NASA tries to launch mission to mysterious metallic asteroid – 10/11/2023 – Science

NASA intends to begin this Thursday (12), more than a year late, the Psyche mission, the first of the American space agency to be aimed at a metallic asteroid — something that scientists imagine as the closest it can get to undertake a journey to the center of the Earth itself.

The spacecraft will be launched from the Kennedy Space Center, in Florida (USA), by a Falcon Heavy rocket, with takeoff scheduled for 11:16 am (Brasília time), in an instantaneous launch window — which means that, if anything prevents departure at the scheduled time, a new attempt can only be made the following day. Opportunities extend until the 25th.

Selected in 2017 by the Discovery program, promoted by NASA to select low-cost missions commanded by a scientist, Psyche was originally going to fly last year, but problems with testing the flight control system prevented it from meeting the schedule.

It was with some bitterness that the space agency promoted the postponement. Although it would only result in a one-year delay in the launch itself, the move would add three years to the journey to the final destination. If it left in 2022, the spacecraft would reach the asteroid Psyche, located in the belt between Mars and Jupiter, in 2026. Now, it will only be able to reach the target in 2029.

These are the hardships of celestial mechanics. The trajectory chosen for the probe involves a flyby of Mars, in order to use the planet’s gravity as a slingshot to propel it into Psyche’s orbit. However, the relative positions of Earth and Mars change a lot from one year to the next, and with the new launch date the meeting will only take place in May 2026. Therefore, if all goes well, the mission should arrive at Psique in August 2029.

A peculiar object

The asteroid Psyche was the 16th discovered in the asteroid belt, in 1852, by the Italian astronomer Annibale de Gasparis. With an irregular shape and 280 km in diameter on its longest axis, it is one of the largest objects of its kind in the Solar System. And it has a peculiarity: it is much denser than the average asteroid and has between 30% and 60% of its composition in metals.

According to some estimates, if it could be exploited, it would be worth 10 quintillion dollars in iron, nickel and other precious materials. Of course, this number doesn’t make much sense, firstly because bringing this immense amount of metals to Earth would bring down their market price, and secondly because there is no technology available to mine even nearby asteroids, let alone those in the belt between Mars and Jupiter.

“No, NASA is not mining asteroids,” explains Lindy Elkins-Tanton, mission leader and researcher at Arizona State University (ASU) in Tempe. “What NASA is doing is fundamental science, research missions that go to asteroids and try to learn more about them. And they will help any future efforts to mine asteroids.”

For now, the main focus is exploring these objects to understand how the planets formed. In this context, Psyche appears with special prominence.

We know that asteroids are generally remnants of the planetary formation process — in essence, the bricks left over from the birth of Earth and the other planets in the solar family, formed in a disk of gas and dust that generated progenitor objects known as planetesimals.

Psyche’s unusual composition, however, suggests something else: it may well be the exposed core of a planetesimal, with its large concentration of metals. The idea is that it was hit by many impacts — which must have been common at the time of the formation of the Solar System, 4.6 billion years ago — that ejected much of its outer, rocky layer, leaving only the dense core. back.

Hence the notion that visiting Psyche may be the closest one can get to traveling to the center of the Earth — an unfeasible journey due to the enormous pressure and temperature present in the deep interior of the planet.

Located about three astronomical units (450 million km) from the Sun, which is equivalent to triple the distance that Earth is from its parent star, Psyche is not an ideal target for telescopic observations, and little is known about it. The exact shape, for example, can only be determined when the probe gets there.

And something the mission team is ready to deal with is surprises. If the hypothesis that the asteroid is a planetesimal nucleus is not confirmed, it could turn out to be an object of a type never seen before, which will require a review of the understanding of how the Solar System was formed.

Four instruments and one experiment

To carry out its mission, the spacecraft has two twin sets of five solar panels, capable of powering the onboard systems and the four onboard Hall effect thrusters. They are a type of ionic propellant, which works by using electricity to ionize (remove electrons) from xenon atoms. Then, with magnetic fields, these particles are ejected at high speed and, in doing so, propel the spacecraft forward.

It is not a very powerful process (the thrust force is equivalent to the weight of a small battery on Earth), but it is extremely economical: gaining this small acceleration over a long period, the spacecraft ends up acquiring a lot of speed — more than it would otherwise capable with conventional chemical propulsion.

It will be the first time that thrusters of this type have been tested beyond the Moon’s orbit. The solar panels will produce 21 kilowatts when they leave Earth, but only between 2.3 and 3.4 kilowatts when they are in orbit around Psyche, much further away from the Earth. Sun.

With this power, the probe will power the three instruments that will study the asteroid: a multispectral imager, capable of recording the topography in visible light and near infrared, in addition to identifying mineralogical composition; a gamma ray and neutron spectrometer, to capture the chemical composition of the surface; and a magnetometer, which will look for evidence of an ancient magnetic field — if found, it will be strong evidence that Psyche formed the core of a planetary body in the past.

A fourth instrument, so to speak, is the probe’s communications system. Although the function of the antennas is to allow the exchange of information between the spacecraft and JPL (NASA’s Jet Propulsion Laboratory), which manages the mission, the analysis of radio waves makes it possible to investigate variations in the asteroid’s gravitational field as the probe rotates. around it, giving clues as to how its interior is organized.

Finally, Psyche takes a hitchhiking experiment, DSOC, or Deep Space Optical Communications. It is NASA’s first attempt to develop a system that allows broadband transmissions using lasers instead of radios. It is estimated that data transmission rates could increase by ten to a hundred times, something that would be very important for future manned missions to Mars.

The entire package — Psyche, DSOC and the launch cost — cost NASA US$1.2 billion (R$6.1 billion). It is expected that the spacecraft, after reaching its destination in 2029, will operate for at least 26 months, making several orbits around the mysterious asteroid.