Category Archives: Planetary Science

Juno Red Spot Images

If you’re going to go all the way out to Jupiter, and spend months snapping pix, you really, really ought to get some pictures of the Red Spot. The Great Red Spot has been observed since 1830, but never from this close.

This week’s close flyby picked up the best pictures ever from this giant hurricane.

The visual imagery was rapidly processed to produce a pretty picture. The entire data collection will be analyzed and described soon (presumably by the end of the year conferences).

This enhanced-color image of Jupiter’s Great Red Spot was created by citizen scientist Jason Major using data from the JunoCam imager on NASA’s Juno spacecraft. The image was taken on July 10, 2017 at 07:10 p.m. PDT (10:10 p.m. EDT), as the Juno spacecraft performed its 7th close flyby of Jupiter. At the time the image was taken, the spacecraft was about 8,648 miles (13,917 kilometers) from the tops of the clouds of the planet. JunoCam’s raw images are available for the public to peruse and process into image products at: http://www.missionjuno.swri.edu/junocam More information about Juno is at: https://www.nasa.gov/juno and http://missionjuno.swri.edu Credits: NASA/JPL-Caltech/SwRI/MSSS/Jason Major

The composite image gives us the impression of this massive storm. Visually, it is clearly a really complicated “hurricane of hurricanes”.

The more detailed analysis may suggest a more refined understanding of how this storm developed and has persisted for at least 150 Earth years.

Cool.

There will be another close pass on 1 September, just before Cassini’s finial dive at Saturn. The Juno mission will end in February with a deliberate dive into the atmosphere.


  1. Agle, DC, Dwayne Brown, and Laurie Cantillo, NASA’s Juno Spacecraft Spots Jupiter’s Great Red Spot, in NASA Latest, M. Perez, Editor. 2017. https://www.nasa.gov/feature/jpl/nasa-s-juno-spacecraft-spots-jupiter-s-great-red-spot

 

Space Saturday

Dinosaurs Rising From The Ashes

We’re all fascinated with the story of the end of the Dinosaurs, which corresponds with a really big impact, and possibly other catastrophes. The death of the dinosaurs is not only a puzzle, it is the event that made room for mammals and puny humans to evolve.

But there was also a mass extinction that cleared the way for the great adaptive radiation of dinosaurs. At the end of the Triassic period, about 200M years ago, there was a massive extinction of animals. The dinosaurs rose after this catastrophe.

This month a team of British scientists published new evidence that there was a huge sequence volcanic eruptions at that time, which would have been devastating for living things. This event has been suspected from other evidence of huge lava flows, global cooling (due to volcanic material in the atmosphere), and, of course, mass extinctions.

The new study uses a new techniques which measures mercury (Hg) in the rocks. This element is highly correlated with volcanic activity, which spews Hg into the air.  The mercury falsl out and is incorporated into rock, where it persists for long periods of time–hundreds of millions of years.

Careful measurements indicate high levels of mercury in the period between the extinctions at the end of the Triassic, and the beginning of the Jurassic. In other words, a very clear suggestion that the volcanic disaster caused the extinctions, and the end of the episode was followed by the rise of the dinosaurs.

A key aspect of this work is to trace mercury deposits to many locations around the world. Furthermore, the deposits should be temporally aligned, rising and falling at the same time.   These signatures are consistent with large volcanic “pulses”.

The researchers report that the “Hg excursions are recorded in five of the six sections studied”, and that “The onset of Hg enrichment occurred synchronously across the globe, coincident with the end-Triassic extinction and associated global carbon cycle perturbation.“ (p.5)

In other words, there is clear evidence of very widespread effects of volcanism at the precise time of the mass extinctions.

As Rebecca Morelle puts it, “The onset of Hg enrichment occurred synchronously across the globe, coincident with the end-Triassic extinction and associated global carbon cycle perturbation.

And, evidently, ancestors of the dinosaurs survived this catastrophe, and “once the volcanoes had simmered down, few of their competitors were left, allowing the age of the dinosaurs to begin.”

The dinosaur age began and ended in world-wide catastophe that wiped out most living species, clearing the way for another burst of speciation.

