Psyche (spacecraft)


Psyche is a planned orbiter mission that will explore the origin of planetary cores by studying the metallic asteroid 16 Psyche. Lindy Elkins-Tanton of Arizona State University is the principal investigator who proposed this mission for NASA's Discovery Program. NASA's Jet Propulsion Laboratory will manage the project.
16 Psyche is the heaviest known M-type asteroid, and is thought to be the exposed iron core of a protoplanet, the remnant of a violent collision with another object that stripped off its outer crust. Radar observations of the asteroid from Earth indicate an iron–nickel composition. On 4 January 2017, the Psyche mission was selected for NASA's Discovery #14 mission.

History

Psyche was submitted as part of a call for proposals for NASA's Discovery Program that closed in February 2015. It was shortlisted on 30 September 2015, as one of five finalists and awarded US$3 million for further concept development. One aspect of selection was enduring the "site visit" in which about 30 NASA personnel come and interview, inspect, and question the proposers and their plan.
On 4 January 2017, Lucy and Psyche were selected for the 13th and 14th Discovery missions, respectively, with launch for Psyche set for 2023. In May 2017, the launch date was moved up to target a more efficient trajectory, launching in July 2022 aboard a SpaceX Falcon Heavy launch vehicle and arriving on 31 January 2026 with a Mars gravity assist on 23 May 2023.

Mission overview

The Psyche spacecraft will use solar electric propulsion, and the scientific payload will be an imager, a magnetometer, and a gamma-ray spectrometer.
Data shows asteroid 16 Psyche to have a diameter of about. Scientists think that 16 Psyche could be the exposed core of an early planet that could have been as large as Mars and lost its surface in a series of violent collisions.
The mission will launch in August 2022 and arrive in four years to perform 21 months of science. The spacecraft will be built by NASA JPL in collaboration with SSL and Arizona State University.
It has been proposed that the rocket may 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 2020, it was announced that the Falcon Heavy carrying Psyche will include two smallsat secondary payloads to study the Martian atmosphere and binary asteroids, named EscaPADE and Janus respectively.

Science goals and objectives

was 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 will 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:
The science objectives are:
The science questions this mission will address are:
Psyche will fly a payload of, consisting of four scientific instruments:
The spacecraft will also test an experimental laser communication technology called Deep Space Optical Communications. It is hoped that the device will be able to increase spacecraft communications performance and efficiency by 10 to 100 times over conventional means. The laser beams from the spacecraft will be received by a ground telescope at Palomar Observatory in California.

Propulsion

SPT-140Parameter/units
TypeHall-effect thruster
PowerMax: 4.5 kW
Min: 900 watts
Solar array performance:
At Earth: 20 kW
At : 2.3 kW
Specific impulse 1800 seconds
Total impulse8.2 MN·s
Thrust280 mN
Thruster mass8.5 kg
Propellant mass≈ 425 kg of xenon

This mission will use the model SPT-140 engine, a Hall-effect thruster utilizing 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.
The SPT-140 is a production line commercial propulsion system that was invented in Russia 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 US 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 only 10% of the propellant it would need using conventional chemical propulsion.
Electricity will be generated by bilateral solar panels in an X-shaped configuration, with five panels on each side. Prior to the mission being moved forward with a new trajectory, the panels were to be arranged in straight lines, with only four panels on each side of the spacecraft.

Operations

Launch and trajectory

The launch is planned for August 2022 on a Falcon Heavy vehicle. The cost of the launch, including secondary payloads, is US$117 million. Psyche will be launched on a trajectory that will perform a gravity assist maneuver past Mars on 23 May 2023, toward the asteroid belt, and intercept the asteroid Psyche.

Orbit regimes

Psyche will encounter 16 Psyche asteroid and enter orbit on 31 January 2026. The spacecraft would orbit at decreasing altitudes or regimes. Its first regime,, will see the spacecraft enter a orbit for magnetic field characterization and preliminary mapping for a duration of 56 days. It will then descend to, set at altitude for 76 days, for topography and magnetic field characterization. It will then descend to, at altitude for 100 days to perform gravity investigations and continue magnetic field observations. Finally, the orbiter will enter, set at to determine the chemical composition of the surface using its gamma-ray and neutron spectrometers. It will also acquire continued imaging, gravity, and magnetic field mapping. The mission is planned to orbit the asteroid for at least 21 months.

Ground stations for laser link

The laser beams from the spacecraft will be received by a ground telescope at Palomar Observatory in California.Laser beams to the spacecraft will be sent from a smaller telescope at Table Mtn, CA.