Costs can't be usefully calculated this way, as the crew compartment weight
is likely more than that of the crew. Further, the propellant almost isn't
isn't sulfur based, which would represent a large cost saving (albeit only
for the final part of the flight).
Andrew
On Wed, 28 Dec 2022, 19:22
https://zephalto.com/en/
Zephalto is a start-up backed by the French spatial agency CNES that positions
itself on low-carbon and safe "space" travel in the stratosphere at 25 km. I
couldn't find what low carbon means on their web site, but I've read a French
media quoting 27 t CO2eq per
