The Hook. Today’s space digest featured an almost invisible line: "Perseverance captured Phobos transiting the Sun using the Mastcam-Z camera. The image was taken on August 12, 2026, on the mission’s 1,948th Martian sol." Silvio, in his commentary, rightly highlighted this as a warm kernel—"a rover that was supposed to study rocks has quietly become an astronomical observatory." But when I dug into the material, it turned out that behind this photo of a potato-shaped moon gliding across the solar disk lies a five-layer archaeology: the fog of the Potomac in Washington in 1877, through which Asaph Hall searched for Mars’ satellite for twelve nights in a row and couldn’t find it; the first Martian "solar filter," made by an engineer at Malin Space Science Systems for Curiosity’s Mastcam in 2012; forty observations of Phobos transits and eight of Deimos, which helped astronomers refine the moons’ orbits by 25 miles; an orbital reduction of 2 meters per century, due to which NASA scientists in 2015 first acknowledged: Phobos has already begun to break apart, and a new study in A&A in February 2026 showed that it won’t be a simple fall, but a sesquinary catastrophe—debris torn from it will then re-bombard it, finishing it off for good. And finally—the frame from July 2, 2026, sol 1907: Earth, a pixel-sized dot 314 million kilometers away, vanishes behind a lunar body for the first time in human history, captured from the surface of another planet. This is perhaps the most poetic and most engineering-tender work done by a rover that was never designed with an "astronomical mode."
What happened. On August 12, 2026, the 1,948th Martian sol of the mission, NASA’s Perseverance rover pointed its Mastcam-Z camera at the Sun and captured the silhouette of Phobos gliding across the solar disk. The animation, released by NASA on August 24, was "color-enhanced to simulate what a human would see watching the transit from the Martian surface through protective solar glasses." This is not the first Phobos transit for Perseverance, but every such frame is more than just a pretty picture: it’s an astrometric experiment that refines the moon’s orbit.
Details that make this frame special. Phobos is no ordinary moon. It’s the closest natural satellite to its planet in the entire Solar System: orbiting just 6,000 km above Mars’ surface, with an orbital period of 7 hours 39 minutes—about three times faster than Mars itself rotates. Because of this, from Mars’ surface, Phobos rises in the west and sets in the east—the only known case among major moons. Its dimensions are 26 × 22 × 18 km, its shape is potato-like, elongated toward Mars, its albedo is 0.071, making it one of the least reflective bodies in the Solar System (even the asteroid belt is brighter). And most importantly: it’s too small to completely cover the Sun—what we see isn’t an eclipse, but precisely a ring-like transit, "a potato-shaped shadow sliding across the disk."
Quote from the Perseverance team, NASA Science, August 24, 2026:
«Perseverance used its Mastcam-Z camera to capture the silhouette of Phobos as it crossed in front of the Sun on August 12, 2026, the 1,948th Martian day, or sol, of the mission. The animation has been tinted to simulate what a human would see if they were watching the transit from the Martian surface through protective solar eclipse glasses.»
«By comparing the various recordings, scientists can refine their understanding of the potato-shaped moon’s orbit, learning how it is changing. Eons from now, Phobos’ orbit is expected to eventually send the moon toward the Red Planet’s surface.»
Source: NASA Science, "Perseverance Captures Another Phobos Transit," August 24, 2026. [1]
This is a frame I want to highlight separately because it’s more than engineering routine. On July 2, 2026, the 1,907th sol of the mission, Perseverance, using the same Mastcam-Z camera, captured the occultation of Earth by Phobos—that is, Earth, visible as a single pixel-sized dot 314 million kilometers from Mars, disappeared behind the dark edge of the potato-shaped moon, then reappeared seconds later. NASA released this sequence on August 5, 2026, with a phrase that takes the breath away from anyone who’s ever looked at the stars:
«This is the first time humanity has captured from the surface of another planet an observation of Earth disappearing behind an object.»
What makes this frame unique. An occultation (when a larger-appearing body completely covers a smaller one from the viewer’s perspective) differs from an eclipse. NASA spells this out in the release:
«Astronomers call the event captured in this observation an occultation: when a larger-appearing body completely blocks the one behind it from the viewer’s standpoint. By contrast, an eclipse occurs when one object moves into the shadow of another… When the roles are reversed, with a smaller-looking object crossing the face of a larger-looking one, astronomers call that a transit.»
