Does NASA still plan for the Mars Ascent Vehicle to burn wax from the surface to orbit?

Question

The NASA news item From Pedicures to the Peregrine Rocket, Paraffin Wax Proves Its Worth says:

The paraffin-based fuel also works under challenging environmental conditions, like the very low temperatures found on the surface of Mars. The Mars Ascent Vehicle, currently under development by NASA’s Jet Propulsion Laboratory, aims to use the paraffin technology to return a sample from the surface of the planet to an orbiting spacecraft.

Two and a half years on, have the tests gone well? Is paraffin still the plan?

For more, see the (currently unanswered) question Why NASA's sudden (apparently) interest in Wax hybrid engines? Which property is so attractive now?

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Answer 1

Its still in active development. Two options for the sample return ascent vehicle are being worked, either a single-stage paraffin-MON hybrid vehicle or a two-stage solid fueled vehicle. No decision has been made yet on which will be selected (if the program continues at all, given Starship etc). Both options have similar mass, payload capacity, system complexity, expected reliability. Hybrid option is expected to hold up a bit better in the thermal environment it'll be subjected to (years of cold-storage in transit/on the surface), but these problems aren't insurmountable for the solid option. Solids are more proven though

Hybrid motor testing seems to still be at the proof of concept stage. They've not tested a flightlike motor. Significantly smaller than the real thing would be, at low-percentage MON, and with non-flightlike addons. Lots of problems with nozzle erosion too, for which no promising solution has been found

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20190002123.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20190027423.pdf