Psyche (spacecraft)

Psyche 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 manages the project.
The spacecraft will not land on the asteroid, but will orbit it 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's 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 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.

Target

16 Psyche is the heaviest known M-type asteroid with a mean diameter of, 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 in collaboration with SSL 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 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

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:

Understand a previously unexplored building block of planet formation: iron cores.
Look inside terrestrial planets, including Earth, by directly examining the interior of a differentiated body, which otherwise could not be seen.
Explore a new type of world, made of metal.

The science questions this mission aims to address are:

Is 16 Psyche the stripped core of a differentiated planetesimal, or was it formed as an iron-rich body? What were the building blocks of planets? Did planetesimals that formed close to the Sun have very different bulk compositions?
If 16 Psyche was stripped of its mantle, when and how did that occur?
If 16 Psyche was once molten, did it solidify from the inside out, or the outside in?
Did 16 Psyche produce a magnetic dynamo as it cooled?
What are the major alloy elements that coexist in the iron metal of the core?
What are the key characteristics of the geologic surface and global topography? Does 16 Psyche look radically different from known stony and icy bodies?
How do craters on a metal body differ from those in rock or ice?
Instruments

Payloads installed on Psyche are:

Instrument	Function	Team
The Psyche Multispectral Imager	It will provide high-resolution images using filters to discriminate between 16 Psyche's metallic and silicate constituents. The instrument consists of a pair of identical cameras designed to acquire geologic, compositional, and topographic data. The purpose of the second camera is to provide redundancy for mission-critical optical navigation.	Arizona State University
Psyche Gamma-ray and Neutron Spectrometer	It will detect, measure, and map 16 Psyche's elemental composition. The instrument is mounted on a boom to distance the sensors from background radiation created by energetic particles interacting with the spacecraft and to provide an unobstructed field of view.	Applied Physics Laboratory at Johns Hopkins University.
Psyche Magnetometer	The Psyche Magnetometer is designed to detect and measure the remanent magnetic field of the asteroid. It is composed of two identical high-sensitivity magnetic field sensors located at the middle and outer end of a boom.	Massachusetts Institute of Technology and Technical University of Denmark
Deep Space Optical Communications	The Psyche mission will test a sophisticated new laser communication technology that encodes data in infrared-photons to communicate with a probe in deep space from Earth. Using shorter wavelengths allows the spacecraft to transmit more data in a given amount of time.	Jet Propulsion Laboratory

Spacecraft

The spacecraft uses the Space Systems/Loral 1300 bus platform. JPL added the command and data handling and telecom subsystems and all flight software.

Propulsion

SPT-140	Parameter/units
Type	Hall-effect thruster
Power	Max: 4.5 kW Min: 900 watts
Specific impulse	1800 seconds
Thrust	280 mN
Thruster mass	8.5 kg
Propellant mass	922 kg of xenon
Total impulse	8.2 MN·s

The spacecraft uses ion propulsion. It has four SPT-140 engines, which are Hall-effect thrusters using solar electric propulsion, where electricity generated from solar panels is transmitted to an electric, rather than chemically powered, rocket engine. The thruster is nominally rated at 4.5 kW operating power, but it will also operate for long durations at about 900 watts. Psyche is the first interplanetary mission to use Hall-effect thrusters, although not the first to use electric thrusters in general.
The SPT-140 is a production line commercial propulsion system that was invented in the USSR by OKB Fakel and developed by NASA's Glenn Research Center, Space Systems/Loral, and Pratt & Whitney since the late 1980s. The SPT-140 thruster was first tested in the US at the Plasmadynamics and Electric Propulsion Laboratory in 1997, and later as a 3.5 kW unit in 2002 as part of the Air Force Integrated High Payoff Rocket Propulsion Technology program.
Using solar electric thrusters will allow the spacecraft to arrive at 16 Psyche much faster, while consuming less than 10% of the propellant it would need using conventional chemical propulsion.