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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!
Happy (belated) Fourth of July! While everyone was out barbecuing and amusing themselves with colorful novelty explosions, there was big news in space exploration: NASA’s Juno probe, which launched from Earth five years ago, has finally reached the gas giant planet and entered orbit. The robot spacecraft, which is about the size of a basketball court, is now dancing nimbly amongst the system of moons and rings and radiation belts around the giant world.
The probe is a remarkable spacecraft. It traveled 2.7 billion kilometers (1.7 billion miles) to reach the exact orbit which NASA planned for it. The secret behind its astonishing precision (even when traveling at 165,000 mph) is the autonomy of its sophisticated navigational computer. Mission controllers do not have to radio the probe from half-way across the solar system (which would take minutes—or longer. Instead the probe navigates itself. The ship computer is shielded beneath a titanium vault to keep radiation from frying its clever electronic brain.
Oh man!
Among the planets, Jupiter is a sort of greedy eldest child. Scientists who study planetary formation believe that the gas giant formed first of all the planets and it took the lion’s share of available matter left over from the formation of the sun. Jupiter is more than twice as massive as all the other planets in our solar system put together: indeed, it is three hundred and eighteen times more massive than Earth. Yet we know shockingly little about this bruiser. Very basic questions about Jupiter remain unanswered. For example we still do not know whether the planet has a rocky core beneath its vast colorful atmosphere.
As we learn more about exoplanets which orbit other stars, questions about the formation of solar systems have become more numerous. Astronomers have been particularly perplexed by the number of “hot Jupiters,” giant gas planets which are extremely close to their stars. Was Jupiter such a world at some point before moving to its current location, or is it a huge freak? We simply do not know. Scientists would also like to know more about the unimaginably vast cloudscapes of Jupiter. What dynamics move these huge bands of pressurized gas?
As Jupiter formed, it was bombarded by strange radiation. The depths of Jupiter’s storms must still feature giant lightning strikes. This sort of treatment can cause hydrocarbons and ammonia to form amino acids. Maybe life has a Jovian origin. Maybe Jupiter still has life floating around like aerial zooplankton. Again, we just don’t know much about the giant world…
Did anybody see that amazing episode of “Cosmos”?
However, now that Juno has arrived we can start to answer some of these questions. The probe will go through various start-up and test sequences until Oct. 19 when it moves to a 14-day orbit of the planet and really starts scrutinizing our giant neighbor.
Oh, one more thing—NASA has been getting better at PR to make space more accessible and “fun” for us laypeople following at home (as witnessed by the July 4th arrival). Juno also has a crew of three Lego astronauts: Galileo, Jupiter, and Juno herself. This leads me to write about Juno herself, for she is a terrifying figure among the gods. More about her tomorrow!
When I was a child, my favorite tv show was Carl Sagan’s Cosmos. Although the good doctor’s naïveté about cold war politics sometimes dismayed my realpolitik-minded parents, the amazing breadth of his show’s exploration of the natural world–and the wider universe beyond–was a wonder to me. For the first time I was introduced to quasars, pulsars, and stellar aging. From Sagan’s delightfully filmed documentary, I learned about Kepler, the Kreb’s cycle, DNA pair sequencing, and the great library of Alexandria. The eclectic scope of Cosmos was a direct inspiration for this blog (although I can hardly claim to be such a polymath). Hopefully the new Cosmos–with a new science hero, Neil deGrasse Tyson–will inspire today’s generation of children to look beyond sports and the internet up to the soaring science of the firmament!
Jovian Life Envisioned by Adolf Schaller for COSMOS, Carl Sagan (1980)
My very favorite segment of Cosmos however, did not involve real science at all, but rather airy speculation about extraterrestrial life on a gas giant planet. Carl Sagan, his physicist colleague, E. E. Saltpeter, and the space artist, Adolf Schaller, worked together to imagine a floating ecosystem which might exist on a planet such as Jupiter. In the tempestuous atmosphere of such a world, ammonia, hydrogen, methane, and water are violently stirred together to form organic molecules. Small drifting organisms might feed on these compounds and reproduce as lighter spores before air currents bear them down to their doom (in a cycle reminiscent of phytoplankton). Giant floating life-forms like living hot-air balloons would stay in the habitable zone of the atmosphere by photosynthesis or by grazing on the microscopic “plankton”. These beings could be kilometers in diameter and would congregate in vast aerial schools. Sagan and Saltpeter even envisioned jet-propulsion super predators which would blast through the alien skies feeding on the huge clouds of “floaters”.
