Across the Universe: Astronomy domine
This column from The Tablet was first run in December 2018
December 2018 was a busy month in space. The Japanese Hayabusa II mission was orbiting Ryuku, a tiny near-Earth asteroid. A Chinese probe was about to place a lander on the far side of the Moon. NASA's Insight mission had just arrived on Mars to measure marsquakes and the heat flowing from its interior. Virgin Galactic was testing a ship that can take tourists above the stratosphere.
This image shows asteroid Bennu’s boulder-covered surface. It was taken by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on April 11, 2019, from a distance of 2.8 miles (4.5 km). The field of view is 211 ft (64.4 m), and the large boulder in the upper right corner of the image is 50 ft (15.4 m) tall. When the image was taken, the spacecraft was over the southern hemisphere, pointing PolyCam far north and to the west. Credits: NASA/Goddard/University of Arizona
Of all these, my attention was on OSIRIS-REx. (The name is a typical NASA acronym; don’t ask.) This probe had also just arrived at a near-Earth asteroid, named Bennu, with essentially the same mission as Hayabusa II. It was the dream of the late Mike Drake, my first PhD advisor at the University of Arizona; after his death, the science team lead fell to Dante Lauretta, whose PhD director was my MIT classmate Bruce Fegley. And the rest of the science team are also friends of mine.
The holy grail of asteroid science for a long time has been to find asteroids with the same composition as those rare but important meteorites rich in water and carbon. Though science fiction stories talk about mining rare minerals from the asteroids, in fact water and rocket fuel would be what’s most in demand in the near future. Rather than spending fuel to lift more fuel off the Earth to power spacecraft onwards to the planets, it would be much cheaper to make the fuel locally out of materials that are already up there.
Murchison meteorite. This black carbonaceous chondrite does have water. Photo credit: L. Lebofsky.
Allende meteorite slice. This black carbonaceous chondrite doe NOT have water. Photo credit L. Lebofsky.
But how can we know which asteroids have water? And how can we be certain that the material in the asteroid is really the same as the meteorites in our lab? There are many black meteorites in our collections, but only a few of them have the water we’re looking for. Going to a black asteroid is not enough, then; it has to be the right kind of “black.” And even if the color is right we can’t be sure it’s really the stuff we’re looking for. Like ordering a Christmas present on-line, we can’t tell for sure if the picture in the catalog actually matches what we thought we were getting until the package arrives home. Hence, Hayabusa II and OSIRIS-REx chose to test slightly different kinds of dark asteroids; and they both plan to return samples to Earth.
Notice how this science works. We have an idea of what we think we are going to find – we wouldn’t know what to look for otherwise. But whether it is a distant dark asteroid, the inside of Mars, or the far side of the Moon, we won’t really know what’s there until we go there. And nothing beats having a real sample in hand; or, like the space tourists know, being there yourself.
Every culture in history has thought they knew what the gods would be like. Even the ancient Israelites thought they had a clear picture of their God. But only in the Incarnation could we learn first hand, face to face, who this God really was. As it happens, a carpenter’s child in a manger was not what they were expecting; nor was a message of love and forgiveness always welcome to an oppressed people looking for revenge. As with our science samples, we always have to be prepared to be surprised. Sometimes surprises make the best Christmas presents.
And surely God knew what it’s like to be human. But it’s good for us to know that, having been here, He knows first hand.
[All the missions mentioned above have had roaring successes; as of this writing, Hayabusa II has picked up its samples and is en route back to Earth.]
Across the Universe: The New Paganism
The following column was published in The Tablet in November 2009; we ran it again here in 2016. This is the version I finally submitted of the column posted here yesterday...
The fall of the Ensisheim Meteorite, 1492, from the Vatican Library (MS Chigi G.11.36, folio 199v)
You will know the end-times by their signs, we’re told in the Gospel readings at this time of year. Given the nature of those signs, mostly dramatic events in the sky, you can imagine the kinds of questions that are typically addressed to those of us who study meteorite falls. The apocalyptic visions in the Gospels bear a certain resemblance to our understanding of the destruction that an asteroid impact would produce. Is it mere coincidence? Do I have any advice for the fearful? Yes: read the Gospel passages in their context as lessons on how to live, not how we’ll die. Meanwhile, quit smoking and wear your seat belt.
