Is the asteroid Psyche really a hunk of mostly metal? Is the object, which is nearly as wide as Massachusetts, the core of a baby planet whose rocky outer layers were knocked off during a cataclysmic collision in the early days of the solar system?

Right now, all that astronomers can say is maybe, maybe not.

NASA launched a spacecraft, also named Psyche, on a journey to the asteroid belt between Mars and Jupiter to find out.

When is the launch, and how can I watch it?

After an earlier delay this week because of poor weather, the mission lifted off on time on for Friday at 10:19 a.m. Eastern time from Kennedy Space Center. The spacecraft is flying on Falcon Heavy, the largest of SpaceX’s orbital rockets, which is needed to provide the power to loft the massive Psyche spacecraft. The flight is being streamed live on NASA TV and on the agency’s YouTube channel, starting at 9:30 a.m. Or you can watch it in the video player embedded above.

There was an instantaneous launch opportunity each day — meaning that the rocket had to lift off at one particular moment. Several minutes into the flight, the spacecraft reached space and continued its journey to put the spacecraft into its planned orbit.

What is Psyche?

The asteroid named Psyche was spotted in 1852 by Annibale de Gasparis, an Italian astronomer, and named for the Greek goddess of the soul. It was just the 16th asteroid to be discovered.

Observations starting in the 1960s with telescopes, and later radar, suggested that Psyche differed from other asteroids in the region between Jupiter and Mars.

Scientists also found that it was potentially much denser than rock.

“Some of those early estimates were like, wow, this is really quite unusual,” said Jim Bell, a professor of earth and space exploration at Arizona State University who will lead studies of the asteroid with a camera aboard the spacecraft.

Psyche appeared to be almost pure metal, giving rise to the thought that it could be the remnant of a core of a baby planet. Or that hypothesis could be completely wrong.

“Psyche could be something entirely different than that,” said Lindy Elkins-Tanton, a professor of earth and space exploration at Arizona State University who serves as the mission’s principal investigator. “I would love to be totally surprised.”

More recent measurements have led to lower estimates of the asteroid’s density, suggesting it is made of metal plus something else — perhaps rock, perhaps empty space.

“My best guess is that it’s more than half metal, based on the data that we’ve got,” Dr. Elkins-Tanton said.

What happens after the launch?

The Psyche spacecraft will swing by Mars in May 2026, using its gravity as a slingshot toward Psyche the asteroid, arriving 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 with a variety of instruments.