ACE includes a 95% efficient, single-operating point PPU for 400W and 500W set points that is radiation tolerant to 50 kRad TID and has evolved significantly over the past 2 years in both capability and footprint. This PPU has successfully operated thrusters in thermal vacuum chambers, has been radiation tested, and has been shock and random vibration tested.
The design choice to standardize a single operating set point was made to reduce complexity, mass, and volume. While many PPUs are the size of a desktop PC, ACE’s PPU is a single circuit board.
|INPUT POWER||400 W|
|INPUT VOLTAGE||22-38 VDC (unregulated)|
In early 2018, Apollo's PPU for LEO had 70 active components and only tolerated a total ionizing dose of 10 kRad. Later that year, Apollo completed a radiation hardened PPU redesign for a US government customer in less than 6 months.
Rapid design improvements came when Apollo acquired team members experienced in the design and assembly of flight hardware which flew on Planet Labs and SpaceX missions. Apollo also performed multiple rounds of proton bombardment testing, and performed additional rounds of shock/vibe testing.
|Advanced simulations & prototype iteration with Google-derived high reliability software practices||Parts screening||Radiation testing||Shock/vibe testing||LEO PPU||GEO PPU|
|Added team from||Stanford||Planet||SpaceX|
|Collaborated with||RTS||UC Davis||Planet|
|Rad tolerance||10 kRad||10 kRad||25 kRad||100 kRad||50 kRad||100 kRad|
|Active (distinct) parts||70||70||70||14||14||14|
|Mass||1.5 kg||1.5 kg||2.5 kg||1.5 kg||1.5 kg||1.5 kg|
The PPU is now radiation hardened by design, replacing any failure-prone microprocessors with simple and reliable components wherever possible. The design prevents gate ruptures and latchups, is tolerant of transients and upsets, and is suitable for missions from LEO through the Van Allen belts to GEO.
To deliver AXE as part of a fully integrated EP subsystem, Apollo has designed a 1,000 W ~95% efficient, single board PPU based on the existing 400 W PPU. The design of the 400 W PPU is qualified and has a clear path to delivering 1,000 W of discharge power.
Apollo and our suppliers are completing qualification testing in line with ESA, MIL and ISO standards. Test flow plans, test order, test procedures, and test levels are set to meet or exceed the performance, physical, electrical, environmental, thermal, and radiation requirements set by customer agreements. Learn more
Apollo's research and development lab has five vacuum chambers and one thermal-vac chamber, allowing for hundreds of tests per week. This has enabled the development of new system designs in weeks instead of years. These facilities are fault-tolerant by design and able to grow to enable acceptance testing of hundreds of systems per month. Learn more
Apollo has partnered with a high-volume aerospace manufacturing partner based in Silicon Valley. Apollo’s manufacturing partner specializes in high reliability aerospace and defense products and has the capacity to produce hundreds of units per month to Apollo Fusion customer specifications. Learn more