That said, what does science tell us about the end of the world? We know that our solar system has a finite lifetime. Stars like our Sun can only shine for about ten billion years before they run out of nuclear fuel; we are already halfway through that lifetime. We’ve observed other stars “go nova” and explode when the fuel runs out. If it happens to other stars, it should happen to ours.
Could Earth be hit by an object big enough to wipe out most of life on the surface of this planet? An asteroid only a few tens of kilometers across could ignite massive fires where it hit, sending soot into the upper atmosphere to cut off sunlight over the whole earth and freeze us all: Robert Frost’s “fire and ice” both, together. The odds of it happening in any given year are one in a hundred million, but it’s not impossible. Probably something like this happened 65 million years ago when the dinosaurs died. And we know debris from space hits other planets all the time. With even a small pair of binoculars you can see craters on the Moon; most other planets’ surfaces show similar scars. If it happens to other planets, it should happen to ours.
But destruction is not the only thing that can rain from space onto Earth. Comets, asteroids, and meteors may also be the source of the organic materials that are the ingredients of life. How did that raw material turn itself into plants and animals? And could it happen on other planets? If it happened on ours, it should happen to other planets, around other stars.
Those are the topics of the modern science of astrobiology; this past month [November 2009] the Vatican Observatory ran a study week for thirty astrobiologists at the Pontifical Academy of Sciences. Thinking about extraterrestrial life is not at all new for us, or for the church, of course. I can find in our files coverage of such topics in the popular press going back at least fifty years. For that matter, in the late middle ages, Bishop Nicholas of Cusa speculated on many Earths and many suns. And in the scriptures are plenty of references to other non-terrestrial intelligences, from angels to the stars themselves who (Baruch 3:35) sing for joy, telling their Creator “here we are!”
Of course we don’t know yet how life arose, much less how it will die. The astrobiologists have no fear of running out of things to study. To say merely “God does it” is an insufficient answer, reducing Him to nothing more than a new Jove or Ceres. It’s a new paganism. The medieval scholastics understood the difference between primary and secondary causes, and indeed the ancient Hebrew author of Genesis happily adapted Babylonian science while rejecting Babylonian gods. If their cosmologies could handle that, so can ours.
Our concept of “world” – much less its end – is very different now than when Jesus spoke. Yet His message remains potent. Our concepts of heaven and earth may pass away, but his words are no less relevant.
Not Quite Across the Universe: Signs of the Times
Welcome to another re-run; this column first ran here in 2016...
Writing my monthly Tablet columns, I often go through many drafts; sometimes the changes are quite radical. This is an early version of the column I wrote for in the Tablet in November, 2009; but it just didn't feel right, so I kept working at it.. Going through my old columns to publish here at the Catholic Astronomer I discovered that I had kept this version, and I was intrigued by the ideas I was trying to get across... many of which didn't survive the final draft. So I thought it might be amusing to show you what didn't get published.
You will know the end-times by their signs, we’re told in the Gospel readings at this time of year. Couple that with typical Hollywood end-of-the-world films, and you can imagine the kinds of questions that we who study asteroid collisions and meteorite falls get. (Read the Gospel passages in their context; they are lessons on how to live our lives, not when to fear our deaths. If you're afraid of dying by asteroid impact, my advice is to quit smoking and wear your seat belt.)
November 2009 also found the Vatican Observatory in the news, running a study week with 30 astrobiologists who presented their work at the Pontifical Academy of Sciences. With the short-term memory characteristic of most journalism, we at the observatory were inundated by requests for media interviews about the Church’s “new outreach to extraterrestrials.” I can cite at least 50 years’ worth of such popular journalism; for that matter, Bishop Nicholas of Cusa speculated on many Earths and many suns in the 1400s.
Along with the journalists come those earnest amateur philosophers who want to share with us their theories about life and the universe. In the old days, the primary sign of such enthusiastic nonprofessionals was cramped handwriting on onion-skin paper. Nowadays their disquisitions come as e-mails with a certain creativity in the capitalization of letters and words. The more web-savvy authors include numerous obscure but colorful images and diagrams. [And You-Tube links!]
The week after the astrobiology meeting, I personally received two dozen such messages, even though I wasn't even at that meeting. To quote a typical letter, “I have written an article on the parallels between the Holy Trinity, matter, and man… including a possible eschatological implication” – could I please comment? Another gentleman ends his description of the UFO people he’s encountered with the offer, “I am available for research programs to any and all sciences!”
