Hitching a Ride to the Moon (and Beyond!)

 Above, a series of ten 6-U cubesats can be seen attached to the ring which interfaces between the top of the Space Launch System (SLS) rocket and the payload fairing. It's not unusual these days for spacecraft to use extra mass allowances for these sorts of ride-along launches. It would be very difficult to arrange a special launch just for those spacecraft, so these larger launches provide a vehicle to considerably increase the science return from a space launch and to provide access to (deep) space to others. Here at PVL, we're very excited about the coming small-space era in Planetary Science!

By Conor Hayes

The launch of Artemis I on November 16, 2022 was a highly-publicized event, and for good reason. It has been 50 years since the last time we left the Moon, and although the first crewed landing of the Artemis program is not expected to take place until 2025, Artemis I is still an exciting step towards our return to the Moon.

Much less well-advertised was the fact that the Orion Multi-Purpose Crew Vehicle was not the only spacecraft riding the SLS rocket to space that night. Accompanying Orion were ten CubeSat microsatellites. The CubeSat standard was established in 1999 and has primarily been used for technology demonstrations and other missions whose higher risks make larger, more expensive satellites challenging to justify. Of course, this means that CubeSats are almost never launched on their own, instead needing to hitch a ride along with some other mission.

The ten CubeSats launched along with Artemis I were all in a 6U configuration, meaning that they each consisted of six CubeSat “units” joined together. A CubeSat unit is a box approximately ten centimetres along each edge with a mass of no more than two kilograms. This extremely small volume means that CubeSats have a very limited ability to propel themselves, so they are typically launched along with a mission that has the same target object. In the case for the Artemis CubeSats, this means that five of the ten microsatellites are aiming for the Moon as well.

So, what were the ten CubeSats that Artemis I carried into space?

ArgoMoon
ArgoMoon is a collaboration between the Italian Space Agency and Argotec, an Italian aerospace engineering company. Its primary mission is to take images of the Interim Cryogenic Propulsion Stage – where all of the CubeSats are stored – and to confirm that the other CubeSats successfully deploy. This mission will demonstrate the ability to use a microsatellite to autonomously inspect and maneuver around another spacecraft. Once deployment of the other CubeSats is complete, ArgoMoon will test the resiliency of its communications equipment in the harsh radiation environment outside of Earth’s magnetic field.

BioSentinel
The BioSentinel CubeSat mission was created by NASA Ames to examine the effects on DNA of long-term exposure to the deep space radiation environment. This is critically important information to have as we prepare for extended missions to the Moon and Mars so that we can develop methods of mitigating DNA damage to reduce the likelihood of astronauts developing various cancers and other threats to their health. BioSentinel will use two different strains of yeast as an analogue for human cells. The health of the yeast cells during the 18 month mission will be assessed by monitoring their growth and metabolic activity and comparing it to the radiation doses measured by sensors onboard the spacecraft. The results will then be compared to three identical copies of the BioSentinel experiment, one of which will be exposed to the low Earth orbit radiation environment onboard the International Space Station.

CuSP
The CubeSat for Solar Particles (CuSP) is a technology demonstration mission developed by the Southwest Research Institute. It contains three science instruments designed to count the number of energetic particles ejected by the Sun, as well as to measure the strength and direction of the interplanetary solar magnetic field. If all goes well, CuSP could justify the creation of a fleet of similar small satellites positioned throughout the Solar System to form a space weather monitoring system. 

EQUULEUS
The EQUilibriUm Lunar-Earth point 6U Spacecraft (EQUULEUS) is one of two Artemis CubeSats provided by the Japan Aerospace Exploration Agency (JAXA). Despite its small size, much science has been packed into it. EQUULEUS carries three science instruments as well as an experimental propulsion system. Two of the instruments are designed to detect the presence of dust and micro-asteroids in the space between Earth and the Moon, while the third will characterize the near-Earth plasma environment. Rather than traditional rocket fuel-powered propulsion, EQUULEUS will use water thrusters to propel itself into a halo orbit at the Earth-Moon L2 Lagrangian point and to fly-by any micro-asteroids that it discovers.

