New Horizons to shut heliophysics instruments

NASA’s New Horizons mission is facing a new funding fight, this time over the spacecraft’s heliophysics work rather than its planetary science legacy. A public petition circulated this week says the mission plans to shut down its two key heliophysics instruments starting in fiscal year 2027 unless NASA finds about $2 million a year to keep collecting and downlinking the data. The instruments at issue are SWAP and PEPSSI, which measure the solar wind, pickup ions and energetic particles in the outer heliosphere. NASA said in 2023 that New Horizons would shift its emphasis beginning in fiscal 2025 toward “unique heliophysics data” gathered during a low-activity extended mission. ### Which instruments are at risk? SWAP and PEPSSI are the two plasma and particle instruments on New Horizons, according to the spacecraft’s Johns Hopkins Applied Physics Laboratory mission page. The petition says those instruments are making “historically unique” measurements of interstellar hydrogen and helium pickup ions that Voyager was not equipped to make. A 2023 APL technical digest article by members of the New Horizons team said the same instruments were planned to study the evolution of the solar wind, pickup ions, energetic particles and galactic cosmic rays in the outer heliosphere. (nasawatch.com) ### Why is a Pluto mission doing heliophysics at all? NASA said on September 29, 2023 that New Horizons would continue exploring the outer solar system under an updated plan that, beginning in fiscal 2025, would focus on gathering heliophysics data. The agency said at the time that the spacecraft had a “unique position” in the solar system and that the extended mission would be primarily funded by NASA’s Planetary Science Division and jointly managed by the Heliophysics and Planetary Science divisions. (jhuapl.edu) NASA also said then that it expected New Horizons to exit the Kuiper Belt in 2028 through 2029. Nicola Fox, NASA’s associate administrator for the Science Mission Directorate, said in that 2023 statement that New Horizons had a “unique position in our solar system to answer important questions about our heliosphere.” That earlier decision is central to the current dispute because the petition argues that continued heliophysics measurements are now threatened unless NASA’s Heliophysics Division funds the data collection and downlink. (nasa.gov) ### What is the $2 million fight actually about? The petition says the shortfall is tied to continued operations and downlink of heliophysics data, not to the survival of the spacecraft itself. NASA Watch, which reposted the appeal on September 1, said New Horizons planned to shut down both heliophysics instruments “for a lack of $2 million per year starting in FY 2027.” The petition is addressed to Fox, Heliophysics Division Director Joseph Westlake and Planetary Science Division Director Louise Prockter. (nasa.gov) NASA’s budgets page shows the agency has published a fiscal year 2027 budget request, but the materials surfaced here do not specify a line item for continued New Horizons heliophysics downlink. The petition frames the issue as a division-level funding decision inside NASA’s Science Mission Directorate. ### Why are scientists pressing now? The petition says New Horizons is projected to operate until about 2050, reaching roughly 135 astronomical units from the Sun. (nasawatch.com) It also says the spacecraft is estimated to encounter and cross the heliospheric termination shock sometime from 2027 into the mid-2030s, making the next several years especially important for the two instruments now at risk. Universe Today, citing principal investigator Alan Stern, reported on September 2 that New Horizons could reach the termination shock in the next couple of years and the heliopause in the next decade. (nasa.gov) ### What happens next inside NASA? Fiscal year 2027 begins on October 1, 2026, and the petition says instrument operations are funded only through fiscal 2026. The immediate next step is whether NASA’s Science Mission Directorate, and specifically the offices led by Fox, Westlake and Prockter, finds the roughly $2 million a year the petition seeks for continued SWAP and PEPSSI data collection and downlink. (change.org)