Phase Four Awarded $14.9M Contract by DARPA to Develop Electric Propulsion for VLEO Satellites

Phase Four Awarded $14.9M Contract by DARPA to Develop Electric Propulsion for VLEO Satellites

Phase Four, one of the leading providers of next-generation electric propulsion (EP) solutions for satellites, was awarded a $14.9M contract by the Defense Advanced Research Projects Agency to deliver an "air-breathing" EP system to enable extended satellite operations in Very Low Earth Orbit (VLEO), at altitudes as low as 90-450 km.

The award is part of DARPA's Otter program, which aims to develop, demonstrate, and collect on-orbit data for "air breathing" electric propulsion technologies that will harvest ambient low-density air as propellant, enabling extended satellite operations at VLEO altitudes. The Otter program will culminate in a long duration "orbiting wind tunnel" spaceflight demonstration, characterizing the performance of the "air-breathing" EP system in the orbital environment.

DARPA's Otter program will leverage Phase Four's innovative core technology, the radio frequency thruster (RFT), which is inherently propellant agnostic compared to legacy electric propulsion systems which rapidly degrade when exposed to non-traditional propellants. This feature uniquely enables the RFT to operate on the low-density air harvested in the VLEO environment. The Otter program will build upon a previous effort with DARPA that developed a proof-of-concept thruster prototype for novel, low-cost propellants.

"Phase Four is proud to continue supporting DARPA's efforts to advance in-space propulsion capabilities," said Umair Siddiqui, Phase Four's President and CTO, and Principal Investigator for the effort. "Phase Four has designed and built electric propulsion systems that have been launched on 9 satellites with over 5,300 days of on-orbit flight heritage since the company was founded. We're thrilled to bring that heritage, experience, and innovation in electric propulsion systems to the Otter program."

"With the addition of the Otter program, Phase Four's portfolio of propulsion capabilities will now span the totality of the space domain, from near-space to deep space," added Jason Wallace, President of Government Programs at Phase Four. "We look forward to working closely with DARPA to unlock sustained missions in VLEO, which will increasingly become a critical operational environment for national security as traditional orbits become congested and contested."

Click here to learn about Satellite Thrusters from Phase Four listed on SatNow.

Publisher: SatNow

GNSS Constellations - A list of all GNSS satellites by constellations


Satellite NameOrbit Date
BeiDou-3 G4Geostationary Orbit (GEO)17 May, 2023
BeiDou-3 G2Geostationary Orbit (GEO)09 Mar, 2020
Compass-IGSO7Inclined Geosynchronous Orbit (IGSO)09 Feb, 2020
BeiDou-3 M19Medium Earth Orbit (MEO)16 Dec, 2019
BeiDou-3 M20Medium Earth Orbit (MEO)16 Dec, 2019
BeiDou-3 M21Medium Earth Orbit (MEO)23 Nov, 2019
BeiDou-3 M22Medium Earth Orbit (MEO)23 Nov, 2019
BeiDou-3 I3Inclined Geosynchronous Orbit (IGSO)04 Nov, 2019
BeiDou-3 M23Medium Earth Orbit (MEO)22 Sep, 2019
BeiDou-3 M24Medium Earth Orbit (MEO)22 Sep, 2019


Satellite NameOrbit Date
GSAT0223MEO - Near-Circular05 Dec, 2021
GSAT0224MEO - Near-Circular05 Dec, 2021
GSAT0219MEO - Near-Circular25 Jul, 2018
GSAT0220MEO - Near-Circular25 Jul, 2018
GSAT0221MEO - Near-Circular25 Jul, 2018
GSAT0222MEO - Near-Circular25 Jul, 2018
GSAT0215MEO - Near-Circular12 Dec, 2017
GSAT0216MEO - Near-Circular12 Dec, 2017
GSAT0217MEO - Near-Circular12 Dec, 2017
GSAT0218MEO - Near-Circular12 Dec, 2017


Satellite NameOrbit Date
Kosmos 2569--07 Aug, 2023
Kosmos 2564--28 Nov, 2022
Kosmos 2559--10 Oct, 2022
Kosmos 2557--07 Jul, 2022
Kosmos 2547--25 Oct, 2020
Kosmos 2545--16 Mar, 2020
Kosmos 2544--11 Dec, 2019
Kosmos 2534--27 May, 2019
Kosmos 2529--03 Nov, 2018
Kosmos 2527--16 Jun, 2018


Satellite NameOrbit Date
Navstar 82Medium Earth Orbit19 Jan, 2023
Navstar 81Medium Earth Orbit17 Jun, 2021
Navstar 78Medium Earth Orbit22 Aug, 2019
Navstar 77Medium Earth Orbit23 Dec, 2018
Navstar 76Medium Earth Orbit05 Feb, 2016
Navstar 75Medium Earth Orbit31 Oct, 2015
Navstar 74Medium Earth Orbit15 Jul, 2015
Navstar 73Medium Earth Orbit25 Mar, 2015
Navstar 72Medium Earth Orbit29 Oct, 2014
Navstar 71Medium Earth Orbit02 Aug, 2014


Satellite NameOrbit Date
NVS-01Geostationary Orbit (GEO)29 May, 2023
IRNSS-1IInclined Geosynchronous Orbit (IGSO)12 Apr, 2018
IRNSS-1HSub Geosynchronous Transfer Orbit (Sub-GTO)31 Aug, 2017
IRNSS-1GGeostationary Orbit (GEO)28 Apr, 2016
IRNSS-1FGeostationary Orbit (GEO)10 Mar, 2016
IRNSS-1EGeosynchronous Orbit (IGSO)20 Jan, 2016
IRNSS-1DInclined Geosynchronous Orbit (IGSO)28 Mar, 2015
IRNSS-1CGeostationary Orbit (GEO)16 Oct, 2014
IRNSS-1BInclined Geosynchronous Orbit (IGSO)04 Apr, 2014
IRNSS-1AInclined Geosynchronous Orbit (IGSO)01 Jul, 2013