Zubrin Comments on New Independent Report on Human Mars Mission

According to an article by Jeff Foust in the April 18th issue of Space News, an “Independent report concludes that a 2033 human Mars mission is not feasible.”

Foust reports: “STPI (the Science and Technology Policy Institute) at NASA’s direction, used the strategy the agency had laid out in its ‘Exploration Campaign’ report, which projects the continued use of the Space Launch System and Orion and development of the lunar Gateway in the 2020s. That would be followed by the Deep Space Transport (DST), a crewed spacecraft that would travel from cislunar space to Mars and back….That work, the STPI report concluded, will take too long to support a 2033 [Mars orbital] mission.”

Commenting on this news, Mars Society President Dr. Robert Zubrin said, “While I would love to dispute this report, it actually understates the problem. If one accepts NASA’s ‘Exploration Campaign’ – including SLS, Orion, Gateway, and DST as necessary, there is no way NASA would be able to do even a Mars orbital mission, let alone landing, by 2033, or 2133 for that matter, as it is questionable whether any agency so irrational as to embrace NASA’s current Mars mission plan would ever be able to send humans to Mars at all.”

“Neither the the Gateway nor Orion is useful for a Mars mission, as Gateway is useless for anything and Orion is seriously overweight compared to available alternatives such as Dragon (26 tons vs 10 tons.) SLS, while offering some new capability, is overpriced compared to the already operational Falcon Heavy, and inferior in all metrics to the SpaceX Starship now under development.

“But the truly crazy part of the NASA Mars mission plan is the Deep Space Transport. This system would use electric propulsion (EP) to travel from the Gateway to Mars and back with one-way trip times of 300 days. This contrasts poorly with what chemical propulsion can already do, as demonstrated by the Spirit, Opportunity and Insight missions, which reached Mars in 180 days starting from LEO.

Furthermore, if a spacecraft were at the Gateway, it could get to Mars using chemical propulsion using less propellant than EP, despite EP’s higher exhaust velocity, because the velocity change required to reach the Red Planet from the Gateway by EP is 7 km/s, while using chemical propulsion it is only 0.7 km/s. But in addition the EP spaceship needs to carry a huge 500 kWe electrical power system to drive its engines, while the chemical rocket propelled vessel only needs 10 kWe for life support. So by implementing the futuristic DST, NASA is proposing to create a system which will get astronauts to Mars in twice the time, with twice the dry mass, twice the wet mass and a much higher development cost than could be achieved using currently available off-the-shelf chemical rockets.

“Furthermore, as if that weren’t enough, the DST uses xenon propellant, which is not obtainable from the Moon, as opposed to the oxygen/hydrogen propellant used by a chemical rocket which conceivably could be. So the choice of using the unnecessary, slow, costly and  mission bloating DST for Mars missions completely negates any hope that the lunar base could play a useful role in support the human exploration of the Red Planet.

“So the STPI is right. Using NASA’s current plan we will not reach Mars in 2033 or any other time. But there is a clear alternative, which is the Mars Direct plan, or plans like it, which use the upper stage of a heavy lift rocket to throw necessary payloads on direct trajectories to Mars, with return methane/oxygen propellant produced in advance of the crew’s arrival from Martian water and CO2. So no lunar orbit Gateways or advanced propulsion spaceships are needed at all. If NASA is serious about sending humans to Mars, it needs to adopt such a practical plan.

“Engineering is the art of making the impossible possible.

“The question is fundamentally this; Will NASA have a purpose-driven plan or a vendor-driven plan? A purpose-driven plan spends money to do things. A vendor-driven plan does things in order to spend money. If we allow NASA to remain in its vendor-driven mode, not only will we not reach Mars by 2033, it is doubtful we will even return to the Moon by that time. But if we insist that our space program be purpose-driven, we can reach the Moon by 2024 and Mars before the end of the decade.”

“Such is the choice before us.”