How do we react to these earnest messages? Laughter is tempting but I suspect inappropriate; to the angels, our more professional speculations must appear to be just as ludicrous. Instead, I feel a terrible sadness. These sincere seekers desperately want to participate in the wonderful human adventure of exploring and understanding the edges of our cosmos; who can blame them? Who am I to stop them?
But they don’t know how to join in on the conversation. By trying to publish hypotheses of a kind that normally require years of study (and jumping through academic hoops), they’re trying to crash our party; they haven’t paid their dues. Moreover, they exhibit a certain arrogance to think that they can contribute to a field where clearly they haven’t spent the time to find out what’s already been written by so many generations before us. Those are the dues they haven’t paid.
Even sadder, however, is the presumption that “the right theory” is actually what matters. Rather, it’s more like working out a crossword puzzle; the answer shows if you’ve actually solved it, but once you’ve done it, you can throw it away.
Except, unlike a crossword, science is a team sport. Only in bad science fiction films (and the popular press) do lone misunderstood geniuses make paradigm-shattering breakthroughs. In reality, even if one of those e-mails held a profound truth, it would be useless to the rest of the field. To contribute to the conversation, you have to speak in a context, and a language, that the rest of us can understand.
And surely loving God and neighbor is of more worth than being right about your “trans-dimensional unified field theory.” All our papers and projects will be the first things to be consumed in fire when the Son of Man comes in a cloud with power and great glory.
Tomorrow I'll post the the very different version I sent to The Tablet; see if you agree with me that the second version is better!
Across the Universe: Eye Candy
This column first ran in The Tablet in November 2008; we first published it here in 2016
We were once trying to take images of the centaur Pholus (see the box) and this dreadful galaxy almost got in the way. Image is made of several images taken in different colors, hence the odd colors of the moving object, Pholus
Most people think that we astronomers spend all our nights looking through telescopes at beautiful sights in the sky. The truth, of course, is far more mundane. Most of our days are spent in offices staring at computer screens. And even the time spent at the telescope (for me maybe twice a year, five nights at a stretch) are spent in a control room staring at a computer screen... all night, 3000 meters up a mountain.
Our targets last month [October 2008] at the Vatican Advanced Technology Telescope in eastern Arizona were Centaurs, comet-like bodies whose eccentric orbits carry them from well beyond Neptune to the regions of Saturn or Jupiter. My Arizona and Oklahoma colleagues and I would wake up noon, have breakfast, do a few chores, answer e-mails; then at about 4:30 pm we’d open up the telescope dome and begin the routine of turning on all the systems that make the telescope work: the pumps that maintain the hydraulic fluids on which it turns, the fans that cool the telescope dome, the coolant that keeps the mirror at the same temperature as the outside air.
As the sun set, we’d take test images of the blank sky to show up the dust on the camera chip. (Later, when we’re back down from the mountain, we’ll use these images to correct for the dust shadows on our science pictures.) Then, as the sky would get darker, we’d tune up the alignment and focus of the optics. Finally, about an hour after sunset, we’d steer the telescope to our object and begin to take our data. We’d work until dawn’s twilight, then pack up the telescope and hope to be asleep by 6 am.
Our data were simply images of the same Centaur, taken like a litany again and again, once every three minutes for hours on end. From these we hope to extract the brightness of the body and see how it changes (ever so slightly) over the course of the night. Presumably this change in brightness is connected with how the body’s irregular shape presents itself to us as it spins. Enough of these light curves, taken from enough angles during its orbit, and we can eventually get an idea of the three-dimensional shape of the object. The shape, in turn, tells us about its internal strength and composition, which eventually can give clues to the way it was put together.
Because it can take decades for a Centaur to go through a wide enough part of its orbit to show its shape completely, it may be another twenty years before other observers, taking complementary data, will be able to compare their numbers with ours and complete the shape model. This year’s run may finally be used by astronomers who are, today, just learning to count their toes.
The rhythm of observing is monastic in its regularity, and there is a certain peace that comes from this work high on a mountain top. But occasionally we'd take a short break from our Centaurs, and turn the telescope to some more spectacular objects: the Horsehead Nebula; the Helix; the galaxy NGC 2903. We'd take tourist pictures – three quick snaps, one in each colored filter. Then it was back to work.
Just another gratuitous pretty astropicture, in this case, the Horsehead Nebula as imaged at the Vatican Advanced Technology Telescope.
