Discovery

16 Psyche (/ˈsaɪkiː/) is a large asteroid discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852 from Naples and named after the Greek mythological figure Psyche. It is one of the dozen most massive asteroids, containing about 1% of the mass of the asteroid belt, and is over 200 kilometres (120 mi) in diameter. Psyche is thought to be the exposed core of a protoplanet, and is the most massive of the metal-rich M-type asteroids. Its composition and density match mesosiderite meteorites and it is likely their parent body. Psyche is scheduled for space exploration, targeted for January 2026. The prefix “16” signifies that it was the sixteenth minor planet in order of discovery.

Symbol for Representing Psyche 16

Astronomers created icon-like symbols for the first fifteen asteroids to be discovered, as a type of shorthand notation consistent with older notation for the classical planets. Psyche was given an iconic symbol, as were a few other asteroids discovered after 16 Psyche. The symbol , a semicircle topped by a star, represents a butterfly’s wing, the symbol of the soul (psyche is the Greek word for “soul”), and a star. However the iconic symbols for all asteroids were superseded and Psyche’s symbol never came into use. With more than a dozen asteroids discovered, remembering all their individual emblems became increasingly unwieldy, and in 1851, German astronomer “J.F. Encke” suggested using a circled number instead: ⑯. The first new asteroid that was designated in 1852 using this new scheme was 16 Psyche when American astronomer James Ferguson published his observations.

Characteristics

Mass, size and shape

Psyche is massive enough that its gravitational perturbations on other asteroids can be observed, which enables a mass measurement. The values for the mass of (3.38±0.28)×10−11M☉ and the density of 6.98±0.58 g/cm3 obtained from a 2002 analysis by Kuzmanoski and Kovačević, of a close encounter with asteroid (13206) 1997 GC22. The new, high-density estimate suggests that 16 Psyche must be composed mostly of metals. As of 2019, the best mass estimate is (2.41±0.32)×1019 kg, with a derived bulk density of 3.99±0.26 g/cm3. Lightcurve inversion model DAMIT 1806 and occultation chords from two observations of 2010 and 2014. The orbit of Psyche between Mars and Jupiter is near-circular. The first size estimate of Psyche came from IRAS thermal infrared emission observations.

They showed that it had a diameter of about 253 kilometres (157 mi),  although it was likely an overestimate as Psyche was viewed pole-on at that time. Light curve analysis indicates Psyche appears somewhat irregular in shape. There is a pronounced mass deficit near the equator at about 90° longitude comparable to Rheasilvia basin on 4 Vesta. There are also two additional smaller (50–70 km in diameter) crater-like depressions near the south pole. Psyche’s north pole points towards the ecliptic coordinate β = 28°, λ = −6°, with a 4° uncertainty. This gives an axial tilt of 95°. Observations of two multi-chord stellar occultations of 2010 and 2014 allow the matching of light curve inversions DAMIT model 1806 that give an equivalent-volume mean diameter of 216±12 km, and an equivalent surface means diameter of 227±13 km. The density of Psyche derived from these estimates, 3.7±0.6 g/cm³, is consistent with that of other metallic asteroids.

Features

Observations of Psyche with Very Large Telescope’s adaptive optics SPHERE imager revealed two large craters, on the order of 90 km across, which were provisionally named Meroe /ˈmɛroʊiː/ and Panthia /ˈpænθiə/, after the twin witches in the Roman novel Metamorphoses by Apuleius.

Composition and origin of Psyche 16 asteroid

The Bondoc meteorite, a stony-iron mesosiderite that may have come from 16 Psyche. Observations indicate that Psyche has a metal-pyroxene composition, consistent with it having one of the brightest radar albedos in the asteroid belt (0.37±0.09). Its density, 4.0±0.3 g/cm³, is compatible with mesosiderite meteorites (≈ 4.25 g/cm³) and the Steinbach meteorite (≈ 4.1 g/cm³). Psyche seems to have a surface that is 90% metallic and 10% silicate rock, with 6±1% of orthopyroxene. Scientists think that these metals may be mostly iron and nickel. The NASA Infrared Telescope Facility at the Mauna Kea Observatories reported evidence (~3 μm absorption feature) of hydroxyl ions on the asteroid in October 2016 that may suggest water ice. Since Psyche is thought to have formed under dry conditions without the presence of water, the hydroxyl may have reached Psyche via past impacts from smaller carbonaceous asteroids.

