From A Portrait of the Scientist as a Young Woman by Lindy Elkins-Tanton. Copyright © 2022 by Linda Elkins-Tanton. Reprinted by permission of William Morrow, an imprint of HarperCollins Publishers.
“What happens if it blows up?” a high school student recently asked me. “Do you get a do-over?”
Ah, no. There are no $800 million space mission do-overs in my world. At the moment of an explosion, we are finished.
Soon, if luck, sweat, and the fates align, our rocket will launch our spacecraft off the Earth and begin its 3.4-year journey to the asteroid (16) Psyche. Each asteroid is assigned a number at the time of its discovery, and Psyche was the 16th that we human beings have discovered, of the perhaps 1.5 million asteroids in the asteroid belt. There are not many kinds of solar system objects left to be explored, and Psyche is one of them. We think that it is made mainly of metal. We think—though we don’t know for sure—that Psyche may be a piece of one of the first metal cores to form in our solar system. This is why we are going. The molten metal in a very early, hot little planet, called a planetesimal, would have sunk to the interior and formed its core. Then, this planetesimal was broken into pieces rather than incorporated into the Earth or the other big planets of today. Psyche may be part of that exposed core.
Humans have gone to the moon, and we’ve sent robotic spacecraft to investigate other rocky planets (Mercury, Venus, Mars), gas and ice giant planets (Jupiter, Saturn, Uranus, Neptune), and icy asteroids and moons (Ceres, Enceladus, Europa, and a couple of comets), but there is one category of solar system object that we have never investigated: the small category of asteroids that we think may be made primarily of metal.
Earth’s core and the cores of the other rocky planets are metal. Earth’s core is also the source of our magnetic field, the field that may help protect our atmosphere and keep our planet habitable. Metal is clearly a fundamental building block of our habitable planet. But we will never see our own core. To see a metallic world, we think we need to go to Psyche. We won’t know with certainty until we get there whether Psyche is a part of a planetesimal core, but Psyche is the only large asteroid in our solar system that is likely to be metallic.
Our solar system started as a vast sparse cloud of dust and gas that was hit with a shockwave, probably the shockwave of a nearby star exploding into a supernova. That supernova was the trigger for our birth. The shockwave compressed the cloud and part of the cloud began to collapse under its own gravity, spinning, forming disks with concentrations of dust and gas in their centers, growing to become young stars. In the spinning disk of plasma, dust, and gas around the nascent star, the first solids formed, little pebbles of minerals rich in calcium, aluminum, and titanium, the elements that condense to solids at the highest temperatures as the hot disk is cooling down from being plasma or molten. These so-called calcium-aluminum inclusions are found inside meteorites that fall to Earth today, tiny survivors of the rapid, violent process of material being crushed into bigger and bigger clumps by pressure and shockwaves in the spinning disk, and the clumps, some as big as continents, colliding and sticking together to form planets.
Those little calcium-aluminum inclusion pebbles formed 4.568 billion years ago, and they mark what some call the beginning of our solar system, long before the Earth had formed. If we imagine our 4.568-billion-year-old solar system as a 24-hour day, within the first 20 seconds of that 24-hour solar system—about 1 million years after those first pebbles formed—rock and metal had already collected together into planetesimals, just tens to hundreds of kilometers in diameter. These are the continent-size clumps.
One of these planetesimals, we think, was the parent body of the asteroid Psyche. We believe that Psyche, now an asteroid orbiting be-tween Mars and Jupiter, is the remnant of a battered planetesimal. But just as the length of time between ourselves and the original planetesimals makes seeing that early population of clumps impossible, the distance between Earth and Psyche makes little Psyche, just 138 miles in diameter (the width of Massachusetts without Cape Cod, or the north–south height of Switzerland), too small to see clearly from Earth. The difference is that while we can’t go back in time, we can bridge that gulf of space. We can send a robot to find out what Psyche really is.
On that day this summer, the efforts of 800 people, 11 years, 2,000 pages of proposals, perfect wires and perfect software and perfect solar panels and bolts and joints and struts will be perched on the top of about 20,000 kilograms of explosive propellant, and our spacecraft will be sent off into the void. We think it will all work. We are doing everything in our power to make sure it will. We hope it will work.
But it might fail. Space is hard.
There aren’t many people who have led deep space missions and each of us followed our own path. Indeed, there may be no one single way a person gets to lead a space mission. But if there are a series of paths that have worked in the past, I can say with some certainty that I did not follow any of them.
And now I reread these words as I sit in my office at Arizona State University in June, on a day filled with urgent meetings about the mission. (Disclosure: ASU is a partner with Slate and New America in Future Tense.) We recently made the decision to slide our launch readiness day (LRD, of course, in space-speak) seven weeks later, to Sept. 20. This kind of launch date change usually happens because of an unexpected problem, and that’s where we are now. Not a good feeling.
For years we’ve been writing new flight software to control the spacecraft and all it does. To check and test that software, we use a testbed, which is a hardware and software model of the spacecraft. We can’t use the spacecraft itself for test, can’t order the spacecraft to roll, or communicate, or thrust, while it’s on Earth, hence the testbed. But we just discovered that the testbed is not working correctly.
This is the conundrum of engineering problems: You can’t predict when they will be solved until you have identified the root cause of the problem and fixed that root cause. So now we live every day in an intense storm of work to fix the testbed, with daily update meetings. Keep your fingers crossed! Space is hard … and building spacecraft during the COVID pandemic, especially hard. And so we persist, persist, persist and we look forward to the launch that right now seems like a finish line, but of course, is once again just the start of a new adventure.
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