San Antonio Express-News

Other close encounters to watch for

- By Chris Combs Chris Combs is the Dee Howard endowed assistant professor and aerospace program coordinato­r in the UTSA Department of Mechanical Engineerin­g.

The sky isn’t falling … yet.

We all have plenty to worry about — from COVID-19 to climate change to holiday shopping, and even the fates and fortunes of our chosen football team (Birds Up!) — so you don’t need me adding something to your list.

Still, here’s some bad news: You should be worried about space, too. It’s easy to forget space is a mere 60 miles over our heads, with the Internatio­nal Space Station flying by at 17,500 miles per hour about 250 miles up. We take for granted how much we’ve come to depend on the global space infrastruc­ture of satellites that provide GPS, weather forecasts and instant global communicat­ion.

It’s time to start paying attention to what’s happening in space.

China recently tested a “fractional orbital bombardmen­t system,” which is a fancy way of saying it flew a nuclear-capable hypersonic missile around the globe before hitting a target in China. The Chinese could use a system like this to strike targets in the U.S. with virtually no warning, and at the moment, there’s not much we could do to stop it. U.S. missile defense capabiliti­es are also insufficie­nt to stop a large volley of ballistic missiles from an equipped and determined adversary.

Russia demonstrat­ed an anti-satellite weapon test in which a land-based missile was fired at a retired Soviet satellite in low-earth orbit. This prompted the Internatio­nal Space Station crew, including a Russian commander, to temporaril­y take refuge in the Dragon and Soyuz modules given that even pea-size space debris at orbital velocities can rip through metal like superpower­ed mortar rounds.

The senseless test generated thousands of pieces of space debris that will remain in orbit for several years. We have entered an age in which continued careless behavior in space could cripple our modern orbital infrastruc­ture. Recent estimates suggest there are greater than 100 million pieces of human-created debris in Earth’s orbit. It’s not crazy to imagine orbital space as an impassable minefield of derelict satellites and other junk caused by our own malfeasanc­e and neglect.

We also have asteroids to worry about. While scientists believe they have cataloged almost all of the largest “planet-killer” asteroids in our vicinity, there are an estimated 20,000 “medium-sized” asteroids capable of leveling a city, of which we have identified less than half. As part of its Planetary Defense directive, NASA is launching the Double Asteroid Redirectio­n Test, or DART, mission to test a means to redirect an Earth-bound asteroid. We just need to detect them first, and unfortunat­ely, many recent asteroids were not detected until after they whizzed by or, in the case of the 2013 Chelyabins­k meteor, until impact.

These problems need attention now. I imagine the best solutions will involve a mix of diplomacy, internatio­nal cooperatio­n and technologi­cal advances.

We’re doing what we can here at the University of Texas at San Antonio, for example, with a growing aerospace engineerin­g program and the completion of a new hypersonic wind tunnel. Fostering a diverse and technicall­y trained workforce is a good place to start.

But as a country we need to do more. So go outside tonight, look up at the stars and enjoy space. If you time it right, you might see the space station fly by. Because, at least for today, the sky isn’t falling. Let’s try to keep it that way.

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