Psyche (spacecraft)

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Psyche
PSYCHE.jpg
An illustration of the Psyche spacecraft
Mission typeAsteroid orbiter
Operator
  • NASA
  • ASU
Website
Mission durationCruise: 3.5 years (planned)
Science: 21 months in orbit
(2026-2027) (planned)
Spacecraft properties
SpacecraftPsyche
ManufacturerMaxar Technologies[1]
Launch mass2,608 kg (5,750 lb) [2]
Dry mass1,648 kg (3,633 lb) [3]
Payload mass30 kg (66 lb)
Power4.5 kW
Start of mission
Launch dateAugust 2022
RocketFalcon Heavy[4]
Launch siteKennedy Space Center, LC-39A
ContractorSpaceX
Flyby of Mars
Closest approach23 May 2023
Distance500 km (310 mi)
16 Psyche orbiter
Orbital insertion31 January 2026
Psyche insignia.svg
Psyche mission patch
← Lucy
VERITAS →
 

Psyche is a planned orbiter mission that will explore the origin of planetary cores by studying the metallic asteroid of the same name.[5] 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 (JPL) 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,[6] 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.[7] On 4 January 2017, the Psyche mission was selected for NASA's Discovery #14 mission.[8]

History[]

Main article: Selection of Discovery Mission 13 and 14

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.[5][9] 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.[10]

On 4 January 2017, Lucy and Psyche were selected for the 13th and 14th Discovery missions, respectively, with launch for Psyche set for 2023.[11] 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.[12]

Mission overview[]

The Psyche spacecraft is designed with solar electric propulsion,[13][14] and the scientific payload is expected to include a multispectral imager, a magnetometer, and a gamma-ray spectrometer.[14][15]

Data shows asteroid 16 Psyche to have a diameter of 222 km (138 mi).[16] 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.[11] Its composition and density match mesosiderite meteorites and it is likely their parent body.[17]

The mission is targeting launch in August 2022[4] and arrive in four years to perform 21 months of science. The spacecraft is scheduled to be built by NASA Jet Propulsion Laboratory (JPL) in collaboration with SSL (formerly Space Systems/Loral) and Arizona State University.[18]

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.[19] 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,[12] but in September 2020, the EscaPADE Mars atmosphere probe was removed from the plan.[20]

Science goals and objectives[]

An illustration depicting the target of NASA's Psyche mission: the metal-rich asteroid Psyche, in the main asteroid belt between Mars and Jupiter.
A 3D model of 16 Psyche based on light curve data.

Differentiation 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 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 objectives are:

  • Determine whether 16 Psyche is a core, or if it is unmelted material.
  • Determine the relative ages of regions of 16 Psyche's surface.
  • Determine whether small metal bodies incorporate the same light elements as are expected in the Earth's high-pressure core.
  • Determine whether 16 Psyche was formed under conditions more oxidizing or more reducing than Earth's core.
  • Characterize 16 Psyche's topography.

The science questions this mission aims to address are:[6]

  • 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[]

Psyche will fly a payload of 30 kg (66 lb),[2] consisting of four scientific instruments:[10]

  • The Multispectral Imager will provide high-resolution images using filters to discriminate between metallic and silicate constituents.
  • The Gamma-ray and Neutron Spectrometer will analyze and map the asteroid's elemental composition.
  • The Magnetometer will measure and map the remnant magnetic field of the asteroid.
  • The X-band Gravity Science Investigation will use the X-band (microwave) radio telecommunications system to measure the asteroid's gravity field and deduce its interior structure.

The spacecraft will also test an experimental laser communication technology called Deep Space Optical Communications (DSOC).[21] It is hoped that the device will be able to increase spacecraft communications performance and efficiency by 10 to 100 times over conventional means.[21][22] The laser beams from the spacecraft will be received by a ground telescope at Palomar Observatory in California.[23]

Propulsion[]

The Psyche's electric propulsion system uses SPT-140 Hall-effect thrusters powered by its solar panels.[13] The photo shows an SPT-140 thruster identical to those that will be used on Psyche undergoing testing at NASA's Jet Propulsion Laboratory.
SPT-140 Parameter/units [24][25]
Type Hall-effect thruster
Power [26] Max: 4.5 kW
Min: 900 watts

Solar array performance:

At Earth: 20 kW
At 16 Psyche: 2.3 kW

Specific impulse (Isp) 1800 seconds
Total impulse 8.2 MN·s
Thrust 280 mN[25]
Thruster mass 8.5 kg
Propellant mass ≈ 425 kg of xenon[25]

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.[13][27][28] The thruster is nominally rated at 4.5 kW operating power,[29] but it will also operate for long durations at about 900 watts.[27] Psyche will be the first mission to use Hall-effect thrusters beyond lunar orbit.[30]

The SPT-140 (SPT stands for Stationary Plasma Thruster) is a production line commercial propulsion system [2] 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.[31][32] The SPT-140 thruster was first tested in U.S. as a 3.5 kW unit in 2002 as part of the Air Force Integrated High Payoff Rocket Propulsion Technology program.[29][2] Using solar electric thrusters will allow the spacecraft to arrive at 16 Psyche (at 3.3 astronomical units) much faster while consuming only 10% of the propellant it would need using conventional chemical propulsion.[citation needed]

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.[33]

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.[4] 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.[34]

Orbit regimes[]

Psyche will encounter 16 Psyche asteroid and enter orbit on 31 January 2026. The spacecraft would orbit at decreasing altitudes or regimes.[30] Its first regime, Orbit A, will see the spacecraft enter a 700 km (430 mi) orbit for magnetic field characterization and preliminary mapping for a duration of 56 days. It will then descend to Orbit B, set at 290 km (180 mi) altitude for 76 days, for topography and magnetic field characterization. It will then descend to Orbit C, at 170 km (110 mi) altitude for 100 days to perform gravity investigations and continue magnetic field observations. Finally, the orbiter will enter Orbit D, set at 85 km (53 mi) 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.[30]

Ground stations for laser link[]

The laser beams from the spacecraft will be received by a ground telescope at Palomar Observatory in California.[23] Laser beams to the spacecraft will be sent from a smaller telescope at JPL Table Mountain Facility.[23]

See also[]

  • DAVINCI, a proposed atmospheric probe to Venus
  • Iron meteorite
  • VERITAS, a proposed Venus orbiter

References[]

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  3. ^ https://www.youtube.com/watch?v=WUEkqnsMDLw
  4. ^ Jump up to: a b c Foust, Jeff (28 February 2020). "Falcon Heavy to launch NASA Psyche asteroid mission". SpaceNews.
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