Course Correction

The aftermath of the DART collision, as seen by the SOAR telescope.

On September 26, 2022, a half-ton spacecraft 6.8 million miles away and traveling four miles per second slammed into an asteroid called Dimorphos. The spacecraft was not carrying any scientific instruments, just a navigation system and camera that captured the final moments before impact into its target's oblong, rocky surface.

The crash was part of NASA's Double Asteroid Redirection Test, or DART mission, designed to test the feasibility of knocking an asteroid off course, should we detect one headed toward Earth. Dark colored, fast moving, and relatively small (compared to other objects in the night sky), asteroids are notoriously difficult to detect. The largest ones with Earth-crossing orbits are mostly known to astronomers, who closely monitor their movements. The small ones are insignificant. (About 48.5 tons of small meteorites enter the Earth’s atmosphere every day, most burning up high in the atmosphere.) It's the medium-sized ones that are the problem, the Earth-killers. Large enough to pose a threat, but small enough to slip through undetected.

Dimorphos was chosen for three reasons. First, it's in this medium range, roughly 170 meters across. Second, it's not headed toward Earth, and tinkering with its path is low-risk. Last, it's part of a binary system, revolving around its larger twin, Didymos, in an orbit that has been carefully measured. The impact was not enough to knock it out of this orbit, but it gave enough of a tap for astronomers to measure a change in velocity and trajectory.

Results show that the impact shortened Dimorphos's orbit around Didymos by 32 minutes, well beyond the success threshold of 73 seconds. The mission represents an important first step, a proof of concept for how we might protect the Earth from celestial calamity. True security, though, lies in having a suite of options available to us, and NASA also has other ideas to deflect an object. For example, we don't have to ram a spacecraft into it—violent, chaotic, and unpredictable as that is. An alternative involves sending a craft that would land on the surface, then fire its thrusters to steadily push it off course. If begun far enough away, even a small amount of force would be enough to change its orbit by tens of thousands of miles, the difference between a hit and a miss. Better yet, avoid the complication and wasted fuel of landing and just park the craft next to the asteroid. As gravity reels it toward the surface, use the thrusters to push away, then repeat, like bouncing on an invisible trampoline. The mere presence of the craft, its gravity, is enough to gently coax the behemoth off course.

**

I'm a Catholic school kid. Kindergarten through fifth grade, I wore a powder blue shirt and navy slacks, sat through Religion class & First Friday mass, and passed through musty halls under the watchful eye of dusty iconography. No-nonsense teachers kept a tight ship, with courtesy and formality strictly enforced. It was a narrow lane to occupy, with little room for asking questions. The method of instruction was rote memorization. Take math--to learn multiplication, we learned times tables in an ascending sequence, starting from the 1s and 2s, and working up to the 7s, 8s, and 9s. We went over them again and again, writing them in our notebooks and reciting them out loud as a class: "Eight-times-seven-is... fifty-six!" We were taught to do long division by hand, methodically showing our work step by step until we arrived at the answer. Homework was worksheets and quizzes, page after page of problems, over and over and over again. The other subjects were more of the same. I remember sitting on the living room couch with my mother, flipping flashcards—definitions, vocabulary, and so on. That's how I learned to learn—drill it into my brain with word tricks and anagrams, anything to remember. I got good grades. I was smart, I was told, because I could do this.

For sixth grade, I switched to a large public school. The middle school's three "houses" operated as self-contained units, each with their own teachers, administrators, classrooms, and hallways. Everything was new—culture, lockers, walking to my own classes, my own schedule. No Religion, no uniforms. In math, instead of memorization, we learned New Math, which taught logic and visualization to arrive at answers. Knowing my times tables helped, but math became something I had to "figure out". I didn't get it. Why can't I just write the answer? Once, my teacher pulled my parents aside. "I find that students who come from St. Joe's tend to be lacking in these skills."

My favorite was science. I likes airplanes, bugs, the solar system, and public school had the money and resources to explore them all. My sixth grade teacher was a quirky, enthusiastic woman. Picture Miss Frizzle with short graying hair. I still remember my astonishment the day she stood in the front corner of the room with a basketball and tennis ball, one in each hand, and asked the class, "If the Earth is this big, then how far away is the moon?" She handed the tennis ball to a student in the front row and told him to walk to a spot on the floor. "Further!", we shouted, waving him past the desk. "Stop!", said others as he was nearing the trash can, a little past halfway across the room. We quieted down to hear how we did. A wry smile came across her face. "I'm sorry, this was a trick question," she said. "To put the moon where it should be, you'd have to climb out the window and walk to the tree across the courtyard."

