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Through its "Moon to Mars" program, NASA plans to send the first crewed missions to Mars by the end of the next decade. To fulfill this bold vision, the agency is investigating advanced technologies through numerous programs. This includes advanced propulsion technologies that will reduce transit times to Mars, thereby limiting astronaut exposure to microgravity and cosmic radiation. Other technologies under consideration include methods for waste elimination, water reclamation, crew health and safety, and resource self-sufficiency.

NASA is also working to evolve key technologies that will enable low-cost exploration missions to Mars and throughout the solar system. This includes what is considered to be the most important technology: sub-kilowatt electric propulsion systems for small spacecraft—500 kg (1100 lbs) or less. In a submitted to the 56th Lunar and Planetary Science Conference (), a team of NASA researchers proposes a new initiative: the Commercial Hall Propulsion for Mars Payload Services (CHAMPS).

The study was conducted by NASA researchers Gabriel F. Benavides, Steven R. Oleson, and Alain S.J. Khayat. Benavides is an in-space electric propulsion engineer at NASA Glenn Research Center (GRC), while Alain S.J. Khayat is a Research Scientist at NASA's Goddard Space Flight Center. Steven R. Oleson is the leader of the Compact Fission Reactor Design Team at Los Alamos National Laboratory and the lead of the Compass team at NASA GRC. This collaborative engineering team performs integrated vehicle systems analyses.

A technology gap

As they indicate, their work is based on previous work like the Planetary Science Deep Space SmallSat Studies (PSDS3) and the Small, Innovative Missions for PLanetary Exploration (SIMPLEx) program. These studies established the importance of low-power, high-throughput electrostatic Hall Effect Thrusters (HET) with optimized magnetic shielding. These propulsion systems rely on solar power (or another energy source to ionize an inert gas propellant (like xenon), which is channeled by magnetic fields to generate thrust.

Per the Artemis Program, these systems will propel the first two elements of Lunar Gateway—the Power and Propulsion Element (PPE) and the Habitation and Logistics Outpost (HALO)—to their proposed orbit around the moon. This mission, currently scheduled for 2027, will see both elements launched by a Falcon Heavy from Earth to a lunar orbit. Once there, the PPE and HALO modules will rely on their high-power solar-electric propulsion (SEP) systems to establish a near-rectilinear halo orbit (NRHO).

Unfortunately, this area has had a technology gap, so NASA launched the Small Spacecraft Electric Propulsion (SSEP) project in 2017. This program aims to develop miniaturized versions of NASA's most advanced high-power solar-electric propulsion (SEP) systems. NASA's H71M is the current example of a miniaturized high-performance SEP. With a predicted propellant throughput of more than 140 kg (310 lbs), this system generates enough power to propel a 450 kg (990 lbs) spacecraft.

NASA began collaborating and licensing the H71M with commercial partners to ensure the system's availability for future small-spacecraft missions. This led Oleson and the Compass team to develop their CHAMPS concept for potential missions to Mars. This study envisions spacecraft using a commercial version of the H71M—the NGHT-1X system developed by Northrop Grumman. These missions would rely on more frequent and lower-cost launch opportunities rather than a direct-to-Mars transfer orbit.

Mission concept

One of the biggest challenges for mounting lower-cost science missions with small spacecraft is identifying and holding to a particular Mars launch opportunity. Launching as a primary payload is potentially expensive, while launching as a secondary payload can cause complications since the needs of the primary payload drive the launch date and trajectory. What's more, pivoting to an alternative launch date is not always an option. The CHAMPS architecture addresses this by opting for a secondary payload launch with a CLPS mission.

These missions are expected to regularly deliver payloads to the moon in the coming years. The launch trajectory is well understood, and there are likely to be many alternative launch opportunities. The mission would perform instrument checks by observing the moon while conducting a gravitational assist maneuver to gain velocity. This maneuver will allow the mission to temporarily insert itself into an NHRO around the moon until a favorable Earth-Mars alignment occurs.

The first low-thrust maneuver will last for about three months, followed by a four-month cruise phase and another seven-month low-thrust maneuver. Once it reaches Mars, the spacecraft will establish an orbit 15 km (9.32 mi) above the surface, where it will have complete equatorial coverage every five sols (5.137 Earth days). In the meantime, it will fulfill secondary science objectives by studying Deimos, the smaller of Mars' two moons. After two years, the spacecraft will ascend to an aerosychronous orbit—17 km (10.5 mi) above the surface.

This will enable continuous coverage of the atmosphere above critical surface features while acting as a data relay for surface missions.

Instruments and objectives

The CHAMPS mission will carry out multiple scientific studies using various instruments. Per their paper, this will include a Visible/UV imager, like the Mars Color Imager (MARCI) used by the Mars Climate Orbiter (MCO) and Mars Reconnaissance Orbiter (MRO). It will also have a thermal infrared (TIR) radiometer comparable to the mini-Mars Climate Sounder (MCS) used by the Mars Reconnaissance Orbiter (MRO), and a near-infrared (NIR) spectrometer like the Argus instrument used to conduct atmospheric studies here on Earth.

Using these instruments, the CHAMPS mission will measure the 3D structure of the atmosphere to determine its pressure, temperature, aerosol distribution, water vapor, and ozone content. It will also monitor the behavior and evolution of Martian dust and water ice clouds to learn more about the planet's weather patterns and seasonal dust storms. Third, it will measure the plasma conditions and magnetic field structure around Mars and how it interacts with extreme ultraviolet (EUV) radiation from the sun.

These studies will allow scientists to investigate key science questions about the Martian climate, including the interaction and transport of volatiles between the surface and atmosphere, how the lower/middle atmosphere responds to solar heating regionally and globally and a daily and seasonal basis, how coupling occurs between the different levels of the atmosphere, and how space weather influences the atmosphere.

The team also points out that their proposal is consistent with Initiative 1 of NASA's Mars Exploration Program (MEP) plan, which states:

"Establish a regular cadence of science-driven, lower-cost mission opportunities as a new element of the MEP portfolio to provide rapid and flexible response to discoveries, to address the breadth of outstanding Mars questions, and to enable increased participation by the diverse Mars science community."