“Solitude” by Enceladus







“Rolling Stones Rock” Is the Coolest Mars Rock That Ever Rolled

The legendary British rock band has been honored by NASA with a rock that the InSight lander rocket-blasted across the Red Planet’s surface last year.


Those of you who frequently read my articles will know that I have a fascination with rolling rocks on celestial bodies. There’s the numerous boulders on the Moon that have been dislodged and rolled down crater sides, leaving their bouncy imprints in the dirt. There’s also the rolling rocks of Ceres. And the theorized rock tracks that are carved into Phobos. Then there’s Mars, the undisputed king of rolling boulders, imaged to beautiful precision by our orbiting armada of spacecraft.

The most famous rolling rock is no boulder, however; it’s barely larger than a golf ball—but it’s now the most famous pebble in the solar system. It’s a little rock that was minding its own business until a car-sized NASA robot rumbled through the Martian skies on Nov. 26, 2018, retro-rockets firing to slow its descent to the ground, that flipped the innocent ruddy bystander three feet (1 meter) from the landing site. It’s sobering to think that that rock probably hasn’t been disturbed for millions of years until that fateful day.

Behold, the “Rolling Stones Rock,” named after rock legends The Rolling Stones and announced tonight by Avengers actor Robert Downey Jr. to tens of thousands of Stones fans at the Rose Bowl Stadium, just before Mick Jagger, Keith Richards, Charlie Watts, Ronnie Wood, and friends rocked Los Angeles to its core. Space exploration doesn’t get much more Hollywood than this:

And a little animated introduction to the rock itself:

“The name Rolling Stones Rock is a perfect fit,” said Lori Glaze, director of NASA’s Planetary Science Division in Washington, in a statement. “Part of NASA’s charter is to share our work with different audiences. When we found out the Stones would be in Pasadena, honoring them seemed like a fun way to reach fans all over the world.”

While, in the grand scheme of things, naming a little rock after The Rolling Stones may not seem like such a big deal (and, besides, it’s an unofficial designation), as my wife and I stood watching the Stones do a blistering performance of “Sympathy For the Devil”, the family next to us were discussing Mars asking what the InSight lander was doing on the Red Planet.

So, mission success, NASA. Mission success.

“Cross-pollinating science and a legendary rock band is always a good thing…”

Robert Downey Jr.

There’s Something Massive Buried Under the Moon’s Far Side

And it’s likely the massive metallic corpse of an ancient asteroid

This false-color graphic shows the topography of the far side of the Moon. The warmer colors indicate high topography and the bluer colors indicate low topography. The South Pole-Aitken (SPA) basin is shown by the shades of blue. The dashed circle shows the location of the mass anomaly under the basin. [NASA/Goddard Space Flight Center/University of Arizona]

It may be Earth’s only natural satellite and our closest alien world, but the Moon still hides a multitude of mysteries under its surface—including something massive embedded in its far side.

As detailed in a new study published in the journal Geophysical Research Letters, researchers led by Baylor University analyzed data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission that orbited above the lunar surface for a little under a year in 2012.

The two GRAIL spacecraft flew one in front of the other, precisely measuring the distance of their separation in order to detect very small fluctuations in the Moon’s gravitational field. When the spacecraft passed over a region of higher density, the local gravitational field would become enhanced, slightly accelerating the leading spacecraft (called “Ebb”) before the trailing spacecraft (“Flow”) experienced that acceleration. By mapping these acceleration fluctuations, scientist have gained an invaluable understanding of density fluctuations deep below the Moon’s surface that would have otherwise remained invisible.

During this recent analysis, the researchers discovered a gravitational “anomaly” beneath the South Pole-Aitken basin—a vast depression on the lunar far side spanning 2,000 miles wide and several miles deep. This anomaly represents a huge accumulation of mass hundreds of miles below the basin.

“Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That’s roughly how much unexpected mass we detected,” said Peter B. James, of Baylor University and lead author of the study, in a statement.

How did all that material end up buried inside the Moon’s mantle? The South Pole-Aitken basin was created four billion years ago in the wake of a massive asteroid impact. In fact, the basin is known to be one of the biggest impact craters in the solar system. If this crater was formed by an impact, it stands to reason that the gravitational anomaly is being caused by the dense metallic remains of the massive asteroid that met its demise when the Earth-Moon system was in the throes of formation.

“When we combined [the GRAIL data] with lunar topography data from the Lunar Reconnaissance Orbiter, we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin,” added James. “One of the explanations of this extra mass is that the metal from the asteroid that formed this crater is still embedded in the Moon’s mantle.”

There may be other explanations, one of which focuses on the formation of the Moon itself. As the lunar interior cooled after formation, the large subsurface mass could be an accumulation of “dense oxides associated with the last stage of lunar magma ocean solidification,” the researchers note.

The metallic corpse of an ancient asteroid is the leading candidate, however, and computer simulations carried out by the team indicated that if the conditions are right, the dense iron-nickel core of an asteroid can be dispersed inside the Moon’s mantle where it remains embedded today without sinking into the lunar core.

