The next great adventures for human space exploration have been touted as missions to asteroids and to the Martian surface. But a new presentation by NASA has revealed a line of thought within the agency regarding a potential human or robotic mission to Mars’ largest moon Phobos as the key precursor mission to the Red Planet.
A phased approach:
Part of NASA’s drive for human exploration beyond the confines of Earth’s gravitational sphere involves a phased approach instead of an outright push to Mars.
While criticized by some as ineffective and an inappropriate use of funding, a phased approach to an eventual mission to the Martian surface would allow NASA time to develop and test – in multiple settings and modes – the needed technologies for a Martian surface mission over the course of a couple decades rather than in a relatively short period of time with limited testing opportunities.
Despite the criticism, this phased approach is already underway with the development of the new Space Launch System (SLS) rocket as well as the Orion service module and capsule – which made its maiden test flight on 5 December 2014.
Moreover, another controversially important part of this phased development is the proposed upcoming Asteroid Redirect Mission (ARM) in the 2020s.
The ARM mission would see the in-flight test of a Solar Electric Power (SEP) thruster system to propel a spacecraft to a Near Earth Asteroid (NEA), land on that NEA, collect a 4m boulder from the NEA’s surface, demonstrate at least one planetary defense procedure, and then fly the collected boulder back to Earth and place it into a stable lunar orbit.
Robotic and potential human exploration of the newly redirected asteroid boulder (along with missions to the Earth-moon Lagrangian points) would then provide NASA with additional opportunities to develop what are known as Cis Lunar (the area of space extending from just above Earth’s atmosphere to just beyond the orbit of the moon) technologies that will help with the push toward the Martian system.
However, it now appears that NASA is at least considering a potential precursor mission to the surface of Phobos before pressing forward with human surface operations on Mars.
Why go to Phobos first?
Precursor missions to the surface of Phobos prior to undertaking human Martian surface operations would allow for a continuation in the phased approach of development, implementation, and in-situ testing/experience of the necessary hardware for an eventual Mars surface mission.
In fact, Phobos was at the center of NASA’s “Flexible Path” approach that was set to become a front-runner in the Agency’s direction after the Constellation Program (CxP) faltered in the face of criticism at the Augustine Committee.
“A human Mars Orbit/Phobos Mission represents an intermediate step between human exploration missions in near-Earth space and human missions to explore the surface of Mars,” noted the expansive section on the manned missions to Mars/Phobos in the expansive – yet unpublished – presentation (available to download on L2).
However, the Flexible Path approach required a massive campaign that would have been – and still is – unpalatable for SLS, based on flight rate alone.
The 2009 overview called for several Mars Transport Vehicles (Cargo and Crew) to be assembled in Low Earth Orbit before heading off to the vicinity of Mars – via a Venus flyby – requiring up to 15 launches of a Heavy Lift Launch Vehicle (HLV).
“Assuming hydrogen-oxygen in-space propulsion, the number of HLV launches varies between 10 and 15,” added the overview. “Once all of the in-space propulsive stages are assembled in LEO, the crew is launched via Orion and the crew departs for Mars.”
That was 2009.
Currently, NASA’s plans for Mars remain under evaluation with the internal Design Reference Mission (DRM) process.
Nonetheless, a large amount of work is now beginning to take place via the Human Architecture Team (HAT) evaluations, laying the foundations on the huge challenges associated with sending humans to Mars – and returning them safely.
The specific roadmap is still some years away. However, the likelihood of “Phobos First” continues to be referenced in NASA documentation.
The continuing thread surrounding a Phobos mission centers on aiding the development and testing of the technologies needed for Mars surface missions.
Such technologies and hardware include the Phobos Surface Habitat/Landing System, the Phobos Exploration Vehicle (PEV), the PEV-derived Taxi, and exploration suit ports built with exploration environment and atmospheric considerations.
Importantly, these Phobos vehicles and habitats would be designed for use on Mars as well.
Thus, a majority of all Phobos architecture, with the sole exception of the Phobos surface mobility systems – which would be specifically designed for Phobos’ extremely low gravity environment – would subsequently be used for Mars surface missions.
Moreover, the proposed Phobos precursor mission, which assumes the SLS rocket, Orion spacecraft, and exploration suits are already developed, would specifically develop – or continue the development of – seven (7) of the 16 necessary pieces of architecture needed for a Mars surface mission that will either not be developed for or need to be evolved from NEA and Cis Lunar missions.
Among these seven Phobos architectural developments would be the Space Electric Propulsion drive, the Deep Space Habitat, the CPS, the SEV cabin, Phobos Mobility System, suit ports, and hab landing gear.
The hab landing gear would most likely derive from part of the ARM mission architecture base (landing a spacecraft on the surface of an NEA), while several other elements, including SEP, suit ports, microgravity geology, and landing legs, will all derive from Cis Lunar and ARM architecture.
Thus, the Deep Space Habitat, SEV cabin, CPS, and Phobos Mobility System will all be new developments.
However, by developing these seven architectural frameworks for a Phobos-specific mission, only nine remaining Mars surface specific developments would be needed to make the leap from the Phobos mission to a Mars surface mission.
In contrast, should a direct Martian surface mission be chosen, not only will the nine Mars surface specific technologies need to be developed, but the seven Phobos specific requirements will also be needed and have to be funded and developed at the same time.
Thus, the Human Exploration of Phobos and Robotic Precursor Mission presentation notes that “Within an Evolvable Mars Campaign that starts with ARM and Cis Lunar infrastructure, Phobos is a viable human target that is a sensible and relatively affordable step to the Mars system.”
As such, a mission to Phobos would not only return valuable scientific data about the composition of one of Mars’ moons, but would also “enhance and possibly enable the human Mars surface mission” through a phased development and implementation approach.
(Images: Via NASA and L2 – including SLS renders from L2 artist Nathan Koga)
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