NASA’s DART

The Dart Impactor (gold) being loaded into the faring of the launch vehicle at Vandenberg Launch Facility

Wow! Have you been following NASA’s DART mission? “DART” is one of those Ghastly-Acronyms-which-Spell-out-the-Project (GASP!) which stands for “Double Asteroid Reflection Test”. Scientists are always discouraged that their jaw-dropping projects conducted in outer space can never garner the same level of attention as inane sports and celebrity folderol–so they give missions these names with futile hopes of grasping the popular imagination. Speaking of whipping up attention, you should immediately google “DART” to see Google’s unprecedented graphic/animation (uh, and all of the information and scientific details about this project, of course).

Anyway, the project’s name aside, DART is a smashing success and something which humankind should have been working on since the dawn of the space age. Ever since we finally understood what caused those craters on the moon (which took longer than you might expect) and the Alvarez hypothesis explained what caused the Cretaceous-Paleogene mass extinction, scientists and engineers have realized that humankind needs a proper planetary defense system to protect us from meteors, bolides, comets, space shards, and whatever cosmic flotsam and jetsam has been drifting around out there waiting to wreck us the same way the poor dinosaurs got creamed.

“Grawwwwwr! Why did we spend so much on stock buybacks and so little on basic science?”

Although some previous asteroid and comet exploration missions have edged towards testing the behaviors of space objects subjected to manmade impacts and forces, the DART mission was designed specifically for the purpose of finding out about such things. Back in November of 2021 NASA launched a 610 kilogram impactor spacecraft to crash into Dimorphos (a tiny asteroid which orbits the larger asteroid Didymos). On September 26 (2022) the impactor crashed into Dimorphos as the Italian mini-satellite LICIACube looked on (as did many of our best telescopes).

Here is a NASA schematic which explains the mission (and its hypothesized outcome) far better than I could.

Of course in the grand scheme of things 610 kilograms is not very much mass–although a 610 kilogram (1340 lb) linebacker smashing into you would probably wreck your day–especially if he was running 6.6 kilometers per second (15,000 miles per hour) which was the closing velocity of the projectile and Dimorphos. Indeed, the Hubble and Webb space observatories were both keeping an eye on the collision and the results were pretty explosive.

We will await the exact numbers (scientists speculate that such an impact should release 20-30 gigajoules of energy–approximately equivalent to detonating 6 or 7 tons of TNT). Also, an EU spaceship named Hera is being dispatched to survey the results in 2026 (so more to follow). For now though, I am already breathing easier knowing that someone is finally working on this problem. Now we just need to work on the 8 billion other problems which are affecting Earth and casting a pall over humankind’s glorious future,

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An Unexpected Portrait of the Neptune System

We knew that, if the Webb telescope could make it to the L₂ Lagrange Point in one piece and deploy properly, this would be an exciting season for astronomers–but, even so, the parade of stunning new images from outer space are marvelous and demand comment. Today’s treasure is a picture of Planet Neptune and its moons as imaged by the near-infrared camera on Webb. The ice giant Neptune is made of strange cold things with a great pall of methane gas over them. Methane gas is very opaque to infrared light (which it absorbs) and so the planet looks like a frosty, haunted bowling ball with glass rings.

Ever since Pluto got demoted to “dwarf planet”, Neptune is the outermost world of our solar system. Yet the great gas giants…or even the trans-Neptunian objects like Eris and Haumea get all of the attention. No space craft has even visited Neptune since Voyage II rolled by in 1989 (the first and last time a probe entered the Neptune system).

Aside from the spectral rings, the image shows some bright sparks in a line along Neptune’s Tropic of Capricorn (which is not called that, but you get the idea). These bright spots are caused by high altitude methane clouds which are made of methane ice (which reflects infrared light better than methane gas does).

The full Webb photo has a striking focal point! Pulling back we see that Neptune’s largest and strangest moon Triton outshines the giant world it orbits. This is because Triton (which is named for the Greco-Roman deity Neptune’s merman super-son) is covered in a sheet of frozen nitrogen which reflects 70% of the sunlight which strikes it–so Triton glows like an aquamarine star in this photo. Ultimately Triton might well turn out to be be more interesting than Neptune: it is the only large moon in the solar system with a retrograde orbit (an orbit opposite of the planet’s rotation). Such an unusual orbit suggests that the moon was a little world captured by the ice giant long ago.

Triton is larger than Pluto and is one of five moons in the solar system known to be geologically active (the others being Io, Europa, Titan, and Enceladus). Voyager II spotted geysers of nitrogen gas venting from the moon. Clearly cryovolcanic activity is taking place below the strange patchwork of old ice (as explained in this confusing yet compelling map/diagram) and lakes of liquid water may exist below the moon’s crust.

I am going to keep staring at images of our strange far-off neighbor world, but I can’t wait to see what Webb photographs next!

Morning Glories!

My roommate Rennie is also a flower gardening enthusiast, but what he likes is morning glories. To make this work in Brooklyn, where space is limited, he gardens in the front yard (where there is lots of light and lots of things to climb on) and I plant my shade garden in the tree-filled back yard (admittedly, I plant a few morning glories to climb up onto the broken down structure behind the Haitian Church behind us).

Anyway, last year, Rennie ran around collecting all of the seeds from the morning glories he raised in the front yard (Grandpa Ott, chocolate cocoa, & flying saucers) and the ones I raised in the back (crimson rambler, Carnevale di Venezia, and Harlequin). He planted them all in big plastic planters and throughout the long hot summer of drought he has lugged out bucket after bucket of dehumidifier water straight from the dank basement for the thirst tropical flowers.

Unfortunately these pictures do not do them justice–the pure glowing colors are almost psychedelic–but even through the lens of my cellphone the beauty is still evident. His morning glory garden is such a triumph and it has been giving me a few seconds of unbridled joy each morning as I run past trying to get to my morning subway (mornings are not my best time–but the flowers help a bit).

I even unexpectedly captured a special visitor. Perhaps you remember this post from the depths of 2020 about rescuing a little carpenter bee which keeled over from exertion. Well, I noticed that a carpenter bee was rooting around in one of the cocoa-colored trumpets and took a close-up picture before rushing off to work. The picture came out far better than I would have expected (who knew my cheap phone had such a good macro function?). Admittedly, I only captured the carpenter bee’s behind (beehind?) but the lens picked out all of the individual grains of pollen caught up on the bee’s fur. Additionally, you can see the glistening luster of the cells which make up the flower.

September may be the second best garden month in Brooklyn: I will see if I can get some more pictures from the back yard and from the front one, before the magic fades. In the mean time, I will just assume that this bee is a direct descendant of that earlier one, just like these vines are all children of last year’s flowers. Also, thanks Rennie!