed from satellite —
Prox-1 launch Jun 25, 2019 Launched WITHOUT sun sensor —

Confidence Assessment

  • FO balloon validation: Confirmed (TechPort [12284], TRL 5→6)
  • Delivery to Georgia Tech: Confirmed (FO website: "micro sun sensor was delivered to Georgia Tech's Prox-1 Mission in 2015")
  • Prox-1 descoping: Confirmed (Gunter's Space Page: satellite "no longer featured the sensor and propulsion elements" after 2017 descoping)
  • Sun sensor did NOT fly on Prox-1: Confirmed (sensor removed before 2019 launch)
  • TechPort misleading: The [12284] library items link to Prox-1 NSSDC entry, which creates a false impression of flight heritage. TechPort recorded the intended destination, not the actual outcome.
  • Dollar amounts: Not found — Prox-1 was funded through U.S. Air Force Space Test Program

Key Insight

Session 95 correction: This page previously presented the Micro Sun Sensor as a clean "JPL → FO → university mission infusion" story. The reality is more nuanced and cautionary:

  1. The FO project succeeded — balloon test to 125,000 ft validated the sensor at TRL 6
  2. JPL delivered hardware — the sensor reached Georgia Tech for Prox-1 integration
  3. The mission partner failed — Prox-1's flight computer issues led to descoping that removed the sensor
  4. The orbital validation never happened — the sensor remains at TRL 6, not TRL 7+

This is a "last-mile failure" archetype — FO matured the technology and a mission host was found, but the host mission's own problems prevented the final step. The TechPort record is misleading because it links to the intended mission (Prox-1/NSSDC) without noting the descoping. This is a data quality finding: TechPort library items can reflect aspirational rather than actual outcomes.

The sensor's description notes it is "a pathfinder for a new generation of sun sensors and has inspired a handful of other similar developments around the world" — the technology influence may persist through these inspired designs even without the Prox-1 flight.