SPACE INDEX COMPANIES INSIGHTS SECTORS PRODUCTS NEWS BLOG ANSWERS RESEARCH ABOUT FOR COMPANIES BUILD / 2026.06.04
Phase Four logo Phase Four Developed electrodeless radio-frequency and multi-mode electric propulsion systems for satellites vs Zeno Power Develops radioisotope power systems that convert heat from decaying isotopes into years of reliable electricity for lunar surface and seabed missions Zeno Power logo
HEAD-TO-HEAD2 shared sectors
Phase Four Zeno Power
Founded 2015 2018
Headquarters Hawthorne, California Washington, District of Columbia
Type private private
Status closed operating
Employees 5 79
Total funding $35.8M $94.9M
Latest round Series C Series B
Sectors Space Propulsion, Satellite Components & Subsystems Satellite Components & Subsystems, Lunar Services, Space Propulsion
Products listed 4 2
Federal contracts
Launches
Leaders listed Steve Kiser, M. Umair Siddiqui, Simon Halpern Tyler Bernstein, Jonathan Segal, Jacob Matthews
News mentions 0 0
SHARED SECTORS
FREQUENTLY ASKED

How do Phase Four and Zeno Power compare?

Both companies work in Space Propulsion, Satellite Components & Subsystems. Phase Four was founded in 2015 and Zeno Power in 2018.

Which is larger, Phase Four or Zeno Power?

Zeno Power reports the larger workforce, with 79 employees versus 5.

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