The “age of mammals” started with the catastrophe that killed off the dinosaurs.  It is ending now with the sixth extinction, and, most likely, a spike in global temperature.


  1. Rebecca Morelle, Volcanoes ‘triggered dawn of dinosaurs’, in BBC News: Science & Environment. 2017. http://www.bbc.com/news/science-environment-40333902
  2. Lawrence M. E Percival, Micha Ruhl, Stephen P. Hesselbo, Hugh C. Jenkyns, Tamsin A. Mather, and Jessica H. Whiteside, Mercury evidence for pulsed volcanism during the end-Triassic mass extinction. Proceedings of the National Academy of Sciences, June 19, 2017 2017. http://www.pnas.org/content/early/2017/06/13/1705378114.abstract

Enceladus Fan Club News: Evidence of True Polar Wander

On the last orbit, Cassini imaged my ave-moon Enceladus from close up, and, of course,. earlier observations have sighted probably tectonic and volcanic activity, including plumes of water. (Volcanic activity is a particularly apt link to the namesake giant, who was associated with volcanos and earthquakes.)

Mosaic of Enceladus from 2005. Image Credit: NASA/JPL/Space Science Institute Image Addition Date: 2006-03-09

Radwan Tajeddine and colleagues report this spring on analysis which suggests that Enceladus has flipped 55 degrees sometime in the past [2]. This analysis is based on data collected in 2005 and later — yes, Cassini has been investigating Saturn for more than ten years now!

The new findings are based on images that show patterns of large “basins”, low areas on the icy surface. Some of the basins are located in a neat great circle, which the researchers suggest that these basins reflect patterns in convection in the liquid interior. In addition to the basins that align with contemporary poles, there are five older basins that are similar but not aligned. These do align with a similar great circle, if the pole were in a location 55 degrees from the current pole. Hence, the hypothesis that Enceladus shifted its rotational poles at some point in the past.

(Please see the paper for the details of their inferences and arguments.)

It isn’t obvious what might have caused this shift in poles. The researchers think that this may be a case of “True Polar Wander”, which can happen in slowly rotating nearly spherical objects (such as icy moons). A redistribution of mass might have led to a new axis of rotation. Considering the watery and slushy interior, this seems plausible, if difficult to verify—without landing there!

Yet one more reason to send out robots to the icy moons.

(I’m not holding my breath for the current US government to support any such project.  Trying to roll back history to the nineteenth century means no space program, though that’s the least of the harm that will cause.)


  1. Cassini Science Communications Team. Cassini Finds Saturn Moon May Have Tipped Over 2017, https://saturn.jpl.nasa.gov/news/3067/cassini-finds-saturn-moon-may-have-tipped-over/.
  2. Radwan Tajeddine, Krista M. Soderlund, Peter C. Thomas, Paul Helfenstein, Matthew M. Hedman, Joseph A. Burns, and Paul M. Schenk, True polar wander of Enceladus from topographic data. Icarus, 295:46-60, 10// 2017. http://www.sciencedirect.com/science/article/pii/S001910351630584X

 

Space Saturday

Checking in with Cassini

The Cassini spacecraft has completed 5 of its 22 final swoops, conducting a feverish rush of observations on the outbound segment.

This science program was the product of long planning and discussion, to try to jam in as much science as possible, and to take advantage of the unique opportunities of each minute of each orbit. (If you fly all the way to Saturn, you want to get as many pix as possible, no?)

One observation peered at close range at one of the rings for its entire 14 hour rotation around Saturn, to get a detailed record. Another observation observed an occultation of Sirius by Saturn’s atmosphere, data not available from any other available method.

Cassini also took close up (well, from 168,000 KM), 1KM per pixel images of my new favorite moon, Enceladus. We’re on our way, Encie!

Credit NASA/JPL-Caltech/Space Science Institute

This week also saw and episode that gives perspective to just how far out at the edge of the possible Cassini is flying. The spacecraft is tiny and far away, and communicates via the Deep Space Network. Like many people who have fussed about with computer networks, I consider the DSN as nearly miraculous. It is a tribute to its designers and operators that we take for granted that we will be able to up and down link our spacecraft, even out at Saturn and beyond. (We are not worthy!)