Although there were certainly larger asteroid impacts throughout the history of our solar system, the Moon’s South Pole-Aitkin basin is the largest preserved impact crater known, making it a prime candidate to study ancient impact sites

“[It’s] one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today,” said James.

It just so happens that we currently have a mission at the basin, exploring this strange and unexplored place. On Jan. 3, the Chinese Chang’e 3 mission achieved the first soft touchdown on the lunar far side, landing inside Von Kármán crater and releasing a robotic rover, Yutu-2, to explore the landscape. At time of writing, the mission is ongoing.

Ten Years Later: The Cosmos Remembers Brian the Bat




Wikipedia recognizes Brian’s sacrifice.



A Legend Is Born



And that bat’s name was Brian.






But his legacy would live on.










Eerie Timing, ESO








The NASA mission looks like it’s getting comfortable in Elysium Planitia.









But what about that selfie? Well, here you go:

InSight says hi! [NASA/JPL-Caltech]



Voyager 2 Has Left the (Interplanetary) Building

The NASA probe was launched in 1977 and has now joined its twin, Voyager 1, to begin a new chapter of interstellar discovery

Both Voyager 1 and 2 are sampling particles from the interstellar medium, becoming humanity’s furthest-flung missions into deep space [NASA/JPL-Caltech]

Carolyn Porco, planetary scientist and lead of the NASA Cassini mission imaging team, probably said it best:

Voyager 1 made us an interstellar species; 6 yrs later, Voyager 2 makes it look easy. While these are historic, soul-stirring achievements, I am most happy right now that Ed Stone, the best Project Scientist who ever lived, lived to see this moment. 

via Twitter

It can be easy to lump today’s announcement about Voyager 2 entering interstellar space as “simply” another magnificent science achievement for NASA — but that would be too narrow; the Voyager spacecraft have become so much more. They represent humanity at our best; our will to explore, our need to push boundaries, our excitement for expanding the human experience far beyond terrestrial shores. They also act as a means to understand the sheer scale of our solar system. And what better way to measure that scale than with a human life. 

Ed Stone started working on the Voyager Program in 1972 as a project scientist. Now, at 82 years old, he’s still working on the Voyagers nearly half a century later as they continue to send back data from the frontier beyond our solar system. When we start measuring space missions in half-centuries, or missions that have lasted entire careers, it becomes clear how far we’ve come. Not only does NASA build really tough space robots that surpass expectations routinely, returning new discoveries and revelations about the universe that surrounds us, the Voyagers have become a monument to the essence of being human, something with which Stone would probably agree.

Although most of the instruments aboard the Voyagers are no longer functional, both missions are still returning data from the shores of the interstellar ocean and, on Nov. 5, mission controllers noticed that one of Voyager 2’s instruments, the Plasma Science Experiment (PSE), had detected a rapid change in its surrounding environment. Used to being immersed the comparatively warm and tenuous solar wind flowing past it, its plasma measurements detected a change. The spacecraft had passed into a region of space where the plasma was now denser and cooler. Three other particle experiments also detected a dramatic change; solar wind particle counts were down, but cosmic ray counts precipitously increased. Voyager 1’s PSE failed in 1980, so couldn’t measure this boundary when it entered interstellar space in 2012, so Voyager 2 is adding more detail about what we can expect happens when a spacecraft travels from the heliosphere, through the heliopause and into interstellar space. 


“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Stone in a NASA statement.

The heliosphere can be imagined as a vast magnetized bubble that is generated by the Sun. This bubble is inflated by the solar wind, a persistent stream of solar particles that ebb and flow with the Sun’s 11-year cycle. When the Sun is at its most active, the bubble expands; at its least active, it contracts. This dynamic solar sphere of influence affects the flux of high-energy cosmic rays entering the inner solar system, but the physics at this enigmatic boundary is poorly understood. With the help of the Voyagers, however, we’re getting an in-situ feel for the plasma environment at the boundary of where the Sun’s magnetism hits the interstellar medium.

To achieve this, however, we had to rely on two spacecraft that were launched before I was born, in 1977. Voyager 2 is now 11 billion miles away (Voyager 1 is further away, at nearly 14 billion miles) and it took the probe 41 years just to reach our interstellar doorstep. Neither Voyagers have “left” the solar system, not by a long shot. The gravitational boundary of the solar system is thought to lie some 100,000 AU (astronomical units, where one AU is the average distance from the Earth to the Sun), the outermost limit to the Oort Cloud — a region surrounding the solar system that contains countless billions of icy objects, some of which become the long-period comets that intermittently careen through the inner solar system. Voyager 2 is barely 120 AU from Earth, so as you can see, it has a long way to go (probably another 30,000 years) before it really leaves the solar system — despite what the BBC tells us.

So, tonight, as we ponder our existence on this tiny pale blue dot, look up and think of the two space robot pioneers that are still returning valuable data despite being in deep space for over four decades. I hope their legacy lives on well beyond the life of their radioactive generators, and that the next interstellar spacecraft (no pressure, New Horizons) lives as long, if not longer, than the Voyagers.

Read more about today’s news in my article for HowStuffWorks.com.


