Revisiting SpaceX “Red Dragon” Mars Sample Return

2022?
Image Credit SpaceX

When SpaceX first introduced a version of its Dragon capsule with propulsive capability, one early image released by the company depicted the spacecraft landing on a dusty red surface which looked suspiciously like Mars.

That image, and more than a few comments regarding Dragon’s capabilities by company founder and CEO Elon Musk served as a starting point for any number of proposals seeking to take advantage of not only the Dragon, but also the Falcon Heavy launch vehicle which Musk noted could sent it around the Moon or even on a sample return trip to Mars.

The latter concept came to be known as the “Red Dragon” mission, one which was formalized in a paper by engineers at NASA’s Ames Research Center in 2013, and the subject of a NASA Future in Space Operations presentation by ARS’s  Andy Gonzales, Senior Systems Engineer and Larry Lemke (ret) on Wednesday.

The basic concept is surprisingly straight forward. Beginning in 2022, a Falcon Heavy would loft a heavily modified Dragon spacecraft en-route to Mars.

Inside the stripped down pressure hull of the “Red Dragon” and essentially jutting out of the absent nose hatch would be a Mars Ascent Vehicle topped by an even smaller Earth Return Vehicle capable of transporting 500 grams of the Red Planet back to the vicinity of Earth.

The samples themselves would be those gathered by the Mars 2020 mission rover, which is an updated version of the current Curiosity rover now traversing the Gale Crater. Cached samples would be lifted from the 2020 rover by a small robotic arm attached to the Red Dragon, which would then place the samples in the secured compartment of the upper stage ERV. And just in case the Rover was unable to make the appointed rendezvous, the arm would instead be used to dig an alternate sample from just under the lander itself.

Once it was time to depart, the MAV would fire its hypergolic engines, with the exhaust flames ducted through a hatch opening in the center of the Dragon’s heat shield, in a design borrowed from the Space Shuttle’s landing gear doors.

After reaching Martian orbit, the ERV would fire, sending the sample on its way to a rendezvous with a dedicated atmospheric entry vehicle, either another Dragon, or perhaps an Orion, for sample transfer and and return to Earth in a secondary sealed container secured in the top of capsule near the hatch opening.

The lunar (or high Earth orbit) rendezvous is necessitated by the fact that while the SpaceX Dragon is capable of landing on Mars carrying approximately two tons of cargo, which in this case takes the form of a 1300 kg return stack including all the necessary propellant, the available mission mass does not leave room for a direct entry vehicle encompassing both a credible payload and all of the safety measures required to meet planetary protection standards.

A 5 kilogram Mars Sample return would not just meet a significant scientific objective, it would in fact comprise the single most important such objective outlined in the 2013 Decadal Survey for Planetary Science.

It is made possible by the Dragon’s unique architecture, which includes a fairly light weight pressure shell combined with an integral propulsive capability provided by the SuperDraco thrusters, which in this case would be augmented by two additional propellant tanks secured inside the Dragon. Combined with the blunt heat PICA-X heat shield, NASA analysis indicates it should easily of capable of bringing the Dragon and its cargo through hypersonic, supersonic and subsonic regimes which comprise Entry, Descent and Landing with a propulsive burn lasting only 9 seconds.

The Red Dragon MSR concept is for now, just that, a concept. Furthermore, the authors are quick to point out that it has been prepared based on publicly available information, without direct participation from SpaceX.

Still, it is one which has been prepared through the course of extensive analysis using several well accepted NASA tools, leaving little doubt that it is achievable. While cost estimates are one of the factors awaiting further analysis, the basic costs of the Falcon Heavy and unmodified Dragon spacecraft are well known, presenting a comparative bargain for achieving a goal which had stood as the Holy Grail for planetary exploration for nearly forty years.

It is more than that however; the same propulsive landing capability which could bring a Red Dragon down at the Mars elevation equivalent of sea level, could also deliver smaller payloads to elevations which are currently inaccessible with parachute based systems. Provided SpaceX can demonstrate the capsule’s resilience in the higher radiation environment it would encounter beyond low Earth orbit, as well as upgrade the short lived solar solar array, robotic Dragons could offer a low cost exploration platform suitable not just for Mars, but for much of the inner solar system.

Will it come to pass? Possibly, but there are some powerful forces arrayed against it.  It is a sad thing to say, but one suspects that within certain NASA quarters, and certainly within some contractor offices, that it would be considered preferable to wait another 40 years, or perhaps even forever, than to achieve a Mars sample return in the next 10 years using SpaceX hardware out of fear it would pose a mortal threat to the Space Launch System and Orion architecture which is being promoted as the preferred ticket for NASA’s “Journey to Mars.”

Overcoming that obstacle may make the fiery challenges of Entry, Descent and Landing look like a walk in the park.