Geometrically, Phobos appeared from Mars to be about one-third the diameter of our Moon as seen from Earth—meaning it was a "large" object covering Earth. Mark Lemmon, Mastcam-Z co-investigator from the Space Science Institute in Boulder, Colorado, who planned the observation and assembled the composite, explains why this wasn’t trivial:
«Phobos crosses the Martian sky three times a day, and Earth is visible for months at a stretch, but catching one directly behind the other takes planning and a little luck.»
And a quote from Justin Maki, Mastcam-Z deputy principal investigator:
«The composite image makes for a unique Earth self-portrait, taken from the surface of another planet, with a Phobos photobomb.»
Source: NASA, "NASA's Perseverance Rover Watches Earth Vanish Behind Martian Moon," published August 5, 2026. [2]
This isn’t just "another photo." This is the first instance in history where humans watch our planet disappear behind something—from another planet. Before this, all our "planetary portraits" were taken either from Earth or by flyby probes. Here, it’s a stationary observer on the surface of Mars, deliberately waiting for two points of celestial mechanics—Earth and Phobos—to converge on a single pixel of its camera.
Here’s where it gets most interesting—why engineers who designed Perseverance to search for traces of microbial life in Jezero Crater built a solar filter into Mastcam-Z, allowing it to look directly at the Sun. The history is longer than it seems.
When Spirit and Opportunity landed on Mars in 2004, the uncertainty in the orbits of Mars’ moons was enormous. Mark Lemmon (then a Mastcam co-investigator for Curiosity, and earlier a member of the MER rover team) recounts in a 2019 NASA publication: the first attempt by Spirit/Opportunity to photograph Deimos against the Sun showed the moon was 25 miles (40 km) off from where it was expected. This meant the orbital models, calculated from Earth-based and orbital observations, had a systematic error that could only be corrected by direct astrometric observation from the surface.
«Before the Spirit and Opportunity rovers landed in 2004, there was much higher uncertainty in the orbit of each moon. The first time one of the rovers tried to image Deimos eclipsing the Sun, they found the moon was 25 miles (40 kilometers) away from where they expected.»
Quote from Mark Lemmon, Texas A&M University / Space Science Institute. [3]
When Curiosity landed in Gale Crater in August 2012, engineers at Malin Space Science Systems had already built neutral solar filters into its Mastcam—"Martian solar glasses." Over the first years of operation, this yielded about 40 observations of Phobos transits and 8 of Deimos from the Martian surface. Each such observation is an astrometric data point, refining the orbital model.
On March 26, 2019 (Sol 2359), Curiosity captured a ring-like transit of Phobos—16 frames showing the potato-shaped moon passing across the Sun without fully covering it. On March 17, 2019 (Sol 2350), Curiosity captured a transit of Deimos—the smaller moon (about 16 km across), appearing as a "tiny dot crawling across the disk."
And one more detail: On March 25, 2019 (Sol 2358), Curiosity’s Navcam cameras captured Phobos’ shadow gliding over the rover during sunset—a dark band passed over the rover, momentarily dimming the light. This is neither a transit nor an occultation—it’s the passage of a shadow (closer to the lunar shadow during a solar eclipse on Earth).
Source: NASA, "Curiosity Captured Two Solar Eclipses on Mars," April 4, 2019. [3]
While rovers refine moon orbits optically, the InSight seismometer did it geophysically. A 2020 study in Geophysical Research Letters (Agupubs.onlinelibrary.wiley.com, doi:10.1029/2020GL089099) describes geophysical observations of Phobos transits—that is, the registration of tidal disturbances Phobos causes in Mars’ crust and atmosphere as it passes over the InSight station. This is an independent astrometry channel: if Phobos’ orbit is slightly different, the tidal pattern on the surface shifts slightly. Source: Geophysical Observations of Phobos Transits by InSight, AGU, 2020. [4]
A separate study at the 2013 General Assembly of the European Geosciences Union states outright: Curiosity’s Mastcam was used as an astrometric instrument to measure the positions of Phobos and Deimos during their transits across the Sun. In other words, a rover designed for geology turned out to be suitable for classical positional astronomy, with an accuracy that ground-based telescopes couldn’t achieve due to Mars’ atmosphere distorting Earth-based observations.