Meanwhile, Curiosity Has Found Something Shiny On Mars

My precious…









We Have a New Robot Heartbeat On Mars







JPL’s “lucky peanuts” at mission control obviously paid off.



Then it was time for landing. 


InSight and MarCO mission controllers celebrate the landing with NASA Administrator
Jim Bridenstine (far left) at NASA JPL 









Water Could Kill Life On Mars




In other words, death fell from the skies.











Source: Cornell University

Exocomets Seen Transiting Kepler’s Stars

ESO/L. Calçada

If you thought detecting small planets orbiting stars dozens of light-years distant was impressive, imagine trying to “see” individual comets zoom around their star. Well, astronomers have done just that after poring over 201,250 targets in the Kepler dataset.

NASA’s Kepler mission has been taking observational data since 2009, staring unblinkingly at a small area of sky in the direction of the constellation Cygnus until it transitioned into the K2 mission in 2013. In total, the space telescope has discovered over 2,500 confirmed exoplanets (and over 5,000 candidate exoplanets), transforming our understanding of the incredible menagerie of alien worlds in our galaxy. After including discoveries by other observatories, we know of over 3,500 exoplanets that are out there.

Kepler looks for very slight dips in light as exoplanets pass in front of their stars to detect alien worlds (NASA/JPL-Caltech)

Kepler detects exoplanets by watching out for periodic dips in the brightness of stars in its field of view. Should a slight dip in brightness be detected, it could mean that there’s an exoplanet orbiting in front of its host star—an event known as a “transit.” While these transits can help astronomers learn about the physical size of exoplanets and the period of their orbits, for example, there’s much more information in the transit data than initially meets the eye.

In a new study to be published in the journal Monthly Notices of the Royal Astronomical Society on Feb. 21, a team of researchers are reporting that they have found evidence for individual comets transiting in front of two stars. They detected six individual transits at the star KIC 3542116, which is located approximately 800 light-years from Earth, and one transit at KIC 11084727. Both stars of a similar type (F2V) and are quite bright.

Though other observations have revealed dusty evidence of cometary activity in other star systems before, this is the first time individual comets have been found leaving their own transit signal in Kepler data. And it turns out that their transit fingerprint is a little bit special:

One comet’s three transits around its host star, KIC 3542116. Credit: Rappaport et al. MNRAS 474, 1453, 2018.

“The transits have a distinct asymmetric shape with a steeper ingress and slower egress that can be ascribed to objects with a trailing dust tail passing over the stellar disk,” the astronomers write in their paper (arXiv preprint). “There are three deeper transits with depths of ≃ 0.1 percent that last for about a day, and three that are several times more shallow and of shorter duration.”

In other words, when compared with the transit of an exoplanet, comet transits appear wonky (or asymmetric). This is because comets possess tails of gas and dust that trail the nucleus; as the comet passes in front of its star, starlight is quickly blocked, but as it drifts by in its orbit, the dusty tail will act as a starlight dimmer, gradually allowing more starlight to be seen by Kepler. An exoplanet—or, indeed, any spherical object without a dusty tail—will create a symmetrical dip in the transit signal. Other possible causes of this unique transit signal (such as starspots and instrumental error) were systematically ruled out. (Interestingly, in a 1999 Astronomy & Astrophysics paper, this asymmetric comet transit signal was predicted by another team of researchers, giving this current work some extra certainty.)

But just because there was evidence of six comet transits at KIC 3542116, it doesn’t mean there were six comets. Some of those transits could have been caused by the same comet, so the researchers have hedged their bets, writing: “We have tentatively postulated that these are due to between 2 and 6 distinct comet-like bodies in the system.”

Using these transit data, the study also takes a stab at how big these comets are and even estimates their orbital velocities. The researchers calculate that these comets have masses that are comparable to Halley’s Comet, the famous short-period comet that orbits the sun every 74-79 years and was last visible from Earth in 1986. For the deeper transits (for KIC 3542116 and the single transit at KIC 11084727), they estimate that the comets causing those transits are travelling at speeds of between 35 to 50 kilometers per second (22 to 31 miles per second). For the shallow, narrow transits at KIC 3542116, the inferred speeds are between 75 to 90 kilometers per second (47 to 56 miles per second).

“From these speeds we can surmise that the corresponding orbital periods are ⪆ 90 days (and most probably, much longer) for the deeper transits, and ⪆ 50 days for the shorter events,” they write.

But the fact that comets were detected at two similar F2V-type stars gives the researchers pause. Is there something special about these stars that means there’s more likelihood of possessing comets? Or is it just chance? Also, the fact that these comet transits were identified by visually analyzing the Kepler datasets suggests that there are likely many more transits hiding in the archived Kepler observations.

One thing’s for sure: this is a mind-blowing discovery that underscores just how valuable exoplanet-hunting missions are for probing the environment around other stars and not just for discovering strange new worlds. I’m excited for what other discoveries are waiting in Kepler transit data and for future exoplanet-hunting missions such as NASA’s Transiting Exoplanet Survey Satellite (TESS) that is scheduled for launch this year.