Fractal steps

I've been reading a lot about astronomy and the solar system recently for a writing project I've been working on, and one of the books that I recently picked up was The Asteroid Hunter: A Scientist's Journey to the Dawn of our Solar System, by Dante S. Lauretta, the Principle Investigator of the OSIRIS-REx mission that recently visited an asteroid and returned to Earth with some samples of its surface.

It's an engaging and breezy read, one that sheds not only light on the nature of asteroids in our solar system and this mission, but also the complicated process that it takes to put such a massive undertaking together.

Lauretta moves through his career as an scientist, detailing how his early love of science fiction and the promise of the search for alien life through programs like SETI helped lead him to begin studying chemistry and eventually, to the composition of asteroids and the possibilities that they hold some of the critical organic building blocks that possibly led to the emergence of life on Earth.

It's a complicated subject, and he uses this book to neatly break down the chain that takes you from organic chemistry to the rocks – or really, piles of loosely-consolidated rubble – that are floating out there in our solar system, and how he went from studying and collecting meteorites in Antarctica to leading a $1.6 billion mission to the asteroid Bennu, for a novel sample recovery mission.

That mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer), launched in September 2016, and made its way out to an asteroid called 101955 Bennu. It arrived in December 2018, and began mapping the surface of the body to find a suitable sampling site. After two years of exploration, the spacecraft dipped down to impact the asteroid's surface in October 2020, and bounced off with some precious fragments of asteroid regolith – twice the amount they'd hoped to get, before returning to Earth and dropping off its sample canister to Earth in September 2023.

The spacecraft has since been retasked and is now headed for an extended mission to 99942 Apophis, the asteroid that made headlines twenty years ago when it was discovered and believed to be a potential threat to the planet. It'll arrive in 2029.

Lauretta uses this book to showcase the advances we've made in the study of our solar system, now even more useful after the recent headlines about 2024 YR4, an asteroid that was believed to be on course for Earth in 2032. (The chances of it hitting Earth have dwindled down to almost nothing.) Space and astronomy are complicated topics, and our awareness of the fields are often shaped by dramatic headlines around successes, failures or random discoveries, PR and publicity stunts, or by the pictures that get sent back to Earth by our robotic emissaries.

What's often left out of those stories is the work that goes into those programs, and this is where Lauretta really shines a light into just how immense these programs are. He goes back to the initial meetings that led to the OSIRIS-REx project: aerospace contractor Lockheed Martin had a spacecraft design that they wanted to pitch to NASA, and Lauretta was brought on by his mentor and project Principle Investigator Michael Drake because it aligned with his research goals.

What struck me about this book is how it's a story of a project that where you scratch the surface, there's more complexity and challenges lurking underneath. It took Lauretta and Drake and their team three tries before they had refined the outlines of their proposal to the point where it was approved by NASA. Each time, NASA pushed back on various things that they took issue with: their initial target asteroids, the design and equipment on the spacecraft, and so forth, prompting them to go back to the drawing board and make adjustments.

But even after the project was approved and the spacecraft was designed, they faced other issues: design and engineering problems that emerged as they built the spacecraft, all with the memories of spacecraft and probes that had failed because of human errors, like that time the Mars Climate Orbiter burned up in Mars's atmosphere because one team used metric measurements while another used imperial ones.

Once the probe arrived at Bennu, Lauretta plays out a fascinating story of scientific discovery and adaptation. The asteroid is hard to see: he described it as being about the same color as fresh pavement, and the team really didn't know what to expect when they arrived on the asteroid. Their initial thought had been that it would be almost sandy – Lauretta had described it as a trip to the beach.

But as OSIRIS-REx approached and began taking images, they discovered that the surface was incredibly rocky, littered with hundreds of massive boulders: the smooth landing surface that they'd hoped for just didn't exist. They planned for that contingency, and had Lockheed Martin's engineers devise strategies to map out the surface and better understand what Bennu is like. Lauretta laid out some interesting tactics for eventually tackling this problem: pulling together his entire team to eyeball the images that came in, looking for potential landing sites, and then whittling down the list until they had four. As those sites had their plusses and minuses, they worked to figure out additional strategies for potential errors that came up, like the spacecraft deciding to abort a landing if it detected a problem, and how they'd mitigate it.

The contact on October 20th, 2020 brought its own surprises: where they expected to hit the surface, snag some samples and bounce right off, the probe ended up sinking about the length of one's arm into the surface before blasting back off again. The probe collected more than twice the amount that they'd hoped for, and when it took off, it left behind a considerable crater and cloud of debris.

What they ended up recovering from the asteroid was a lot of carbonate minerals, lots of water (about 700,000 metric tons of it), and that the surface is constantly emitting plumes and clouds of debris. It's essentially a big pile of mud that an astronaut would sink into if she stepped onto the surface.

What I appreciated the most about this book is how it illuminates how the processes that Lauretta's describing are sort of like a fractal pattern: you can endlessly zoom in and get ever-greater detail as you do so. Each step along the way of this particular journey, Lauretta and the rest of his team started the program with some basic assumptions about Bennu and the spacecraft, and as they came closer and closer to the asteroid, they adjusted their plans and adapted.

This is what I get the most excited for about science: that simple process of discovery and seeing how it does – or doesn't – line up with the predictions that you've formulated. Reality is what it is: every new datapoint or discovery adds to our picture of the world. When you figure in the costs of a space probe that costs hundreds of millions of dollars, you have to balance the need to preserve that investment by eliminating as much risk as possible, while also remaining flexible to tackle those unexpected things that crop up.

This is something that I've been thinking a lot about lately: the point where the rubber meets the road, and where abstract theory meets cold, hard reality: we can imagine and predict how the world operates based on what information we have and extrapolate accordingly, but it's how we react when we encounter those things that change how we see the world around us.

This book provides a good window into not just the science and things that we learned, but how an operation with a ton of moving parts can not only function, but thrive as it sets out to explore beyond our world. As such, it's a fascinating, optimistic, and accessible read, one that has my head spinning with a better understanding of how much we've learned – and how much we have yet to learn about solar system.