Source: Astrometric observations of Phobos and Deimos during solar transits imaged by the Curiosity Mastcam, EGU 2013. [5]
The big picture. Over twenty years of rover operations on Mars, more direct astrometric observations of Martian moons have been accumulated than in a hundred years of ground-based astronomy. And each new generation of rovers continues this work. Perseverance, which landed in Jezero Crater in February 2021, picked up the baton—and on August 12, 2026, we got another frame that will one day be factored into Phobos’ orbital model.
Now’s the perfect time to tell how it all began. Because what Perseverance is doing today is a direct continuation of work an American astronomer started 149 years ago on the 26-inch refractor of the U.S. Naval Observatory in Washington.
Asaph Hall III (1829–1907), son of a clockmaker from Goshen, Connecticut, left school at 16 to become a carpenter’s apprentice. Later, he enrolled at Central College in McGrawville, New York, where he was taught mathematics and German by Angeline Stickney—the woman he married in 1856. In 1862, Hall became an assistant astronomer at the U.S. Naval Observatory (USNO) in Washington, and in 1875, he was put in charge of the "Great Equatorial"—a 26-inch (66 cm) refractor, the largest telescope in the world at the time, which remained so for nearly a decade.
In 1877, Mars came exceptionally close to Earth, and Hall decided to search for its satellites. According to his own calculations, a moon’s orbit would have to be very close to the planet, and the chances of finding one were very slim. Hall himself wrote: "The chance of finding a satellite appeared to be very slight, so that I might have abandoned the search had it not been for the encouragement of my wife." Angeline Stickney literally made him keep going when he was ready to quit.
Hall began his search in early August 1877. His technique was unusual for the time: he deliberately kept Mars outside the field of view and rotated the eyepiece to scan the entire perimeter around the planet, because the expected moon’s orbit was inside the "halo" of light surrounding Mars’ disk. Hall’s notebook entry (quoted in Wikipedia, citing Morley 1989):
«I repeated the examination in the early part of the night of 11th [August 1877], and again found nothing, but trying again some hours later I found a faint object on the following side and a little north of the planet. I had barely time to secure an observation of its position when fog from the River stopped the work. This was at half past two o'clock on the night of the 11th. Cloudy weather intervened for several days.»
"Fog from the River"—fog from the Potomac. The observatory stood in an area known colloquially as Foggy Bottom—now the heart of Washington. For twelve nights in a row, Hall searched, and every time, fog, clouds, or unstable atmosphere ruined the observations.
On August 17, Hall spotted the outer moon—the one we now call Deimos. He was so sure he told his assistant, George Anderson: "I think I have discovered a satellite of Mars. Tell it to no one." Anderson kept his word—but "the thing was too good to keep," Hall admitted, and he himself "gave away" the discovery.
On August 18, 1877, while waiting for Deimos to reappear in the field of view, Hall saw the inner moon—Phobos. This happened around 09:14 GMT (by modern clocks), though 19th-century sources used the astronomical convention "the day begins at noon," so older records list it as "August 17, 16:06 Washington time."
The names "Phobos" (fear) and "Deimos" (terror) were proposed by Henry Madan, a science master at Eton College, from Book XV of the Iliad, where Ares summons Fear and Flight as he descends to Earth to avenge his son.
Sources: AAS, "This Month in Astronomical History: The Moons of Mars," August 2016. [6]; Wikipedia, Asaph Hall. [7]
Hall received the Gold Medal of the Royal Astronomical Society (1879), the Lalande Prize from the French Academy of Sciences (1878), the Arago Medal (1893), and was made a Knight of the Legion of Honor (1896). There’s a crater Hall on the Moon. On Phobos, there’s crater Hall (5.4 km, in the southern polar region, 80°S 150°E), named after the discoverer.
But Phobos’ largest crater—Stickney (9 km in diameter, almost at the moon’s center)—is named after Angeline Stickney Hall (1830–1892), Asaph Hall’s wife, who didn’t let him give up the search. It was such a powerful impact (modern estimates: a 1–2 km meteoroid hitting the moon at about 6 km/s) that Phobos nearly shattered, and the shockwave still defines its internal structure. The crater was named in 1973 by the WGPSN—Working Group for Planetary System Nomenclature. Source: Wikipedia, Phobos (moon). [8]
So it turns out that when Perseverance captures the potato-shaped silhouette of Phobos against the Sun, Angeline Stickney is invisibly present in the frame—the woman without whom the discoverer would have given up after the second night. Her crater takes up nearly half the moon’s visible surface. This is the most romantic toponymic connection in the Solar System.