It is a tremendously compelling vision! Now, whenever NASA or ESA releases a new list of exoplanets, I pause to wonder whether such alien creatures are actually found floating on the super-Jupiters and strange giant worlds which orbit far-off stars. However today I would like to present an even more fantastic vision—and one which humankind could actually create! By combining Sagan’s imaginary vision with contemporary aerospace and biotech research, it is possible to visualize my own fantasy of human colonization of Venus…or even upon other worlds with complex atmospheres.
Ornithopter based on Jellyfish (Dr. Ristroph and Dr. Childress)
Just this year, two aeronautical engineers, Dr. Ristroph and Dr. Childress, crafted an ornithopter based on the swimming motion of a jellyfish. The tiny mechanism relies on four teardrop-shaped wings oriented around a dome-like apex to achieve stable, directed flight. At the same time a new array of futuristic blimps, zeppelins and dirigibles are being brought to market to transform the skies of earth. Most importantly Craig Ventner, the bioengineer-entrepreneur, is out there sampling the esoteric genetics of the deep ocean and forging ahead with synthetic genomics (which is to say he is building new living things from scratch). In our lifetime someone will figure out how to meld Ventner’s synthetic organisms with the advanced engineering and technology which are the hallmark of our age. The possibilities then grow exponentially out of this world.
“Space Zeppelin” by Rugose.
Imagine if the floating ecosphere invented by Sagan and Saltpeter were instead a floating society-economy based on advanced engineering and bioengineering. There would be levitating cities which are also bioengineered life-forms (like the vast balloon beings of Sagan’s invention). Between these cloud cities would fly flocks of tiny ornithopters that would gather resources for further farming/engineering.
Jet propelled aircrafts and super habitats would zip between the living arcologies. Armored crawlers would inch through the deeper layers of atmosphere or creep along the molten pressurized ground. Eventually there might be flying bio-colonies which self arrange out of many highly specialized flying zooids—like the siphonophores which are so prevalent in our oceans! These collective entities would act as sky factories to build an ever more symbiotic and efficient synthetic ecosystem. Humankind, living things, and technology would no longer be at odds but would grow together to form the ideal world of tomorrow. Life, beautiful and united would expand to new planets and develop into a stronger, brighter presence in the cosmos.
Siphonophorae (Ernst Haeckel, 1904, plate 7 of “Kunstformen der Natur”)
The surface area of Earth is about 510 million square kilometers. That number adds some perspective to the giant storm which has been raging on Saturn since December and now covers approximately 4 billion square kilometers of the gas giant planet.
The Storm Raging on Saturn (photo from the Cassini probe, NASA)
Saturn’s atmosphere is usually calm and tranquil–although powerful storms have been observed by telescope in the past. Now however Saturn is being closely observed by NASA’s Cassini space probe which is in orbit around the planet and we have some precise details. At the storm’s height, Cassini detected over 10 lightning strikes per second. Additionally, these lightning bursts can emit 10,000 times the amount of electrical energy as a typical lightning burst on Earth. Saturnian meteorologists (or whatever weather scientists for the great ringed planet are called) speculate that this super lightning is so powerful because of the juxtaposition of layers of water ice with layers of crystallized ammonia.
A Detailed False Color Picture of the Storm (NASA)
Saturn’s weather is known to fluctuate with the change of the season on the frigid planet and the huge rings are presumed to affect the weather in unknown and unpredictable ways. The current giant storm is taking place in the northern hemisphere of Saturn, which is entering spring.
Although Saturn’s storms are not as well-known as the Great Red Spot on Jupiter, the planet’s north pole does feature a hexagonal storm which has persisted for at least 25 years. Named for Jupiter/Zeus’ father (who was known as Cronus to the Greeks), the planet Saturn is the second largest in the solar system with a surface area of 4.27 x 1010 square km. The planet is orbited not only by its famous rings but also by at least 62 known moons including Titan, the only known satellite with a dense atmosphere, and Mimas, which features the largest known impact crater.
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