Seeing these pretty swirls of light, rather than just the same collection of dots, helped boost our spirits: a little instant gratification to remind us why we’d gotten interested in astronomy in the first place. And the pictures, now processed in color, will grace future books and publicity materials to help show off the Vatican Observatory and its telescopes.
Astronomers do not live by bread alone. A little candy for the eye helps sweeten the soul.
Across the Universe: Clouds of Unknowing
It's not everyone you know who gets their own biography... written for kids!
(This column first appeared in the Tablet in November 2006; we first ran it here in 2015)
When she first knew me, I was a rabbi; Heidi played drums in the band. It was a production of Fiddler on the Roof at MIT, where I was a lecturer and she a student – in fact, she wound up taking a course from me. Six years later, I had entered the Jesuits and she, with a newly minted PhD, had a job at the Jet Propulsion Lab helping guide the Voyager spacecraft towards Neptune. Then Comet Shoemaker-Levy hit Jupiter, and she was the scientist in charge of the Hubble images of the event...
Data: H. Hammel, MIT, and NASA. Processing: Judy Schmidt. Shoemaker-Levy 9 Fragments D and G impact scars on Jupiter. NASA image from the Planetary Society website
In 2006, Dr. Heidi Hammel was in my classroom again, but this time as a lecturer. That year [2006] found me at Fordham University, in the Bronx, filling the Loyola Chair for visiting Jesuit scholars. It’s not far from where Dr. Hammel now lives and works. We’d run into each other at a meeting recently, and she had agreed to tell my astronomy class – and me – the latest about her research into Uranus and Neptune, the giant ice planets in the outer solar system.
The Voyager spacecraft had visited Uranus and Neptune some 20 years ago, revealing a fascinating set of moons around each of them; but the planets themselves, to our eyes, had seemed rather bland. Uranus itself was revealed to be so featureless that JPL’s favorite press release photo was just an artistic crescent, snapped after the spacecraft had passed. So it was a great surprise when Heidi had spotted a recent poster on some of the newly discovered moons of Uranus; the planet they were orbiting looked odd.
She asked the moon-hunters about it. They had used the Hubble telescope to image the moons, overexposing Uranus in the process, so they took one more image of Uranus at proper exposure just to add it to their poster. They hadn’t noticed what she noticed: in the fifteen years since Voyager, Uranus had developed clouds so big that even a telescope on Earth could see them.
The 1998 images of the rings with the image of Uranus and its clouds. JPL/NASA
That started a five year project for her, imaging the Uranian cloudtops with the world’s-largest Keck telescope in Hawaii; with adaptive optics twisting its mirror to counter the twinkling of Earth’s atmosphere, Keck outperforms Hubble and matches all but the closest spacecraft images.
Not only does Uranus now have clouds; a whole new set of brighter clouds have appeared over the southern hemisphere in just the past year. They are changing our thinking about how its atmosphere (and planetary atmospheres in general) behave. Understanding them, may some day help us understand climate change here on Earth. And the clouds are telling us about the planet beneath the clouds, the thick slurry of ice and gas that has never been seen directly.
We’d only seen Uranus close up, with a spacecraft, once. When it appeared boring at that moment, we never gave it another look. We were wrong. Appearances are deceiving, especially if we allow ourselves to be deceived. Uranus was no more a boring, unchanging planet any more than I was really a rabbi; we were fooled by the outfit it happened to be wearing when we first encountered it.
Heidi has seen me many times over the years, mostly in the regular scientist’s uniform of tee-shirt and jeans. This past week, she also saw me in full clerical garb, what I wear when teaching science to undergraduates. As she packed up her computer and briefcase to head back home (and rescue her kids from daycare) I asked her if she was surprised to see me in a clerical collar.
“Oh, no,” she said. “I’m used to it. My mom wears one all the time.”
I never knew; her mother is a Lutheran minister. Even after twenty years, we can still learn new things about old friends.
(The 2011 Special Edition of the magazine Argentus, edited by our friend Steve Sliver, was dedicated to planet Neptune; it included an interview of Heidi by me.)
ⓜ Free Man in Paris… Diary of 12 November, 2019
I love Paris in November. It’s cool and uncrowded, and it feels like a real city not just a tourist site. I traveled there last week, via sleeper train with a private cabin: the introvert’s delight!
You know, I'd go back there tomorrow but for the work I've taken on
Our stats this month: As of today, we have 145 paid subscribers (two new subscribers since last month — thanks and welcome!) and 9347 people (about a 150 new ones!) who get notified of new postings. We continue to grow, but not nearly fast enough to keep us in business. (Our goal is to have a thousand paid subscribers… at this rate we’ll hit that goal around the year 2045; that at least will still be before my 100th birthday.)