Now we come to the main philosophical part of this story. Because everything NASA’s rovers are doing has a final goal: to refine the parameters of the orbit of a moon that is slowly falling toward Mars.
On November 10, 2015, at the annual Division of Planetary Sciences meeting of the American Astronomical Society, Terry Hurford from NASA’s Goddard Space Flight Center presented work that upended our understanding of Phobos. An article on NASA’s website, published the same day, begins:
«The long, shallow grooves lining the surface of Phobos are likely early signs of the structural failure that will ultimately destroy this moon of Mars.»
The numbers. Phobos’ orbit is just 6,000 km above Mars’ surface—closer than any other known moon. Mars pulls Phobos in by 6.6 feet (2 meters) every hundred years. According to 2015 models, the moon should be destroyed by tidal forces in 30–50 million years.
What changed in our understanding. Before 2015, it was thought that the long, shallow grooves on Phobos’ surface were either traces of the impact that created Stickney crater or secondary impactor debris ejected from Mars. Hurford and his colleagues showed that the grooves don’t radiate from Stickney but converge at a focus slightly off from the crater, and these are "stretch marks" that form when Phobos deforms under tidal forces.
Quote from Erik Asphaug of Arizona State University, a co-investigator:
«The funny thing about the result is that it shows Phobos has a kind of mildly cohesive outer fabric. This makes sense when you think about powdery materials in microgravity, but it’s quite non-intuitive.»
And the key statement from Hurford:
«We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves.»
Source: NASA, "Mars' Moon Phobos Is Slowly Falling Apart," November 10, 2015. [9]
This is a fundamentally new view of the moon’s internal structure. Before Hurford’s work, Phobos was thought to be a relatively monolithic body. The new model suggests its core is a "rubble pile", barely held together by its own gravity, surrounded by a layer of dusty regolith about 100 meters thick. Such an object deforms easily under tidal forces—and its surface "cracks" like an eggshell.
In February 2026, the journal Astronomy & Astrophysics published a study by Harrison Agrusa and Patrick Michel from the Observatoire de la Côte d'Azur, France—"Tidal disruptions of rubble piles: The case of Phobos" (arXiv:2602.21912, published February 25, 2026; published version—A&A 706, A353, 2026).
What they showed. The traditional picture: Phobos spirals toward Mars, enters the Roche limit (about 1.6 Mars radii), and there tidal forces tear it apart, forming a ring around Mars—like Saturn’s rings.
Agrusa and Michel showed this is too optimistic a scenario. If Phobos truly has low cohesion (as do small bodies studied by spacecraft—Itokawa, Bennu, Ryugu), then surface material will begin to detach long before the Roche limit:
And the key twist: the detached material goes into orbit around Mars, then returns and slams into Phobos at high speed, knocking off even more material. This is a "sesquinary catastrophe"—the moon is destroyed by collisions with its own torn-off debris.
Quote from the introduction to the published version on arXiv:
«Our numerical simulations demonstrate that Phobos will be destroyed beyond 2 Mars radii if it has a bulk strength similar to those estimated for small bodies recently visited by spacecraft. Based on our results and some additional arguments, we suggest that previous studies on the fate of Phobos have overestimated its strength, and therefore underestimated its tidal disruption distance.»
«We also speculate that if Phobos undergoes some tidal stripping, its ultimate fate may be determined by runaway collisional erosion rather than a pure tidal disruption.»
Sources: Harrison Agrusa, Patrick Michel, "Tidal disruptions of rubble piles: The case of Phobos," A&A 706, A353 (February 2026), arXiv:2602.21912. [10]; Sky at Night Magazine, "Mars will tear its own moon apart," May 3, 2026. [11]
This means the end won’t be a "clean" tidal breakup, but a viscous, multi-stage death—the moon, losing structural integrity, turns into a dense debris belt long before the Roche limit, and the debris re-bombards it, accelerating decay.
This uncertainty—how much Phobos really resembles a rubble pile and what its critical cohesion is—can’t be resolved remotely. For that, we need a sample of its material and direct measurements of its internal structure. That’s exactly what MMX—Martian Moons eXploration, the Japanese Aerospace Exploration Agency’s mission launching in 2026, is designed to do.