Nothing is perfect, and like all engineering, end-to-end issues ultimately rule. This week some of the data downlinked from Cassini was lost because of heavy rains in Australia. First of all: rain in the desert? What’s the deal with that?.   Second: we are all thankful for the blessing of rain on that parched continent.

The problem, of course, is that the signals from Saturn are weak and far away. The natural radio noise from a rainstorm is not gigantic, but is sure is close, and (literally) drowned out the downlink.

The downside of one-of-a-kind observations is that and error or loss is unrecoverable. That data will never be seen.

As I said, rare problems serve to highlight just how robust the DSN has been for decades now.

Cassini continues to roll along, working like mad right up to the end in September.


  1. Cassini Science Communications Team. Cassini Significant Events 5/17/17 – 5/23/17. 2017. https://saturn.jpl.nasa.gov/news/3066/cassini-significant-events-51717-52317/

 

Space Saturday

Cassini’s Final Swoops

After more than a decade, the Cassini Spacecraft is nearing the end of its mission. The final phase will be a fiery plunge into the atmosphere of Jupiter, beaming back as much data as it can before burning up and.or being crushed by the gas giant. The final dive is intended to assure that no trace of Earth accidentally reaches one of the moons, which may have their own life.

This month sees the first of 22 rinplane crossing orbits, deep dives between the rings and the atmosphere. I mean, you go all the way to Jupiter, you want to get as many cool pix as possible, right?

NASA released a neat image, with sentimental tag “Cassini’s Last View of Earth”, a reminder that the spacecraft is far from home and never returning.

Cassini’s Last View of Earth Credit: NASA/JPL-Caltech/Space Science Institute

The image is especially striking because the glimpse of Earth through the rings is so tiny. Cassini is a long, long way from home.

There will be 22 orbits, each about six days, ending in the final plunge, This week saw the “First Ringplane Crossing” and the “Grand Finale Dive #2” (which would be great names for bands!).

Cassini will perform 22 orbits of Saturn during the Grand Finale.

We wonk get data back for a while, it takes time to beam stuff home.

And think about the skill and precision required to hit that tiny little dot with the downlink!

If all goes as planned there will be 15 more Ringplane crossings, lower and lower, until the last 5 swoop through the atmosphere. This will take all summer, with last call will be September 15.


NASA is a neverending cornucopea of nerdy names for bands.

In addition to “First Ringplane Crossing” and  “Grand Finale Dive #2”, this project also brings:

  • “The Grand Finale Toolkit”
  • “Last View of Earth”
  • “Final – and Fateful – Titan Flyby”

 

Space Saturday

Robots on Enceladus!

In the last two decades, we have established that this solar system is awash in water, albeit mostly dirty ice. That’s good news for our 98%-water species, at least in the very long term. Whatever else, we shouldn’t die out of thirst.

Even more interesting are the “ocean worlds“, icy moons of Neptune and Saturn (and, who knows, outer planets such as Pluto and Uranus), which probably have a liquid ocean underneath a thick crust of ice.

As I have noted earlier, ESA and NASA are gearing up to explore these worlds, because we just have to.  A prime target is the large moon Europa, which has a fissured icy crust and, most likely, a watery ocean below.

This week Waite, J. Hunter and colleagues report on yet another moon, Enceladus, which also has an icy crust ovre a liquid ocean. Enceladus also has active volcanoes !spewing water vapor. Whoa!

Enceladus is also notable because the Cassini spacecraft actually visited and swooped through one of the volcanic plumes to take a sample.

As Waite et al report, this sample contains water with traces of several other species, including H2. (See [2] for the details of this non-trivial measurement, a billion KM from home.) The researchers are particularly interest in H2, because they theorize that it is generated by “ongoing hydrothermal reactions of rock containing reduced minerals and organic materials.” They also calculate that this indicates “thermodynamic disequilibrium that favors the formation of methane from CO2 in Enceladus’ ocean “ (p. 155)

The thermodynamics and Hydrogen are both highly favorable for microbes, so these findings suggest that the ocean is “habitable”. This makes Enceladus a tempting target for a landing mission.

