Tag Archives: NASA

The seven rocky worlds of TRAPPIST-1

NASA had a big announcement today: the dwarf star TRAPPIST-1 has at least seven terrestrial planets, and at least three of them are in the star’s “goldilocks zone”, where liquid water could exist on the surface (assuming sufficient atmospheric pressure).

TRAPPIST-1 got its name from a Belgian telescope called the Transiting Planets and Planetesimals Small Telescope, situated at La Silla Observatory in Chile’s Atacama Desert.  TRAPPIST found that the star (catalogue number 2MASS J23062928-0502285) had at least three exoplanets orbiting it by observing the star’s lightcurve change as the planets transited.

Subsequently, NASA’s Spitzer Space Telescope was called in to confirm the discovery, in a marathon 500-hour focused study of the TRAPPIST-1 system.  And it did!  Today, NASA announced that not only are the three worlds real, there are at least four more.  And at least three but possibly all of them are in the habitable zone.  This is the largest collection of terrestrial worlds ever found.  Since they orbit quite near their dim parent, astronomers were able to calculate their densities, and they’re pretty close in size to Earth — some are actually smaller.

The Hubble Space Telescope is now being called in to study the planets in more detail, and hopefully to determine whether or not any of them has a substantial atmosphere, preferably one with an unusual concentration of hydrogen, which would imply water vapor.  So far, it hasn’t found evidence of an atmosphere (and has largely ruled out the kind of atmosphere we’re all hoping for on TRAPPIST-1b and TRAPPIST-1c), but they’re still looking, and the search is expected to continue into the James Webb Space Telescope.  The hobbled Kepler Space Telescope (now “K2”) has also been studying this system.

Here’s an artist’s concept, to show you the relative sizes (note that color is completely imaginary at this point):


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The Rockets of LC-39A


Yesterday, LC-39A moved into a new chapter by launching a Falcon 9, but it’s just the latest of many chapters.  Originally constructed in the 1960s for the giant Saturn V rocket, and consequently one of the biggest and toughest pads in the world, it has hosted four different rockets in its history (five if you count a different configuration of Saturn V).  I thought I’d share clips of each of them taking off.  😉

Here’s the first launch from LC-39A, of the uncrewed Apollo 4 test flight:

The pad would host many more Apollo launches, including Apollo 11.  After the Apollo mission was over, NASA got funding to expend the surplus hardware mounting the Skylab program.  The last launch of a Saturn V came from LC-39A and placed the Skylab space station into orbit, easily the most massive single payload of any mission in history:

Following this, the crewed missions to Skylab were launched using the much smaller Saturn 1B (itself an impressive rocket, but most things look small next to Saturn V).  However, the pad originally used for Saturn 1B Apollo flights out of Cape Canaveral Air Station was no longer configured for it, so NASA modified one of the Mobile Launchers to basically adapt Saturn 1B to a Saturn V launch tower — by adding a structure nicknamed “the milkstool”.  Here’s the final Apollo mission, for the Apollo-Soyuz Test Project in 1975.

After that, LC-39A would not see another flight for nearly six years.  During that time, it received substantial modifications for the Space Shuttle program.  The Mobile Launchers were stripped of their towers, in favor of a Fixed Service Structure that would remain permanently at the pad.  The Apollo-era Mobile Service Structure, which normally sat parked about a mile from the pad, was scrapped as well, in favor of a Rotating Service Structure that would sit attached to the FSS at the pad.  And in April of 1981, the Space Shuttle Columbia baptized the modified pad with her own fire (notice the white External Tank, and Columbia’s distinctive black chines):

And then, thirty years later, the Shuttle era came to an end with the final flight of Atlantis, also from LC-39A:

After that mission, LC-39A was mothballed.  39B was earmarked for the Space Launch System, the next monster rocket, and has been converted back to a “clean pad” configuration, a la Apollo.  But 39A had no immediate mission and was offered up to civilian use.  It took a while, but eventually SpaceX made a case for adapting it to the massive Falcon Heavy rocket.  SpaceX has left much of the original Shuttle-era hardware present, including the FSS and RSS (although both were long since stripped of salvageable and historic gear by NASA); I’m not sure whether they plan to keep them all there.  Their eventual crew-access arm could be added to the FSS, but the RSS has little value for them.  But in the meantime, it is good to see the pad back in use, and slightly quicker this time.  😉

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GOES-16 catches the Moon

I have a particular fondness for pictures of the Earth and Moon together.  NOAA’s latest weather satellite, the ground-breaking GOES-16, produced this particularly stunning example.  It’s currently in its commissioning phase, so it isn’t yet contributing to weather forecasting.  But it will, and when it does, it will be spectacular.  This image was taken from geosynchronous orbit — 22,000 miles away.  Earth and Moon are natural color, and this is not a composite — this is the image it actually took.  It can be surprising to see the Moon look so dark; we’re used to seeing it so bright in our night sky.  But it’s really because the Earth is so much brighter.  The Moon is of course not a usual target for a GOES satellite; but it still will take pictures of the Moon every now and again for calibration purposes, since unlike the Earth, the Moon looks very much the same from one orbit to the next.  For now, though, this image exists mostly to be beautiful.  Enjoy it!


