Psyche ( SY-kee) is a NASA Discovery Program space mission launched on October 13, 2023, to explore the origin of planetary cores by orbiting and studying the metallic asteroid 16 Psyche beginning in 2029. NASA's Jet Propulsion Laboratory (JPL) manages the project. The spacecraft will orbit the asteroid from August 5, 2029, to October 31, 2031, spending 817 days in orbit. Psyche uses solar-powered Hall-effect thrusters for propulsion and orbital maneuvering, the first interplanetary spacecraft to use that technology. It is also the first mission to use laser optical communications beyond the Earth-Moon system.
History
The proposal for the Psyche mission was submitted by Lindy Elkins-Tanton, a principal investigator at Arizona State University, as part of a call for proposals for NASA's Discovery Program missions 13 and 14 that closed in February 2015. It was shortlisted on September 30, 2015, as one of five finalists, and awarded US$3 million for further concept development. On January 4, 2017, Psyche was selected for the 14th Discovery mission, with launch set for 2023. In May 2017, the launch date was moved up to target a more efficient trajectory, to July 2022 aboard a SpaceX Falcon Heavy launch vehicle with a January 31, 2026 arrival, following a Mars gravity assist on May 23, 2023. In June 2022 NASA found that the late delivery of the testing equipment and Guidance, Navigation, and Control (GNC) flight software for the Psyche spacecraft did not give them enough time to complete the required testing, and decided to delay the launch, with future windows available in 2023 and 2024 to rendezvous with the asteroid in 2029 and 2030, respectively. On October 28, 2022, NASA announced that Psyche was targeting a launch period opening on October 10, 2023, which would correspond with an arrival at the asteroid in August 2029. An independent review of the delays at JPL reported in November 2022 found understaffing, insufficient planning, and communications issues among engineers and with management. The VERITAS Venus mission was delayed to free up staff to focus on Psyche. On April 18, 2023, JPL's mission page for Psyche was updated to reflect a new launch date of October 5, 2023. On September 28, 2023, the launch was again delayed to no earlier than October 12, 2023, due to an unspecified issue with the spacecraft. After one additional delay due to bad weather, Psyche was launched successfully on October 13, 2023. An update in May 2024 reported the spacecraft was in good health and on track to complete its mission on the planned timeline along with commencing fire of its xenon thrusters. In April 2025, Psyche experienced an unexpected drop in the pressure of its xenon propulsion system. The spacecraft paused its thrusting while the problem was under investigation and its system engineers considered resorting to the spacecraft's backup redundancy fuel line in order to continue the probe's thrust operation. Following a switch to the backup fuel line in May, full thruster operation resumed on June 16, 2025.
On May 15, 2026, Psyche successfully flew by Mars as part of a gravity-assist maneuver that adjusted its orbital tilt around the Sun, allowing the probe and its path to align with the orbital plane of asteroid Psyche. The probe flew as close as 4,500 km (2,800 mi) above the surface of the Red Planet. The probe used its multispectral imager instrument to image the planet. Because Psyche approached Mars at a high phase angle, the planet appeared as a thin crescent before the close flyby, illuminated by sunlight reflected from its surface. Images taken by the spacecraft’s multispectral cameras showed the crescent appearing brighter and stretching farther around Mars than expected because sunlight was strongly scattered by the planet’s dusty atmosphere.
Target
16 Psyche is the heaviest known M-type asteroid with a mean diameter of 220 kilometres (140 mi), and may be an exposed iron core of a protoplanet, the remnant of a violent collision with another object that stripped off its mantle and crust. Recent studies show that it is "a mixed metal and silicate world". Another study considers it to be either a metal core of a protoplanet or "a differentiated world with a regolith composition ... peppered with localized regions of high metal concentrations". Radar observations of the asteroid from Earth indicate an iron–nickel composition. The historical asteroid symbol for Psyche, a butterfly's wing topped by a star (), may have influenced the mission insignia.
Mission overview The Psyche spacecraft is designed with solar electric propulsion, and the scientific payload includes a multispectral imager, a magnetometer, and a gamma-ray spectrometer. The mission is designed to perform 21 months of science. The spacecraft was built by NASA Jet Propulsion Laboratory (JPL) in collaboration with SSL (formerly Space Systems/Loral) and Arizona State University. It was proposed that the rocket launch might be shared with a separate mission named Athena, that would perform a single flyby of asteroid 2 Pallas, the third-largest asteroid in the Solar System. In May 2020, it was announced that the Falcon Heavy carrying Psyche would include two smallsat secondary payloads to study the Martian atmosphere and binary asteroids, named EscaPADE (Escape and Plasma Acceleration and Dynamics Explorers) and Janus respectively, but in September 2020, the EscaPADE Mars atmosphere probe was removed from the plan. Janus was later removed from the Psyche mission as well on November 18, 2022, after an assessment determined that it would not be on the required trajectory to meet its science requirements as a result of Psyche's new launch period.
Science goals and objectives
Differentiation is a fundamental process in shaping many asteroids and all terrestrial planets, and direct exploration of a core could greatly enhance understanding of this process. The Psyche mission aims to characterize 16 Psyche's geology, shape, elemental composition, magnetic field, and mass distribution. It is expected that this mission will increase the understanding of planetary formation and interiors.
Specifically, the science goals for the mission are:
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