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So, while in Paris I ran into three famous authors, a bunch of scientists, and one or two bits of art. But then, the previous week I’d been to Scotland to “Grasp the Nettle”, and that was equally intense. (And cold and rainy.) But that’s not the only thing I’ve been up to…
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Across the Universe: The competent man
This column first ran in The Tablet in October 2018
When was the Golden Age of science fiction? To quote sf fan Peter Graham, it’s “twelve.” But certainly science fiction came into its own during World War Two and its aftermath when John W. Campbell edited Astounding Stories. Alec Nevala-Lee’s new book, Astounding, provides a fascinating look at Campbell and three of his most notable authors: Isaac Asimov, Robert A. Heinlein, and L. Ron Hubbard.
When I was twelve I was a passionate consumer of their stories, anthologized and conveniently shelved in our public library just outside the children’s section. Even then I knew these stories were silly, if fun. What I never appreciated at the time was how this genre would come to dominate our culture.
One striking insight of Nevala-Lee’s excellent book is how those early science fiction stories praised the engineer as “the competent man.” The way they glorified competence perhaps reflected the fact that most of the authors were themselves incompetent at anything other than spinning fictions. Campbell was an MIT drop-out. Heinlein, discharged from the US Navy for poor health, was a failed politician. Hubbard was a disaster as a Navy officer. Only Asimov succeeded in science, earning a doctorate in biochemistry; at that point, he wrote mostly books of science fact, not fiction. But hundreds of thousands of readers every month, many of them engineers, saw in Astounding Stories their own lives and work depicted as a part of a great and enviable adventure. Wrapped around that, though, came the myth of the single bold inventor standing against an unappreciative and ignorant public.
A sad revelation is just what awful people those writers were. All had terrible relationships with women; not only bad marriages, but (especially Asimov) reprehensible public behavior. Campbell was an overt racist and, not withstanding his support of Asimov, an antisemite. Heinlein at least tried to rise above the racism of the times, but in his stories women are at best 1940’s clichés and at worst… best not described here. And Hubbard was a habitual liar, a character flaw that at least provided him a living as a fiction writer.
Surprisingly, while they all loudly rejected theism (and mocked fellow SF writers like Anthony Boucher, who was Catholic), religious themes and imagery permeate their work. Even Asimov, the non-practicing Jew, wrote a best seller explaining the Bible. Heinlein had a recurring character named Lazarus Long; Hubbard wrote stories of “old Doc Methuselah.” Eventually Hubbard even started his own religion, Scientology, with Campbell as an early advocate. They depended on religious tropes and language.
It seems that the more they rejected traditional theisms, the more they felt the need to create their own. By the 1950s, Campbell fell into a gnostic search for secret knowledge, ranging from Dianetics to perpetual motion machines to a search for psychic powers. The quality of stories he published began a long decline… though in the early 1960s he serialized Frank Herbert’s epic semi-religious space opera, Dune. (Meanwhile, Anthony Boucher went on to found the Magazine of Fantasy and Science Fiction, which soon supplanted Campbell’s magazine as the premier outlet for the genre.)
But beyond atomic power and spaceships, the most enduring invention of golden age science fiction remains the myth of the competent man. Jobs, Zuckerberg, Musk… any of them could have stepped off the pages of Astounding Stories. Like all myths, it is inaccurate and incomplete. But it also creates its own truth, shaping the way we understand our brave new technological world.
Across the Universe: Featureless Features
At the end of September 2016, Rosetta finally ended its mission by crashing into its comet. This column, about an earlier aspect of the Rosetta mission, first appeared in The Tablet in October 2010; we first ran it here in 2016.
ESO image of asteroid Lutetia, via wikipedia
Back in July [2010], ESA’s Rosetta spacecraft, en route to a comet rendezvous in 2014, flew past asteroid Lutetia, a 100 km pile of rock orbiting between Mars and Jupiter. The result of that encounter was a hot topic of both the European Planetary Science Conference in Rome in September and a meeting of American planetary astronomers in Pasadena in October [2010].
Studying asteroids has always been challenging. Even in the largest telescopes they’re mere dots of light, too small to show any shapes, much less surface details. We can only infer their nature from the most subtle of hints: how their brightness varies as they spin, how much infrared light they radiate, their visible and infrared colours.