LunaH-Map
The Lunar Polar Hydrogen Mapper (LunaH-Map) was provided by Arizona State University to map water ice at the Moon’s poles. It will use a neutron spectrometer to measure the flux of high-energy neutrons leaving the lunar surface. These neutrons are suppressed by the presence of hydrogen atoms, so areas where LunaH-Map measures fewer neutrons are likely enhanced in hydrogen-bearing molecules like water. This mission will build on results from the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO), building higher-resolution maps thanks to its lower-altitude orbit (5 km for LunaH-Map versus 20 km for LRO). Unfortunately, the satellite experienced a problem with its propulsion system shortly after deployment, meaning that it was unable to insert itself into lunar orbit. However, there are still several months left to diagnose the problem before its current trajectory will make the mission unrecoverable. If the LunaH-Map is able to diagnose and fix the problem and get the spacecraft into orbit, the mission is planned to last for 96 days, after which it will be launched into a polar crater. 

Lunar IceCube
As its name suggests, Lunar IceCube is another mission to search for ice on the Moon, developed by Morehead State University in collaboration with the Busek Company, the Catholic University of America, and NASA Goddard. It will hunt for water ice and other volatile molecules at the Moon’s poles from a 100 km orbit using an infrared spectrometer. 

LunIR
LunIR (formerly known as SkyFire), designed by Lockheed Martin Space, is another lunar mapping mission. Its primary mission objective is to test a low-cost thermal imager that could be used to characterize future landing sites on the Moon and Mars. It will also test the use of an electrospray thruster, in which electrically-charged liquid is expelled to provide thrust, for small orbital adjustments. The LunIR team have not provided updates on the spacecraft’s status post-launch, so it is currently unclear whether or not it is operating as expected. 

NEA Scout
The Near-Earth Asteroid Scout (NEA Scout) is a NASA mission that will use a solar sail to propel itself to 2020 GE, a near-Earth asteroid approximately 18 metres across. Because it is extremely difficult to identify and track objects of this size, not much is known about them, leaving a critical gap in planetary protection plans. This mission carries a single instrument – a camera that will be used to take high-resolution imagery of 2020 GE. Unfortunately, NEA Scout failed to make contact with the Deep Space Network after deployment, so the team is currently attempting to recover the spacecraft.

OMOTENASHI
The Outstanding MOon exploration TEchnologies demonstrated by NAno Semi-Hard Impactor (OMOTENASHI; some very creative acronym work!) is the second of JAXA’s contributions to the Artemis I CubeSat collection. It was designed to be a semi-hard lunar lander, using a combination of rockets and airbags to impact the lunar surface at 20–30 m/s. It would then use an onboard radiation detector to study the radiation environment at the surface. Shortly after deployment, communication with OMOTENASHI was lost. After five days of recovery efforts, the team concluded that the spacecraft’s solar panels had failed to find the Sun, leading to an unrecoverable shutdown of the spacecraft following battery depletion.

Team Miles
The final of the ten CubeSats is Team Miles, a technology demonstration mission by Fluid and Reason, LLC. Team Miles was developed to test new propulsion and communications technologies. It will fly past the Moon towards Mars, with a goal to travel at least four million km and possibly up to 96 million km.
These will certainly not be the last CubeSats launched towards the Moon as we enter the Artemis era of lunar exploration. Indeed, there are already three more prepared for launch that just missed the Artemis I integration deadline: Cislunar Explorers, Earth Escape Explorer, and Lunar Flashlight. Although they may not nearly be as flashy as larger missions like the main Artemis flights, the proliferation of microsatellites has provided excellent opportunities for groups with less available funding to get good science done without having to compete for space onboard a more expensive mission, making off-Earth research more accessible for everyone.