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Daphnis, the ring-sculptor

Strictly speaking, Daphnis is one of many ring-sculptors — the shepherd moons that maintain some of the notable visual features of the rings of Saturn.  In the case of Daphnis, that’s the Keeler Gap, a narrow gap carved out the A ring by the gentle gravitational tug of war between Saturn and the tiny moon.

Daphnis was actually discovered by the Cassini probe in 2005, but its existence was suspected long before, when the Keeler Gap was itself discovered in images taken by the twin Voyager probes.  Voyager had already discovered the moons Prometheus and Pandora, which the Voyager team dubbed “shepherd moons” for the way their push and tug confined a group of particles to the very narrow F-ring.  So it was surmised that the other gaps would turn out to have moons creating them as well. Mimas seems to be responsible, at least in part, for both the Cassini Division and the Huygens Gap, and of course Prometheus and Pandora constrain the F ring.  Pan, discovered in 1990 from old Voyager data, is likely responsible for the Encke Gap.  And Daphnis is the sculptor of the Keeler Gap.

Or, at least, the main sculptor.  Saturn’s rings are very complex, and serve as a fascinating natural laboratory for studying gravitational interactions, and particularly the sort hypothesized to have created the solar system as we know it.  And Daphnis, like other shepherd moons, does not orbit perfectly neatly.  Its orbit is slightly inclined relative to the ringplane, and slightly elliptical as well.  Thus, it doesn’t produce a nice tidy circle, but carves out waves as it passes — waves both ahead and behind, and, as this recent Cassini image shows, sometimes it pulls off delicate tendrils of ring particles (look verrrrry closely, or just click to enlarge – you’ll see a thin wisp of material echoing the shape of the nearby wave in the ring):

That’s the closest image ever taken of Daphnis, a tiny moon roughly the same size as Mount Everest.  It appears to have striations running down its length, probably the result of accumulated ring particles — sometimes, even a tiny moon like this will manage to capture something and pull it down.  But if you want a more dramatic image of this effect, you will have to look at Daphnis near Saturn’s equinox, when the shadows are at their longest.  Then you can see what is hidden in this image: the waves aren’t just flat features.  They stand surprisingly tall.

By studying this process, scientists hope to better understand planetary formation.  Indeed, they’ve even found a few spots in Saturn’s rings where it appears that moonlets may be in the process of forming, clumping together at random until eventually one clump reaches a critical mass and begins to dominate the particles around it, gradually growing until it exhausts its immediate surroundings, carving out another gap.  Daphis itself shows signs that it may be accumulating material.  Saturn’s rings are an astonishingly and fascinatingly dynamic place.

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NASA announces two new deep space missions: Psyche and Lucy!

So here’s something else to look forward to: today NASA announced two missions to asteroids.  Psyche will visit the asteroid 16 Psyche, a gigantic nickel-iron asteroid so big that astronomers have speculated it could be the core of a destroyed planet.  Lucy, meanwhile, will visit half a dozen Trojans — asteroids co-orbital with Jupiter, swept up into Jupiter’s enormous Lagrange points.  Four of Lucy’s targets are around the Sun-Jupiter L4 point, and the other two are at the L5 point.  (“Points” is a little misleading here, by the way.  There’s actually a vast zone in which lagrangian companions might be found.)

Both are relatively fast and inexpensive Discovery class missions.  The Discovery class missions have an impressive legacy despite their austere nature — NEAR, Mars Pathfinder/Sojourner, Lunar Prospector, Stardust/NeXT, Genesis (which had an unfortunate failure of the sample return capsule), CONTOUR (lost due to an engine failure), MESSENGER, Deep Impact/EPOXI, Dawn, Kepler, GRAIL, and InSight.  These missions also share heritage with New Horizons, as they are slated to use newer versions of some of the instruments first flown on that mission.

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Pegasus flies again, placing new hurricane-spotting eyes into orbit

Pegasus, the world’s first commercially-developed rocket dating back to 1990, does not fly very often, but when it does it’s rather special — not only is it a commercial launch vehicle, but it’s the world’s only air-launched orbital rocket.  On a typical flight, it is carried to the launch site on the belly of a customized L-1011 Lockheed Tristar — itself something of a rarity, as Lockheed’s entry into the widebody market was shortlived, and most have now retired — this is one of only eight Tristars still in operation.  This one is named Stargazer, and this is its first launch while wearing the new Orbital ATK livery.

The payloads for this flight is a set of eight microsatellites called CYGNSS (no relation to the Cygnus spacecraft, which of course Orbital ATK also builds and operates), which will be operated by NASA to study hurricane formation, gathering data currently only available by daring flights into the eyes of hurricanes by P-3 Orion crews.

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Curiosity’s drill is down

The Mars Science Laboratory “Curiosity” is an amazing vehicle in an exceptionally hostile environment, and it seems it is having some issues with its drill.  The drill itself is working fine, but the motor that extends the drill bit forward to touch the rock face is not cooperating.  As a consequence, Curiosity is on non-drilling duties while the JPL team analyzes the problem and decides what to try next.  Fortunately, it has a wealth of other instrumentation, so Curiosity has been far from idle.  Here’s one of the pictures it took while on its “drilling hiatus”:

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