SPACE INDEX COMPANIES INSIGHTS SECTORS PRODUCTS NEWS BLOG ANSWERS RESEARCH ABOUT FOR COMPANIES BUILD / 2026.06.03
Phase Four logo Phase Four Developed electrodeless radio-frequency and multi-mode electric propulsion systems for satellites vs Space Solar Develops space-based solar power technology to beam continuous clean energy from geostationary orbit to Earth via wireless power transmission Space Solar logo
HEAD-TO-HEAD1 shared sector
Phase Four Space Solar
Founded 2015 2022
Headquarters Hawthorne, California, USA Didcot, Oxfordshire, United Kingdom
Type private private
Status closed operating
Employees 5 10
Total funding $35.8M $508K
Latest round Series C Seed
Sectors Space Propulsion, Satellite Components & Subsystems Satellite Manufacturing, Satellite Components & Subsystems
Products listed 4 2
Federal contracts
Launches
Leaders listed Steve Kiser, M. Umair Siddiqui, Simon Halpern Martin Soltau, Sam Adlen, David Homfray
News mentions 0 0
SHARED SECTORS
FREQUENTLY ASKED

How do Phase Four and Space Solar compare?

Both companies work in Satellite Components & Subsystems. Phase Four was founded in 2015 and Space Solar in 2022.

Which is larger, Phase Four or Space Solar?

Space Solar reports the larger workforce, with 10 employees versus 5.

Numbers refresh on every render against the live Space Index database. Federal contract data from USAspending.gov; launches from LaunchLibrary2.