MMX will:
Onboard is the rover IDEFIX (DLR/CNES), which will operate on Phobos’ surface and conduct in-situ measurements of regolith mechanical properties. This data will directly calibrate Agrusa & Michel’s models and tell us how quickly the "sesquinary catastrophe" will actually occur.
Source: Sky at Night Magazine, "Mars will tear its own moon apart," May 3, 2026. [11]; Wikipedia, Phobos (moon), Proposed and undeveloped missions section. [8]
This is the deepest layer of the hook. NASA’s rovers, capturing Phobos transits, are doing orbital astrometry that lets us refine the parameters of Phobos’ fall. Agrusa & Michel’s 2026 A&A study showed that with these parameters, Phobos won’t just fall to Mars—it will break apart sooner. And the Japanese mission, launching the same year, will go check how well these models match reality.
149 years of continuous work on a single line: 1877 → 2004 → 2012 → 2018 → 2019 → 2026 → 2031. The American astronomer with a 26-inch refractor, the Soviet Fobos-1 and Fobos-2 in 1988 (both lost on approach), Spirit, Opportunity, Curiosity, InSight, Perseverance—and JAXA’s MMX. Each generation brings a new tool for the same question: when and how exactly will this little potato-shaped moon die?
Returning to the "potato shape"—this isn’t just a casual metaphor. It’s a real physical problem that explains why 19th-century astronomy couldn’t have seen the details Perseverance captures today.
What we know about the origin of Phobos and Deimos. There are two hypotheses, and they explain the moons’ shapes differently.
Hypothesis 1: Captured asteroids. Both moons resemble carbonaceous asteroids from the outer Main Belt (D-type and T-type) in composition and albedo. This hypothesis suggests Mars once captured two asteroids. The problem: both move in very circular, very low-inclination orbits—unusual for captured bodies, which typically follow highly elliptical, chaotic trajectories.
Hypothesis 2: Impact formation from a debris disk. The alternative: a massive impact on Mars ejected a debris disk, from which both moons later formed. This explains the circular orbits and shared chemical composition but requires very specific impact parameters.
Why this matters for Perseverance. If Phobos is a former asteroid, its internal structure might resemble Itokawa, Bennu, or Ryugu—a true rubble pile with very low cohesion. If it’s a fragment of a Martian disk, its internal structure might be more monolithic. This determines the death scenario: a "clean" tidal breakup vs. the "sesquinary catastrophe" described by Agrusa & Michel.
Sources: Wikipedia, Phobos (moon), Origin section. [8]; Sky at Night Magazine. [11]
Back to the engineering question: why did cameras designed to photograph rocks turn out to be useful for astronomy?
Mastcam-Z is a pair of stereoscopic cameras with zoom lenses on Perseverance’s mast. Resolution: 1600×1200 pixels, field of view from 5.6° (zoom, like a 110mm telephoto) to 104° (wide angle). Mastcam-Z has neutral solar filters that can be placed in front of the lens—allowing it to look directly at the Sun without "blinding" the sensor.
This isn’t unique to Perseverance—similar filters were on Curiosity’s Mastcam (MSSS/Malin Space Science Systems, San Diego). And that’s why Curiosity conducted over 40 Phobos transit observations since 2012—this isn’t a side effect of design, but an intentionally built-in "Martian telescope" function.
What NASA engineers got right back in 2003 (for Curiosity/MER), when planning the instruments: they realized that systematic astrometric observation of the moons from the surface is the only way to calibrate orbital models, because:
This is an example of how an engineering solution made for one task turns out to be critically important for another. Mastcam-Z was designed for geology in Jezero Crater. But the same sensor + filter + stable platform on the surface proved to be the perfect tool for astrometry of two moons.
When I first saw the Phobos transit announcement on August 12, 2026, I had the usual journalistic urge—to dismiss it as "a pretty picture of the day." But when I dug into what lay behind it, I found that this frame is a point where seven different stories converge, each interesting on its own, and together they form a very tender engineering-philosophical parable.
The transit itself. Asaph Hall in 1877 was searching for the same moon that Perseverance photographs every few months today. Between them—149 years, five generations of instruments, but the observation remains the same.
Astrometry. Every frame refines the orbit. Forty Phobos transits and eight Deimos transits over Curiosity’s years reduced orbital model uncertainties so much that Spirit/Opportunity in 2004 immediately found Deimos was 25 miles off from where it was expected.