Minerals that contain iron oxide or water reveal themselves by the specific wavelengths of light they absorb. Sorting by colour and brightness, astronomers in the 1970s were able to work out general classes of asteroids analogous to meteorite types: light, reddish “S” asteroids looked like stony meteorites, while darker “C” asteroids were like carbon-rich meteorites.
But Lutetia was brighter than an S-class asteroid, yet its spectrum was flat. It did not absorb light in any of the characteristic colors. The absence of spectral features was its most revealing feature; our only evidence was an absence of evidence.
Our first guess was a surface of pure metallic, unoxidized, iron... perhaps the metal core of a highly evolved planetoid. Thus Lutetia became the case example of a new “M” class of asteroids. But other, very different possibilities were suggested. Maybe it was a primitive mix of very dark low-temperature material with very high-temperature white inclusions -- the famous meteorite Allende was just such a mixture, albeit more dark than light. Likewise the mineral enstatite, made of the common oxides of magnesium and silicon, has no iron and so no absorption features; and there is also a class of enstatite-rich meteorites.
Then, in the mid 1990s, spectra in the infrared showed that at least one side of Lutetia contained minerals that had reacted with, and incorporated, water. None of previously suggested meteorite analogues contain water. This turned all our ideas upside down; the discoverer suggested Lutetia should be given a new classification -- not “M” but “W”.
We’ve since bounced radar waves off Lutetia’s surface. It reflects those waves with more power than typical rock, but less power than a metallic surface would.
So what is Lutetia? Now we’ve sent a robot there; and we still don’t know. Rosetta’s images show Lutetia covered with a thick layer of soil, complete with landslides and a series of grooves like those seen on the dark, primitive moons of Mars. But Lutetia’s surface is not dark. Furthermore, its density (also measured by Rosetta) is much higher, more than any other asteroid. It might be a well compressed chunk of stone; or it could be a very loosely accumulated collection of iron shards covered with rocky dust.
Meanwhile, the Japanese, who recovered a probe from asteroid Itokawa (see Across the Universe, 26 June), are being tight-lipped about what they found inside. I suspect that means they found nothing; they didn’t get a piece of the asteroid. Indeed, since 1991 space probes have visited 11 asteroids; we still don’t know what any of them are made of.
[In fact, they did find many tiny grains of dust with the chemical composition of LL class meteorites.]
It may take a crewed mission to an asteroid to answer the question unambiguously. Small asteroids approach Earth all the time; they’d be easier to reach, and return from, than the Moon or Mars.
Humans have a long history of attempting to deduce the unseen from indirect evidence, and our answers have always been ambiguous and contradictory. Ultimately its resolution arrives only when we confront the universe, face to face. We will not know the asteroids, till we become asteroids ourselves.
Across the Universe: A Damp Kaboom
This column first appeared in The Tablet in October 2009; we first ran it here in 2016
“Where’s the kaboom?” asked my friend, imitating the whiny voice of the cartoon character Marvin the Martian. “There was supposed to be a Moon-shattering kaboom!”
From the BBC, this image shows the material spilled out by the impact of the NASA LCROSS lunar orbiter in 2009
We were watching live television coverage of NASA’s LCROSS lunar orbiter impacting into a dark crater on the Moon. The idea was that water ice might be hidden in the shadows of craters like this one, set in a region of the Moon’s south pole where sunshine never reaches. Water vapor from all the comets that have hit the Moon over the last four billion years might be trapped and frozen there. By slamming a rocket into those shadows, a giant plume of rock and ice would be lifted out of the shadows and into the view of the nearby spacecraft, and telescopes on Earth.
Or so proclaimed the hyperactive NASA press office. In fact, at the impact, only a faint infrared blip was visible in the spacecraft images. News commentators who had earlier joked about America bombing the surface of the Moon now complained that the promised show was a dud.
Water on the Moon was in the news a lot that month [October 2009]. At the annual meeting of the Division for Planetary Sciences of the American Astronomical Union, astronomers reported on the startling findings from the Indian Chandrayaan lunar orbiter that their infrared mineral mapper had seen the distinctive absorption colors of water near the poles. Scientists from the Cassini and Epoxi probes, who had calibrated their cameras by pointing them at the Moon (en route to their primary targets of, respectively, Saturn and Comet Hartley 2) checked their data and found that they’d seen lunar water, too.
