In case you missed them, here’s a few new pieces I’ve written and published for The Hill, Scientific American, and Quanta magazine over the past month. Thanks as usual to all of my excellent editors. I’m only posting brief excerpts here, so please check out the whole thing using the links below.

 

Space, like the oceans, is not too big to become polluted or for ships to engage in conflict

The private space industry is poised to continue growing, from developers of space tourism and innovative satellite applications to moon developers, Mars colonists, and asteroid miners. Many of the big players so far are based in the U.S., yet policymakers (and international diplomats, too) have already fallen behind are struggling to catch up.

We’re in dire need of a single national organization dedicated to authorizing and regulating activities in orbit and beyond. Congress has the opportunity right now to take a step in that direction but only if it considerably improves upon the currently drafted American Space Commerce Free Enterprise Act.

The version that overwhelmingly passed the House on April 24 promotes the industry and satisfies the Trump administration’s goals, but it lacks bite. It calls for expanding the Office of Space Commerce — which currently only has a few staff members — to license spacecraft, but it’s not clear it would be up to the task or would offer more than rubber stamps on every rocket…

[Read the entire review in The Hill, published on 15 May.]

 

Decades-Old Data Unveils Plumes Spewing from Europa

Archived observations from NASA’s Galileo spacecraft all but confirm the Jovian moon’s subsurface ocean is within reach of future life-seeking missions.

Ever since 2012, when astronomers using the Hubble Space Telescope first spied inconclusive hints of watery plumes emanating from the subsurface ocean of Jupiter’s large, icy moon Europa, space scientists have fiercely debated the claim. Previous estimates had suggested the moon’s crust might be tens if not hundreds of kilometers thick—too thick, that is, to allow direct exploration of its potentially life-friendly ocean anytime soon. A plume venting some of Europa’s ocean water into space where it could be sampled by an orbiting spacecraft would change the whole equation—it seemed, in short, too good to be true.

Now, however, a new analysis of 21-year-old data from NASA’s Galileo spacecraft, which orbited Jupiter from 1995 to 2003, has found strong independent evidence in favor of the plume.

This discovery all but confirms Europa should be considered a high-priority peer of another “ocean world” in the outer solar system, namely Saturn’s moon Enceladus, which also sports an even more dramatic plume. The finding also bolsters hypotheses that posit parts of Europa’s crust are far thinner and more fractured than previously believed—conditions that may allow life-sustaining energy as well as exploratory robots easier entry into the moon’s lightless abyss. Xianzhe Jia, a University of Michigan space scientist, and his colleagues published their findings on May 14 in Nature Astronomy.

“Up until this paper, I was very skeptical that the plume existed, because all those Hubble measurements made before were at the sensitivity limit of the instruments. But this has made me a believer,” says Morgan Cable, an astrochemist at the NASA Jet Propulsion Laboratory who was not involved in the research…

[Read the entire article on Scientific American, published on 14 May.]

 

A Radically Conservative Solution for Cosmology’s Biggest Mystery

Two ways of measuring the universe’s expansion rate yield two conflicting answers. Many point to the possibility of new physics at work, but a new analysis argues that unseen errors could be to blame.

Cosmologists have wielded every tool at their disposal to measure exactly how fast the universe is expanding, a rate known as the Hubble constant. But these measurements have returned contradictory results.

The conflicting measurements have vexed astrophysicists and inspired rampant speculation as to whether unknown physical processes might be causing the discrepancy. Maybe dark matter particles are interacting strongly with the regular matter of planets, stars and galaxies? Or perhaps an exotic particle not yet detected, such as the so-called sterile neutrino, might be playing a role. The possibilities are as boundless as the imaginations of theoretical physicists.

Yet a new study by John Peacock, a cosmologist at the University of Edinburgh and a leading figure in the cosmology community, takes a profoundly more conservative view of the conflict. Along with his co-author, José Luis Bernal, a graduate student at the University of Barcelona, he argues that it’s possible there’s no tension in the measurements after all. Just one gremlin in one telescope’s instrument, for example, or one underestimated error, is all it takes to explain the gap between the Hubble values…

[Read the entire article on Quanta magazine, published on 1 May.]