Getting to the Moon is an expensive proposition, especially if you're getting there with the Space Launch System (SLS). NASA's new megarocket is designed to send the Orion capsule on its way to the Moon. Since it's going there anyway, NASA included a secondary payload adapter to bring some satellites along. The ride-along CubeSats from Artemis I didn't perform very well, but NASA is now working on a larger adapter that will house more capable satellites.
At the recent Annual Conference on Small Satellites, David Hitt from Jacobs Space Exploration Group noted that the 6U CubeSats mounted in Artemis I (above) were considered large when chosen. Still, now teams are looking toward bigger designs. A 6U cube sat measures 10 by 20 by 30 centimeters, roughly the size of a large shoebox. However, SLS delays dragged on for years, and aerospace firms are now more invested in larger CubeSat formats, and that's probably a good thing.
Artemis I carried 10 CubeSats into space—it had room for 13, but three satellites were not ready for the launch. Of those 10, only half of them managed even partial mission success. For example, BioSentinel was supposed to be the first biological experiment in deep space. The cells never grew, but the spacecraft did send back data on radiation around the Moon. The LunaH-Map CubeSat was supposed to look for water ice at the poles, but a propulsion failure kept it from maneuvering there. It did manage to test a new neutron spectrometer, earning it partial credit.
As for the failed satellites, most engineers place the blame on communication. These small, low-power spacecraft were designed to operate in low-Earth orbit, and refitting them for deep space is still a new idea. NASA had modest success with the MarCO CubeSats that rode along with the Perseverance rover to Mars, but that may be the exception rather than the rule. Hitt says that the redesigned adapter connects just behind the Orion service module and will support considerably larger satellites. We don't know how big yet, but it could be 12U (20 x 20 x 32 cm) or even 27U (34 x 35 x 36 cm). These larger CubeSats could carry more instruments and more reliable propulsion and communication systems.
It will be a while before the new adapter flies, though. NASA plans to add this capability to the SLS Block 1B, the next evolution of the SLS with improved payload capacity. That design is slated to go into production for Artemis IV, which is currently scheduled for a 2028 launch. However, it would not be shocking if Artemis launches continued to slip. It may be the next decade before we see SLS carry larger CubeSats to the Moon. Both Artemis II and III will have the capacity to carry smaller CubeSats into space, but the orbit of Artemis II would cause them to swing back toward Earth in mere hours. NASA may choose Artemis III secondary payloads as soon as this year.