But the total water seen amounts to less than a drop in a liter-sized bucket. In fact, that water feature had long been seen in the lunar samples returned by Apollo nearly 40 years ago. But everyone had assumed they were just seeing the contamination of samples measured in the humidity of Houston, Texas.
Contamination is a constant worry when one travels to places where no human has gone before. While it seems odd to worry about the destruction wrought by a puny human rocket booster on a lunar surface constantly cratered over four billion years by nature’s massive impacts (the Nasa rocket made a hole less than a hundred feet across), even the introduction of one tiny sample of terrestrial microbes onto Mars could forever cloud the issue of whether any life we find there is actually native to Mars, or brought in by a momentary slip in the sterilization of the spacecraft from Earth.
Tracks made by the Spirit rover on Mars; NASA image via Wikipedia
And I appreciate the worries about humans defiling the landscape. I shudder at the sight of ATV tire tracks in the Arizona desert even while I feel a thrill at seeing the same sort of tracks across the surface of Mars. It’s easy to sneer at those who find some scientific excuse to fulfill their adolescent urge to make a Moon-shattering kaboom. It is also easy to sneer at the nannies who would scold us for making such loud bangs.
It is a human urge to make a mark on the universe. Some respond with art; others with graffiti. Some of us write letters to the editor; others, scientific treatises. Yet our every breath – and eventually our decaying dead body – leaves a carbon footprint on the planet. We do not redeem, by ourselves, the cost of our existence.
Meanwhile we spend our lifetime looking, often fruitlessly, for evidence of another’s presence. We still thrill at even the slightest hint of what we’re looking for. And we hope we aren’t contaminating that search with our own traces. Absence of evidence is not evidence of absence; but it may be evidence that we’re looking the wrong way, or in the wrong places.
Across the Universe: Stellar Round Up
This column first appeared in The Tablet in October 2008; we first ran it here in 2016
Okie Tex in the Dark
Black Mesa, Oklahoma sounds like the setting for a Hollywood Western. It looks like one, too. Every year at the Okie-Tex Star Party, three hundred amateur astronomers camp out for a week with their telescopes there, in hopes of dark dry skies. Some of their “amateur” instruments are larger in aperture than the telescopes of the Vatican Observatory in Castel Gandolfo. The miracle of computerized fabrication and the modern Dobsonian mount (a way of holding a telescope in place that replaces complex hardware with simple Teflon pads) has brought the cost of quality optics to the point where the price of a large telescope can be less than that of a small automobile.
My GPS unit directed me as far as Boise City, two hours north of Amarillo, Texas; after that, I was following roads too small for most maps. I was there to give a series of talks during the afternoon and evening hours, entertainment insurance for the campers in case the skies did not cooperate. But that insurance was not needed; the three nights I spent there, the skies were spectacularly clear. Dark skies? That is in fact a misnomer. When there are no cities for hundreds of miles, the Milky Way alone shines so brightly that it actually casts a shadow. You can walk among the telescopes without bumping your neighbor or losing your way.
Wikipedia provided this nice view of the gegenschein, which appears in this image as a bright spot on the diagonal band (running top left to lower right) above the Very Large Telescope in Chile.
The enthusiasts sharing their telescopes with me were knowledgeable, if not professional. “Look, along the ecliptic, directly opposite the point where the Sun lies; around midnight, you can see sunlight reflected back to us from the dust of the asteroid belt,” one friend pointed out to me. “It’s called the googenshine!” Actually, that’s gegenschein; but I didn’t correct him. I had studied it in graduate school; I knew how to spell it, and what the German words mean. But unlike my friend, I had never actually seen it before.
A lot of professional astronomers never look at the night sky; some of them don’t even know how to find the most basic constellations. Even those of us who came to our professional calling from a teen-aged enthusiasm with small telescopes now spend most of our outdoor nights on high mountaintops: the thin atmosphere there can mean clearer images for our instruments, but it deprives our human eyes of the oxygen we need to see the stars in their full glory.
All sorts of analogies come to mind comparing the world of astronomy with religion. We know theologians whose inability to see the living God makes them seem oxygen deprived. We've met the simple believer who couldn’t spell hamartiology but who knows sin when they see it. And yet, the amateur astronomers were delighted to have a few professionals among them (I wasn’t the only speaker there) to enrich their enthusiasm. I suspect we were made more welcome, and listened to more closely, than most theologians visiting a parish would be.