Psyche 16 appears to be an exposed metallic core or a fragment of a metallic core from a larger differentiated parent body some 500 kilometres in diameter. If Psyche is indeed one, there could be other asteroids on similar orbits. However, Psyche is not part of any identified asteroid family. One hypothesis is that the collision that formed Psyche occurred very early in the Solar System’s history, and all the other remnants have since been ground into fragments by subsequent collisions or had their orbits perturbed beyond recognition. However, this scenario is considered to have a probability of just 1%.

An alternative is that Psyche was broken by impacts, but not catastrophically torn apart. In this case, it may be a candidate for the parent body of the mesosiderites, a class of stony-iron meteorites. Another possibility is that Psyche may be an endmember of diverse relic bodies left by the inner planet formation. The asteroid’s mantle may have been stripped away not by a single collision but by multiple (more than three) relatively slow sideswipe collisions with bodies of comparable or larger size. What is left is a metallic core covered by a thin layer of silicates, which reveals itself spectrally. In such a case, Psyche would be analogous to Mercury but much less massive.

Exploration of Psyche 16 asteroid

No spacecraft has visited Psyche, but in 2014 a mission to Psyche was proposed to NASA. A team led by Lindy Elkins-Tanton, the director of the School for Earth and Space Exploration at Arizona State University, presented a concept for a robotic Psyche orbiter. This team argued that 16 Psyche would be a valuable object for study because it is the only metallic core-like body discovered so far.

The spacecraft would orbit Psyche for 20 months, studying its topography, surface features, gravity, magnetism, and other characteristics and would be based on current technology, avoiding high cost and the necessity to develop new technologies. On 30 September 2015, the Psyche orbiter mission was one of five Discovery Program semifinalist proposals. The mission was approved by NASA on 4 January 2017 and was originally targeted to launch in October 2023, with an Earth gravity assist maneuver in 2024, a Mars flyby in 2025, and arriving at the asteroid in 2030. In May 2017, the launch date was moved up to target a more efficient trajectory, launching in 2022, with a Mars gravity assist in 2023 and arriving in 2026. On February 28, 2020, NASA awarded SpaceX a US$117 million contract to launch the Psyche spacecraft, and two smallsat secondary missions, on a Falcon Heavy rocket in July 2022.

16 Psyche

How 16 Psyche Got Its Name ?

The asteroid was named after the nymph Psyche, who married Cupid but was put to death by Venus. At Cupid’s request, however, Jupiter made Psyche immortal. ( in introduction)

Overview of Psyche 16 asteroid

One of the most intriguing targets in the main asteroid belt, 16 Psyche is a giant metal asteroid, about three times farther away from the sun than is the Earth. Its average diameter is about 140 miles (226 kilometers) — about one-sixteenth the diameter of Earth’s Moon or about the distance between Los Angeles and San Diego. Unlike most other asteroids that are rocky or icy bodies, scientists think the M-type (metallic) asteroid 16 Psyche is comprised mostly of metallic iron and nickel similar to Earth’s core. Scientists wonder whether Psyche could be an exposed core of an early planet, maybe as large as Mars, that lost its rocky outer layers due to a number of violent collisions billions of years ago.

Astronomers on Earth have studied 16 Psyche in visible and infrared wavelengths, as well as radar, which suggest Psyche is shaped somewhat like a potato. Observations indicate that its dimensions are 173 miles by 144 miles, by 117 miles (that’s 279, 232 and 189 kilometers, respectively). Psyche orbits the Sun between the orbits of Mars and Jupiter at a distance ranging from 235 million to 309 million miles (378 million to 497 million kilometers) from the Sun. That’s 2.5 to 3.3 Astronomical Units (AU), with 1 AU being the distance between Earth and the Sun. Psyche takes about five Earth years to complete one orbit of the Sun, but only a bit over four hours to rotate once on its axis (a Psyche “day”).

This intriguing asteroid is now the primary target of the Psyche mission. Targeted to launch in August of 2022, the Psyche spacecraft would arrive at the asteroid in early 2026, following a Mars gravity assist in 2023. Over 21 months in orbit, the spacecraft will map and study 16 Psyche’s properties using a multispectral imager, a gamma ray and neutron spectrometer, a magnetometer, and a radio instrument (for gravity measurement). The mission’s goal is, among other things, to determine whether Psyche is indeed the core of a planet-size object.

The Psyche mission will be the first mission to investigate a world of metal rather than of rock and ice. Deep within rocky, terrestrial planets—including Earth—scientists infer the presence of metallic cores, but these lie unreachable below planets’ rocky mantles and crusts. Because scientists cannot see or measure Earth’s core directly, Psyche offers a unique window into the violent history of collisions and accretion that created terrestrial planets.