Earth-vanish on July 2, 2026. This is the first-ever image of Earth disappearing behind a lunar body, captured from the surface of another planet. Mark Lemmon planned it; Justin Maki assembled the composite; Perseverance and Mastcam-Z delivered. This isn’t a "bonus"—it’s a new category of astronomical observation.
Phobos’ fate. Falling at 2 meters per century, 30–50 million years until destruction per the 2015 model, sesquinary catastrophe per Agrusa & Michel’s 2026 A&A study. NASA’s rovers are photographing a dying moon, and every frame is data on how fast it’s really dying.
Names. Asaph Hall, Angeline Stickney, Mark Lemmon, Justin Maki, Terry Hurford, Harrison Agrusa, Patrick Michel, Mastcam-Z → MSSS/ASU/SSI. Names that wouldn’t be together without a specific chain of people—and a specific telescope-camera, and a specific foggy Washington night in 1877.
Origin. The potato shape isn’t random. If Phobos is a captured asteroid, its internal structure resembles Itokawa/Bennu/Ryugu (a true rubble pile). That means Agrusa & Michel are right, and catastrophe will come sooner than old models predicted. JAXA’s MMX in 2026 will go check.
Mastcam as a telescope. Curiosity, Spirit, Opportunity, Perseverance—all carry cameras with neutral solar filters that turn a geological tool into an astrometric telescope on Mars’ surface. This isn’t accidental—it’s one of NASA’s best engineering intuitions of the last 25 years.
First, it’s a story about how scientific work never ends. Asaph Hall in 1877 discovered Phobos. Today, Perseverance refines its orbital parameters so Agrusa & Michel can calculate how it will die. In a few years, JAXA’s MMX will fly to Phobos to collect samples and test the models. This is a continuous chain, where each new generation of instruments closes one uncertainty and opens another.
Second, it’s a story about how an engineering decision made "just in case" becomes critically important twenty years later. Neutral solar filters on Mastcam were built into Curiosity’s design in 2003 so Spirit/Opportunity and Curiosity could check moon orbits—and the same set of filters on Perseverance’s Mastcam-Z allowed the first-ever image of Earth disappearing behind a lunar body from another planet’s surface on July 2, 2026. This is the best illustration of how "investing in the tool" pays off over decades.
Third, it’s a story about how a mission’s "side product" becomes the main thing. Perseverance was designed to search for traces of microbial life in Jezero Crater. But it’s been operating steadily since 2021, and over five years has accumulated more astrometric data on Martian moons than all the world’s ground-based telescopes combined over the past hundred years. Any sufficiently long mission becomes something more than it was intended to be.
Fourth, it’s a story about how things die. Phobos is already breaking apart—slowly, by 2 meters per century, but already. The grooves on its surface are "stretch marks" that form when a body deforms under tidal forces. And when, in 30–50 million years, we see (if we’re still watching) a ring around Mars—that will be Phobos’ remains. Right now, in 2026, we photograph its silhouette against the Sun every few months, and every frame is testimony to its slow death.
If I were writing a column, I’d start with Angeline Stickney. The woman who in 1877 told her husband: "don’t give up." Without her, Asaph Hall would have quit after the second night, Phobos would have been discovered decades later, and maybe by someone else—but no one would have known her name. Now her crater takes up half the visible surface of the moon that Perseverance photographs against the Sun every few months, and in 30 million years that moon will turn into a ring around Mars, and in 50 million years that ring will settle onto its surface, and in a billion years Mars will look like Venus—moonless, alone.
And against this backdrop, the composite image from July 2, 2026—Earth, a pixel-sized dot, vanishing behind Phobos, captured by Perseverance’s Mastcam-Z, assembled by Justin Maki, planned by Mark Lemmon—becomes one of the most poetic frames in the history of spaceflight. Not because it’s technically complex. But because it’s the first time we’ve watched our planet disappear behind a foreign moon from a foreign planet. And every second of that disappearance is another stroke in the model that will tell us when the potato-shaped moon with Stickney crater will finally shatter.
This is the engineering beauty of such projects. Cameras designed for rocks become telescopes for dying moons. A rover searching for microbial life quietly conducts orbital astrometry, refining the prediction of a satellite’s death. And all of this is a continuation of the work Asaph Hall began in the Potomac fog on August 11, 1877, seeing a "faint object on the following side and a little north of the planet" before the river fog cut short his observations.
149 years later, we’re still watching the same moon. Only now—from another planet.