My first night there, a bright flash lit up the sky and caused the observers to howl as their dark-adapted vision was momentarily destroyed. “Turn off the car headlines!” one of them shouted. It was, in fact, a bolide – a tumbling meteorite lighting up the sky as it burned away in the upper atmosphere. Such fireballs occur several times a month across the Earth. That same week, for the very first time, the fall of one such bolide was actually predicted. The professionals had discovered a meteoroid orbiting near Earth just a few days before it struck, and they successfully calculated its fall over the Sudan.
If pieces of either event actually survived to hit Earth as meteorites, it will probably be a posse of amateurs who will round them up. But it will be up to the professionals to judge the samples.
ⓜ The day I almost met Buzz… Diary of 11 October, 2019
Buzz Aldrin, back when travel was easier for him
So, this week I was supposed to meet Buzz Aldrin. It didn't happen, but how it almost happened is a story. And it reminds me of all the other famous (and almost famous) that I met (or almost met)...
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Now, on to the story telling, involving number of Nobel Prize Winners including one who taught at our Vatican Observatory Summer School not long ago (incidentally, there's still time to apply to the school, here ), some well known writers, and various Popes and Presidents, each of them with a story...
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Across the Universe: Asking the right questions
This is the book that my chapter eventually appeared in...
This column ran in The Tablet in October, 2007; we first ran it here in 2015
My first scientific paper, more than thirty [forty!] years ago, was a review of the icy moons of Jupiter. Knowing only the mass and volume of the moon Europa and the evidence of its bright surface, I calculated that Europa’s density matched a mixture of rock and ice, with enough rock (90%) that its natural trace radioactivity would, over the age of the solar system, melt the ice. Europa, I asserted, should have a shiny thin ice crust, a moon-like rocky center, and a liquid ocean water between the two. I even speculated about creatures swimming in that ocean.
An old drawing from NASA hypothesizing its interior; but not as old as my models!
Then the Voyager and Galileo spacecraft arrived and mapped that moon, showing the kinds of cracks expected for ice overlaying an ocean. And Europa deflected Jupiter’s magnetic field just like a salty, electrically conductive ocean might do. Now I’ve been invited to co-author the lead chapter on a new book about Europa. Because of my scientific expertise? No; those spacecraft also revealed how naive my models were. My chapter is a historical overview.
When did people first speculate about Europa’s interior? My models were based on data that had been around for a long time before my 1975 thesis; was I really the first to fish for life in its interior? From my perch on the scrap heap of history, I’ve been inspired to paw through the Vatican Observatory’s library, looking up references back to the early 19th century.
Europa’s mass was calculated by Laplace in 1805, a brilliant analysis of how Jupiter’s moons tweak each others’ orbits. But he didn’t actually determine how many kilograms of stuff could be found inside Europa; he only reported the ratio of its mass to Jupiter’s. Did he know the mass of Jupiter? He should have; it can be computed from the satellites' orbits (which he had just analyzed), the distance to Jupiter (derived from transits of Venus, observed in the 1760s), and an estimate of the Universal Gravitational Constant (reported by Cavendish in 1798).
Yet he never made that calculation.
Europa’s size was measured in several different ways during the 19th century. Angelo Secchi, the Italian Jesuit who first spied the dark canali of Mars and classified stars by their spectra, published a booklet about the solar system in 1859 with the masses and volumes of Europa and the other moons.
But he, too, never bothered to calculate a density from those numbers.
In 1879, Edward Pickering measured the relative brightnesses of Jupiter’s moons. Europa had the brightness of ice but the density of rock, whereas Ganymede and Callisto were as dark as rocks, with the density of ice. But he didn’t make the connection between brightness and density. My melting models (heat from the rocks melted Europa, producing a clean icy surface; icy Callisto didn’t melt) solved a puzzle that he never noticed.
Laplace, Secchi, and Pickering were giants. Why didn’t they do what I did, a hundred years later? It never occurred to them to ask the right question. (In my case, the “right question” came from my thesis advisor, John Lewis.) They saw Europa as a spot of light in a telescope. It takes imagination to realize that it’s also a whole world, with its own history and geology.
Indeed, the questions are often more important than any simple answer, once they change the way you look at the universe. What did they think the moons were? The question could have been as shattering as the one Peter heard Jesus ask: Who do you say that I am?
Of course, even with the right question, you can still get the wrong answer. In 1908, Pickering finally noticed the low densities and bright surfaces of these bodies. His conclusion? Not ice-covered rocks, but piles of white sand!