Psyche on Its Way to Metal-Rich Asteroid

Psyche on Its Way to Metal-Rich Asteroid

NASA’s Psyche spacecraft started a billion mile journey to an asteroid by that name between Mars and Jupiter this morning. Of all the thousands and thousands of asteroids, Psyche is one of only nine discovered so far that is composed primarily of metal instead of rock. Scientists think it may have been the core of a tiny planet and thus may hold clues to the cores of Earth and other planets. Psyche also is being used as a technology testbed for a Deep Space Optical Communications system.

Psyche lifted off at 10:19:43 am EDT from Kennedy Space Center on a SpaceX Falcon Heavy. This is NASA’s first use of a Falcon Heavy, which has a central core booster and two side boosters. SpaceX reuses its first stages and the two side boosters had already been used on three previous launches. They landed back at Cape Canaveral Space Force Station and will be used again for a DOD mission and then for NASA’s Europa Clipper mission next year about this time. The central core stage was not recovered.

Discovered in 1852, Psyche was the 16th asteroid ever identified and its official name is 16 Psyche, named after the Greek goddess of the soul. Psyche’s distance from Earth varies between 186-372 million miles (300-600 million kilometers), but because of the circuitous route the spacecraft is taking, including a gravity assist from Mars, it will travel 1.37 billion miles (2.2 billion km).

NASA’s Psyche spacecraft takes a spiral path to asteroid Psyche, as depicted in this graphic that shows the path from above the plane of the planets, labeled with key milestones of the prime mission. NASA/JPL-Caltech

Scientists concede they really don’t know very much about Psyche — that’s why they’re sending a spacecraft to study it — but Earth-based measurements indicate it is mostly made of metal, like the centers of Earth and other rocky planets. They can’t drill down to the center of Earth, so this is an alternative to help understand how planets like ours formed. Principal Investigator Lindy Elkins-Tanton from Arizona State University quips “we’re going to outer space to explore inner space.”

NASA created an illustration of what Psyche might look like, but Elkins-Tanton emphasizes they really don’t know much more than its size — comparable to Massachusetts without Cape Cod — and density.  Psyche is very dense (212-256 pounds per cubic foot or 3,400-4,100 kilograms per cubic meter), 173 miles (280 km) across at its widest point, 144 miles (232 km) long, with a surface area of 64,000 square miles (165,800 square km).

Illustration of what the Psyche asteroid might look like. Credit: NASA/JPL-Caltech/ASU (Peter Rubin)

Elkins-Tanton jokes that she describes Psyche as shaped like a potato because “potatoes come in many shapes, so I’m not wrong.” During a science briefing earlier this week, she explained what she and her colleagues theorize about Psyche, but ended by saying they are “almost certainly completely wrong. … We’re going to be surprised.”

After the spacecraft arrives in July 2029, it will orbit the asteroid for about two years using a magnetometer to measure the magnetic field, a multispectral imager to capture images and other data about the surface, and spectrometers to analyze neutrons and gamma rays coming from the surface to determine what elements are present.

The spacecraft is hosting the Deep Space Optical Communications (DSOC) technology demonstration to use optical (laser) instead of radio frequencies to communicate with Earth. DSOC will not be used for transmitting Psyche data, but only for testing laser communications at that distance, which has never been done but could enable a 10-fold increase in data rates. A laser beam will be transmitted to Psyche from NASA’s Table Mountain Facility in California to serve as a beacon for DSOC, which will send laser signals back to Caltech’s Palomar Observatory.

The mission has had a long journey already. Managed by the Jet Propulsion Laboratory (JPL), the $1.2 billion spacecraft was supposed to launch a year ago, but in June 2022, Elkins-Tanton and her team concluded they didn’t have enough time to test the software and needed to postpone the launch. Psyche and Earth are only aligned properly once a year, so that meant waiting until now. To cover the increased cost, NASA delayed a completely unrelated mission to study Venus, VERITAS, for at least three years. An Independent Review Board set up to ascertain what went wrong found many underlying causes at JPL, some pandemic-related, and later gave JPL kudos for responding to its recommendations, but VERITAS is paying the price. The Planetary Society is leading a petition to Congress to shorten its delay.

Psyche’s launch comes just three days after NASA revealed the first samples returned from a completely different type of asteroid, Bennu, by the OSIRIS-REx spacecraft. Psyche will not be bringing samples back. The Psyche asteroid is much further away than Bennu and not enough is known about it to even attempt grabbing something off the surface.

Studying asteroids is important not only to learn how the solar system formed 4.5 billion years ago, but to defend Earth from any that pose threats.

Asteroids are rocks in space. When they plummet through Earth’s atmosphere they are called meteors and anything that survives to the ground is a meteorite. The impact of a very large asteroid 65 million years ago is thought to have led to the extinction of the dinosaurs. Small asteroids routinely enter the atmosphere and burn up, creating delightful meteor showers. In between are asteroids of the size that can cause local or regional damage like the meteor that exploded in mid-air over Chelyabinsk, Russia in 2013, injuring more than 1,000 people from broken glass that shattered from the sonic boom.

Congress directed NASA to locate and track Earth-threatening asteroids 140 meters (450 feet) or more in diameter and NASA created a Planetary Defense Coordination Office to not only find them, but develop methods to divert them. PDCO had its first flight mission last year, the Double Asteroid Redirection Test (DART), which intentionally impacted a small asteroid, Dimorphos, that orbits a larger one, Didymos, and altered Dimorphos’s orbit, the first time humans have changed the trajectory of another object in the solar system.

DART’s last full image of Dimorphos before deliberately crashing into it, September 26, 2022.

In April 2029, three months before Psyche reaches its destination, the world’s attention may be focused on a different asteroid, Apophis, that will make a close approach to Earth. Scientists are confident it will not impact our planet, but it will come within about 20,000 miles (32,000 kilometers) and be visible to the naked eye.

After dropping off its Sample Return Capsule two weeks ago, the main OSIRIS-REx spacecraft headed off a new assignment — to meet up with Apophis after it passes Earth to study it in detail. The mission has been renamed OSIRIS-Apophis Explorer or OSIRIS-APEX. NASA and the international planetary defense community also are looking into the possibility of launching a spacecraft to fly past Apophis before it reaches Earth so they can compare before and after data, but no plans have been set.

All in all, NASA Planetary Science Division Director Lori Glaze counts seven NASA asteroid missions currently operating or in development:

  • Psyche
  • OSIRIS-REx (now in the curation and data analysis phase)
  • Lucy, on its way to the Trojan asteroids
  • New Horizons, which flew past Pluto and is now in the Kuiper Belt at the outer edge of the solar system looking for small rocks called Kuiper Belt Objects (it flew past one in 2019)
  • NEO Surveyor, a new space telescope scheduled for launch by 2028 designed specifically to find asteroids
  • NEOWISE, an existing spacecraft (originally the Wide Field Infrared Survey Explorer or WISE) that was repurposed for locating asteroids

Right now NASA is celebrating what it calls Asteroid Autum: the return of the OSIRIS-REx samples on September 24, the one year anniversary of DART’s impact of Dimorphos on September 26, Psyche’s launch today, and Lucy’s arrival in the main asteroid belt where it will make a close pass of asteroid Dinkinesh (1999 VD57) as an engineering test of its navigation system on November 1.

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