Wednesday, 31 March 2021

NASA Begins Assembling Spacecraft to Study Enormous Metallic Asteroid

NASA’s Jet Propulsion Laboratory (JPL) in California got a package last week, and it’s much more important than the smattering of Amazon impulse purchases that show up on most of our doorsteps. JPL has taken delivery of the Psyche spacecraft from Maxar Technologies and is now starting final assembly. Next year, this piece of hardware will ride a SpaceX rocket into orbit, and then it’s off to the asteroid belt to study its namesake, the metal-rich asteroid 16 Psyche. 

JPL is shooting for an August 2022 launch for Psyche, which will start it on a nearly four-year journey to the asteroid belt between Mars and Jupiter. Along the way, it will pass within just 500 kilometers of Mars. Then, it’s on to 16 Psyche, the heaviest known M-type asteroid that all by itself has about 1 percent of the asteroid belt’s mass thanks to its mostly iron-nickel composition. Scientists believe that Psyche is the exposed core of a protoplanet that collided with another object in the distant past, stripping away its outer crust.

The chance to study a planetary core up close, even one that’s been exposed to space for billions of years, is something NASA couldn’t pass up. The agency chose Psyche as part of the Discovery program in 2017. Missions under the Discovery banner are cheaper than those in New Frontiers or Flagship programs, which can run into the billions of dollars. Psyche is expected to cost around $117 million, including launch aboard a SpaceX Falcon Heavy rocket. 

Psyche is an average of 111 km (69 miles) in diameter with a maximum diameter of 277 km, making it larger than the states of Rhode Island and Delaware.

The newly arrived construct at JPL is what’s known as the Solar Electric Propulsion (SEP) Chassis. This large, boxy module accounts for more than 80 percent of the total spacecraft mass and includes fully integrated propulsion, navigation, thermal, and electrical systems. Now it’s up to JPL engineers to complete the spacecraft by integrating communication, scientific instruments, and other systems. Psyche will reach its destination with the help of an SPT-140 engine, a Hall-effect thruster that uses solar power to accelerate xenon ions to produce thrust. It’s not much thrust — the SPT-140’s thrust is measured in micro-newtons — but it can accelerate continuously for long periods. 

Psyche will use three instruments to study the asteroid: a multispectral imager to take photos of the surface, a gamma-ray spectrometer to analyze the asteroid’s elemental composition, and a magnetometer to measure its magnetic field. The image above is just an artist’s rendering, so we don’t know what the spacecraft will discover when reaching its eponymous asteroid. Regardless, this mission could change our understanding of planetary formation.

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