When college rolled around I went in undecided, leaning toward environmental science. To fulfill a requirement, I took an intro geology course taught by a younger professor, thin and balding with a goatee. We took field trips to road cuts, where the highway had been blasted through layers of shale and slate, pulling onto the shoulder to sketch folds and layers, to measure their strike and dip. We drove around and to a dozen or so spots and constructed a countywide map of bedrock geology. I took a couple more geo courses and in my sophomore year surprised myself by declaring as a major. More employable than environmental majors, my peers said. Little did I know the ground that I had charted on paper would soon dissolve beneath my feet. I was goofing off, partying, and could no longer give school my full attention. My grades started to slip. I dropped out.

The silver lining was that I had to figure out a direction, a new orientation, for myself. That was the struggle for the next two years. What do I want to do with my life? Before that point I had never really considered the question. I had thought about it only in an abstract, detached way. But now it was undeniable—the fear of not knowing, of wasted time, of being a disappointment. How did this happen? I was drifting, grasping, hurtling through space, everything so very far away.

Slowly, after working in a supermarket deli then retail for a while, I began to feel my feet under me again. I went back to school, closer to home, where I racked up a series of intensive courses in chemistry, biology, and ecology. I read long chapters in arcane textbooks, learned 500 million years of fish taxonomy, and the chain of chemical reactions that occur during plant photorespiration. Being back in class for the right reasons was invigorating. I was older and felt an ease of focus and purpose. I got A's. Soon was on the cusp of a degree in environmental science. Still, a question lingered in my mind. Am I only good at this because I can memorize it? Am I just seeking validation where I know to find it?

The final course was the "capstone", an interdisciplinary seminar that examined environmental issues from a broader, societal lens (rather than a technical one). We had been reading about the rise of "post-environmentalism", a counter-movement that was pushing back against the orthodoxies of the 1960s and 70s. Issues like nuclear weapons and climate change have forced us to reexamine our assumptions. We need new answers, to find new interpretations and new directions. For my final paper I wrote about three people doing just that: Tim DeChristopher, who served two years in prison for buying up (and not paying for) oil and gas leases at a BLM auction in southeast Utah; David Holmgren, an Aussie who argues for global economic collapse as a way to immediately halt carbon emissions and save humanity from itself; and Paul Kingsnorth, a former activist who believes that by pinning their hopes to a "sustainable" future of continued economic growth, mainstream environmentalists have sold out. He has since turned to writing and art, searching for answers of deep faith and wisdom that, in a tragic and lonely world, will truly sustain us. Writing that paper lit a fire under me. I couldn't get enough—reading, thinking, writing. his is it. Parked right there next to science the whole time.

**

I was recently introduced to the work of Rebecca Elson. At sixteen, she matriculated into Smith College, where she studied astronomy. She went on for a Master's degree at the University of British Columbia, a PhD at Cambridge, and a postdoc at the Institute for Advanced Study at Princeton. She became well-regarded for her study of globular star clusters, chemical evolution, and galaxy formation, and was among the earliest to win time using the newly-launched Hubble Space Telescope. At the age of 29, she was diagnosed with non-Hodgkin's lymphoma, and after a brief remission, succumbed to the disease in 1999, at the age of 39.

Despite her condition (and unquestionable pain) through those years, her journal, kept since she was a teenager, does not betray suffering. In 2001, a collection of her poetry titled A Responsibility to Awe was published posthumously. Reading them today, the poems have a solid, glassy quality of someone who is sure. For Elson, writing was a lifeline, a necessary deflection. A kind of jiu-jitsu for life. I wish I had started earlier.

We Astronomers

We astronomers are nomads,

Merchants, circus people,

All the earth our tent.

We are industrious.

We breed enthusiasms,

Honour our responsibility to awe.

But the universe has moved a long way off.

Sometimes, I confess,

Starlight seems too sharp,

And like the moon

I bend my face to the ground,

To the small patch where each foot falls,

Before it falls,

And I forget to ask questions,

And only count things.

- Rebecca Elson