Is asteroid Psyche really a chunk of mostly metal? Is an object nearly as wide as Massachusetts the core of a baby planet whose rocky outer layers were torn off during a cataclysmic collision in the early days of the Solar System?
Right now, astronomers can only say maybe, maybe not.
NASA launched the spacecraft, also named Psyche, on a trip to the asteroid belt between Mars and Jupiter on Friday morning to find out.
“We’re actually going to see some kind of new object, which means a lot of our ideas will be proven wrong,” said Lindy Elkins-Tanton, a professor of Earth and space exploration at Arizona State University who serves as the mission’s principal investigator.
When she was proven wrong, she added, “I think it’s the most exciting thing in science.”
This journey to find answers began on Friday at 10:19 AM ET. The Falcon Heavy, the largest of SpaceX’s operational rockets, lifted off from the Kennedy Space Center in Florida, sending the massive spacecraft on a journey that will last about six years and cover billions of kilometers.
Friday’s flight defied early adverse weather forecasts for what appeared to be a flawless start. After about eight minutes of flight, the rocket’s upper stage entered a 45-minute inertia period, during which it will prepare to deploy the spacecraft on its flight away from Earth. You can watch the flight in progress in the video player above or at NASA’s YouTube channel.
An asteroid named Psyche has long been a strange mystery. Spotted in 1852 by Italian astronomer Annibale de Gasparis, it is named after the Greek goddess of the soul and was only the 16th asteroid discovered. In the first observations, it was, like other asteroids, a star-like point of light moving in an orbit around the Sun, and nothing more.
Beginning in the 1960s, astronomers observed through telescopes that Psyche’s color was similar to iron meteorites that hit Earth, said Jim Bell, a professor of Earth and space exploration also at Arizona State University who will lead studies of the asteroid with the spacecraft’s camera instrument. Astronomers bounced radar pulses from Psyche, and the reflections coming back to Earth were brighter than those coming from other small objects in the asteroid belt.
“It became quite clear that there was some component of the surface that was highly reflective of radars,” said Dr. Bell. “And the easiest way to do that is with metal shards.
And then when scientists observed Psyche passing relatively close to larger worlds, its orbit was skewed in a way that suggested something quite massive and potentially much denser than rock.
Most rocks, such as granite, have a density of two to three grams per cubic centimeter. Water, whether liquid or ice, is about one gram per cubic centimeter. Metals like iron are much denser, between six and nine grams per cubic centimeter.
“Some of those early estimates were like, wow, this is really quite unusual,” said Dr. Bell.
Psyche looked almost pure metal. Earth’s core is made of iron and nickel, and Psyche’s measurements led to the idea that it might be a remnant of a similar core that belonged to the baby planet. Such worlds are known as planetesimals, where the temperatures are high enough for the denser metals to melt and fall to the center.
It’s impossible to probe the core of a planet like Earth 1,800 miles below the surface, but a visit to Psyche could provide more information about what’s at the center of our planet.
Or this hypothesis may be completely wrong.
“Psyche could be something completely different than this,” said Dr. Elkins-Tanton. “I’d like to be completely surprised.
More recent measurements have led to lower estimates of the asteroid’s density, a little less than four grams per cubic centimeter: still denser than rock and ice, but not as dense as metal. This suggests that Psyche is made of metal and something else: maybe rock, maybe empty space.
“My best estimate is that it’s more than half the metal based on the data we have,” said Dr. Elkins-Tanton.
If Psyche turns out to be full of precious metals, it is too far away to be mined using current technology. Dr. Elkins-Tanton notes that even at its closest, Psyche is about 150 million miles from Earth, which is about five times more than Earth is from Mars on both planets. nearest possible approach.
The Psyche mission was supposed to be launched a year ago. The spacecraft has already been sent to the Kennedy Space Center. But engineers ran out of time to test all the navigation software before the launch window closed.
After launch, the Psyche probe will head towards Mars, swing by the red planet in May 2026 and use its gravity as a slingshot towards the asteroid Psyche, which will arrive in August 2029 after traveling 2.2 billion miles.
The spacecraft will spend at least 26 months in orbit around the asteroid studying the body using instruments that include a magnetometer to measure magnetic fields, a camera to take pictures of the surface and a gamma spectrometer to identify what the asteroid is made of. .
In addition, the radio station will be used to measure the asteroid’s gravity by measuring slight shifts in the Doppler shift frequency of the signal, which rises as it moves toward Earth and falls as it moves away. This could provide further insight into its composition and internal arrangement.