PUNCH smallsats
The four PUNCH smallsats, designed to study how the sun’s corona transitions into the solar wind, will fly on the same Falcon 9 as NASA’s SPHEREx astrophysics mission. Credit: SwRI

LOGAN, Utah — Four smallsats designed to study the solar wind will share a ride to space on a Falcon 9 with a NASA astrophysics mission in 2025.

NASA announced Aug. 3 that the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission, a set of four smallsats, will fly as a rideshare on the Falcon 9 launch of the agency’s Spectro-Photometer for the History of the Universe, Epoch of Re-ionization, and Ices Explorer (SPHEREx) mission.

NASA awarded a contract to SpaceX in February 2021 for the Falcon 9 launch for SPHEREx alone, valued at $98.8 million. The agency said it updated the SpaceX contract July 14 to include PUNCH on the same launch but did not disclose any change in contract value.

“It’s great to have a definite launch date and vehicle, and we’re looking forward to working with the SPHEREx team as we ‘carpool’ to orbit,” Craig DeForest, principal investigator for PUNCH at the Southwest Research Institute, said in a statement about the rideshare announcement.

The launch remains scheduled for no earlier than April 2025, the date NASA announced when it awarded SpaceX the launch contract for SPHEREx. PUNCH had previously been planning to launch in October 2023, but the 18-month slip provides “new schedule flexibility to mitigate some schedule constraints due to supply chain challenges,” NASA said.

PUNCH features four satellites, each weighing about 40 kilograms. The satellites will go into a sun-synchronous orbit along the terminator, providing continuous observations of the sun. The spacecraft carry instruments to study how the solar corona transitions into the solar wind.

SPHEREx itself is a small spacecraft, weighing about 200 kilograms. It carries a wide-field telescope designed to carry out an all-sky survey every six months, collecting spectra of hundreds of millions of stars and galaxies.

The small size of SPHEREx suggested at the time of the award that NASA might add more spacecraft to the launch. The agency has, in recent years, sought to take advantage of excess capacity on launches it procures for science missions to fly additional spacecraft.

While the rideshare approach offers cost savings, it can also create scheduling problems. NASA originally planned to fly a small lunar orbiter mission, Lunar Trailblazer, as a rideshare on the Interstellar Mapping and Acceleration Probe (IMAP) mission. However, while Lunar Trailblazer was expected to be ready for launch as soon as late 2022, IMAP will not be ready for launch until early 2025.

NASA announced in June that it would take Lunar Trailblazer off the IMAP launch and instead launch it as a secondary payload on a commercial lunar mission, the IM-2 lunar lander by Intuitive Machines. IM-2 is expected to launch in 2023.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...