“We’re pretty darn sure that the internal ocean of Enceladus is habitable and we need to go back and investigate it further,” said Cassini scientist Dr Hunter Waite from the Southwest Research Institute in San Antonio, Texas.”  (quoted in [1])

So now we have at least two high priority “ocean worlds” that we should must visit.

The good news is that the gear being developed will work for missions to either or both Enceladus or Europa.

It is difficult to be optimistic about the prospects for government funding for such missions (unless someone’s family can make a bundle off the “deal”).

But, why aren’t the Silicon Valley hobbyists all over this stuff? This is way more interesting than sending rich tourists into low Earth orbit, and probably cheaper, too.

So let’s all raise a glass to my new favorite, “Robots on Enceladus!”

Suck on that, Europa.


  1. Jonathan Amos, Saturn moon ‘able to support life’. BBC News – Science & Environment.April 13 2017, http://www.bbc.co.uk/news/science-environment-39592059
  2. J. Hunter, Waite, Christopher R. Glein, Rebecca S. Perryman, Ben D. Teolis, Brian A. Magee, Greg Miller, Jacob Grimes, Mark E. Perry, Kelly E. Miller, Alexis Bouquet, Jonathan I. Lunine, Tim Brockwell, and Scott J. Bolton, Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes. Science, 356 (6334):155-159, 2017. http://science.sciencemag.org/content/356/6334/155

 

Space Saturday

Lunar Regolith Student Project

A team of local students have been selected as finalists to send a prototype to the moon on the Google X Prize moonshot. Specifically, The Regolith Revolution project is preparing to be on the Team Indus lander.

The challenge posed was

Imagine, design, and build a project to catalyze the evolution of humankind as a sustainable multi-planetary species.

OK, that’s a preposterously broad challenge, not least because we have no way to actually travel between planets. But that shouldn’t stop bright kids from trying to build something interesting.

Their answer is “Create a prototype that test different fertilizer abilities to turn lunar regolith fertile.”  I.e., explore how to grow Earth plants on the moon.

The Apollo program returned samples of rocks and soil (regolith) from the moon, which is the only samples ever returned from another planet. Earth-bound studies of the soil show that regolith is (not surprisingly) sterile, but is a perfectly good growing medium, once you add water, air, and fertilizer. (There is plenty of sunlight available, at least at the right place and time.)

Combining what they are learning in Agricultural Engineering and Mechanical Engineering, with contributions from others and the first rate facilities of the University of Illinois, Urbana Champaign, they have built a robot lab to conduct experiments on the surface of the moon.

The team describes the product as:

The device is about the size of a beverage can and has an Archimedes screw that drills into the ground, lifts lunar soil (also called regolith) into the shell, and drops it into rotating cups. When the screw retracts, the hole closes and the device pressurizes and heats up. Tubes deposit seeds, water and fertilizer into the cups.

This is only a first step toward “the evolution of humankind as a sustainable multi-planetary species” (and it is certainly not a “galactic greenhouse” as the University press release gushed), but growing plants is a very important thing to understand, no?

I’m not a big fan of the current race to colonize the solar system, mostly because there is so much hype per unit of talk. Frankly, I don’t know if it will ever make sense to try to live on the Moon or Mars, except as visitors. (Orbital habitats, maybe.)

But that doesn’t mean we shouldn’t learn more about the moon.

It is also great to see this attempt to do in situ experiments. Regardless of the heroic achievements of my generation, studies of regolith on Earth are no substitute for studies on the moon.

How will this process actually work out in microgravity, lunar sunlight, and the real possibility of dust getting in the moving parts and electronics?  How will the plants fare in a really, really sterile environment–no symbiotic microbes, fungus, insects, or anything?  We shall have to see.

I say, “bravo!”, let’s shoot it off to the moon.

Nice work, all!


  1. Leanne Lucas. Engineering students design galactic greenhouse. 2017, http://engineering.illinois.edu/news/article/21407.
  2. Regolith Revolution. Regolith Revolution. 2017, https://regolithrevolution.com/.
  3. Team Indus, Team Indus, 2017.