NASA will launch the Psyche probe towards the eponymous asteroid by the end of this month. The mission will send the spacecraft on a journey of 3.5 billion km towards the 16Psyche asteroid. This asteroid is not just an ordinary space rock. It could be the metallic core of a planet whose outer layers were stripped away long, long ago.
If the agency is correct about this hypothesis, 16Psyche has the potential to offer us a unique way to study the Earth‘s core. Both may have similar metallic compositions, but even if the hypotheses were incorrect, there would still be cause for celebration. As Lindy Elkins-Tanton, the principal investigator of Psyche, says, the alternative to Psyche could be just as intriguing as the first hypothesis.
Two Hypotheses
16Psyche is made of material that formed near the Sun, but then was reduced in such a way that oxygen atoms detached from iron atoms. In turn, the latter would have become the metallic form of the asteroid. “This is a type of material that has been hypothesized by planetary scientists for a long time. Actually, we’ve never found any before” Elkins-Tanton said. “Think what it means to have just one object like Psyche in the entire Solar System“.
“The other idea is that Psyche is a kind of unfused primordial body. Formed from the very earliest materials of the solar system that came together under gravity” said Ben Weiss, deputy principal investigator of the Psyche mission. This case, we would see an extraordinary fossil of the primordial Solar System.
In both hypotheses, this ambitious enterprise is set to achieve milestones that will be marked on the pages of our astronomy books. Infact, Psyche has already achieved several milestones.
Sci-Fi Propulsion
David Oh, chief engineer of operations at NASA’s Jet Propulsion Laboratory (JPL), states that this will be the first mission to use Hall effect thrusters in interplanetary space. Essentially, these thrusters use electricity to ionize xenon gas. Ionization is the process that removes or adds one or two electrons from the atoms that make up a substance, in this case a gas.
After ionization, the atoms acquire a charge, becoming ions. The charged ions form an electric field that can, through a series of steps, create thrust. “They come out of the thruster at 15 kilometers per second” Oh said. ‘It’s five times faster than the speed of fuel coming out of a regular chemical rocket. Thirty years ago, when I was a student, I worked on Hall effect thrusters. At the time, it was considered an esoteric and futuristic technology. It seemed like the kind of thing you heard about in Star Wars and Star Trek“.
Using this technology, the Psyche spacecraft is expected to reach its metallic target in 2029. It seems like a long time, but the path between NASA ‘s Psyche probe and the asteroid is very complex. “The launch is just the beginning” Oh said.
Psyche’s Path to the Asteroid
After lifting off from our planet with a SpaceX Falcon Heavy, Psyche will begin to move towards its target located between Mars and Jupiter. Then the ion thrusters come into play. “These thrusters can work for long periods of time” Oh said. “The thrust accelerates it to the high speeds we need to navigate towards Mars”.
Once the spacecraft has reached the vicinity of Mars, it will dive into the gravitational influence of the Red Planet to be flung like a slingshot towards the 16Psyche asteroid. “Then we’ll restart our ion propulsion system and use it to complete the rest of our journey towards Psyche”.
Once it reaches its destination, the probe will reach the highest of the four planned orbits around the asteroid. At this stage, a lot of data will be collected about the space rock. Finally, slowly, the NASA Psyche probe will descend into orbits closer to the eponymous asteroid. At that point, a series of measuring instruments will come into play. A gamma-ray neutron spectrometer capable of investigating the type of elements that make up the asteroid and two magnetometers to understand the object’s magnetic field.
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