Another Juno Flyby, Another Amazing Sequence of Images of Jupiter

In July of 2016, the Juno spacecraft established orbit around Jupiter, becoming the first spacecraft since the Galileo probe to study the planet directly. Since that time, the probe has been sending back vital information about Jupiter’s atmosphere, magnetic field and weather patterns. With every passing orbit – known as perijoves, which take place every 53 days – the probe has revealed more exciting things about this gas giant.
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Pluto is What You Get When a Billion Comets Smash Together

Pluto has been the focus of a lot of attention for more than a decade now. This began shortly after the discovery of Eris in the Kuiper Belt, one of many Kuiper Belt Objects (KBOs) that led to the “Great Planetary Debate” and the 2006 IAU Resolution. Interest in Pluto also increased considerably thanks to the New Horizons mission, which conducted the first flyby of this “dwarf planet” in July of 2015.

The data this mission provided on Pluto is still proving to be a treasure trove for astronomers, allowing for new discoveries about Pluto’s surface, composition, atmosphere, and even formation. For instance, a new study produced by researchers from the Southwest Research Institute (and supported by NASA Rosetta funding) indicates that Pluto may have formed from a billion comets crashing together.

The study, titled “Primordial N2 provides a cosmochemical explanation for the existence of Sputnik Planitia, Pluto“, recently appeared in the scientific journal Icarus. The study was authored by Dr. Christopher R. Glein – a researcher with the Southwest Research Institute’s Space Science and Engineering Division – and Dr. J. Hunter Waite Jr, an SwRI program director.

The first Kuiper Belt is home to more than 100,000 asteroids and comets there over 62 miles (100 km) across. Credit: JHUAPL

The origin of Pluto is something that astronomers have puzzled over for some time. An early hypothesis was that it was an escaped moon of Neptune that had been knocked out of orbit by Neptune’s current largest moon, Triton. However, this theory was disproven after dynamical studies showed that Pluto never approaches Neptune in its orbit. With the discovery of the Kuiper Belt in 1992, the true of origin of Pluto began to become clear.

Essentially, while Pluto is the largest object in the Kuiper Belt, it is similar in orbit and composition to the icy objects that surround it. On occasion, some of these objects are kicked out of the Kuiper Belt and become long-period comets in the Inner Solar System. To determine if Pluto formed from billions of KBOs, Dr. Glein and Dr. Waite Jr. examined data from the New Horizons mission on the nitrogen-rich ice in Sputnik Planitia.

This large glacier forms the left lobe of the bright Tombaugh Regio feature on Pluto’s surface (aka. Pluto’s “Heart”). They then compared this to data obtained by the NASA/ESA Rosetta mission, which studied the comet 67P/Churyumov–Gerasimenko (67P) between 2014 and 2016. As Dr. Glein explained:

“We’ve developed what we call ‘the giant comet’ cosmochemical model of Pluto formation. We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta.”

New Horizon’s July 2015 flyby of Pluto captured this iconic image of the heart-shaped region called Tombaugh Regio. Credit: NASA/JHUAPL/SwRI

This research also comes up against a competing theory, known as the “solar model”. In this scenario, Pluto formed from the very cold ices that were part of the protoplanetary disk, and would therefore have a chemical composition that more closely matches that of the Sun. In order to determine which was more likely, scientists needed to understand not only how much nitrogen is present at Pluto now (in its atmosphere and glaciers), but how much could have leaked out into space over the course of eons.

They then needed to come up with an explanation for the current proportion of carbon monoxide to nitrogen. Ultimately, the low abundance of carbon monoxide at Pluto could only be explained by burial in surface ices or destruction from liquid water. In the end, Dr. Glein and Dr. Waite Jr.’s research suggests that Pluto’s initial chemical makeup, which was created by comets, was modified by liquid water, possibly in the form of a subsurface ocean.

“This research builds upon the fantastic successes of the New Horizons and Rosetta missions to expand our understanding of the origin and evolution of Pluto,” said Dr. Glein. “Using chemistry as a detective’s tool, we are able to trace certain features we see on Pluto today to formation processes from long ago. This leads to a new appreciation of the richness of Pluto’s ‘life story,’ which we are only starting to grasp.”

While the research certainly offers an interesting explanation for how Pluto formed, the solar model still satisfies some criteria. In the end, more research will be needed before scientists can conclude how Pluto formed. And if data from the New Horizons or Rosetta missions should prove insufficient, perhaps another to New Frontiers mission to Pluto will solve the mystery!

Further Reading: SwRI, Icarus

Thanks, Comet Pluto. Solar System Nomenclature Needs A Major Rethink

Pluto can’t seem to catch a break lately. After being reclassified in 2006 by the International Astronomical Union, it seemed that what had been the 9th planet of the Solar System was now relegated to the status of “dwarf planet” with the likes of Ceres, Eris, Haumea, and Makemake. Then came the recent announcements that the title of “Planet 9” may belong to an object ten times the mass of Earth located 700 AU from our Sun.

And now, new research has been produced that indicates that Pluto may need to be reclassified again. Using data provided by the New Horizons mission, researchers have shown that Pluto’s interaction with the Sun’s solar wind is unlike anything observed in the Solar System thus far. As a result, it would seem that the debate over how to classify Pluto, and indeed all astronomical bodies, is not yet over.

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Scientists to go Suborbital for Research

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Think again if you believe the suborbital space market is exclusively for well-heeled tourists. The Southwest Research Institute has just inked deals with Virgin Galactic and XCOR Aerospace to fly up to 17 scientific research flights. Three scientists, including Dr. Alan Stern, former head of the Science Mission Directorate at NASA and current New Horizons Principal Investigator, will become some of the first scientists to fly on a commercial spacecraft to conduct scientific research. They will fly on board Virgin’s SpaceShipTwo and XCOR’s Lynx.

“We’re another step closer to the era of routine ‘field work’ in space research,” said Dr. Dan Durda, another SwRI scientist who is scheduled to fly. “More and more researchers will soon fly with their own experiments in space, and do it regularly enough to allow the important advances that come with iterative investigations. I’m looking forward to that future and helping it become a reality.”


“We at SwRI are very strong believers in the transformational power of commercial, next-generation suborbital vehicles to advance many kinds of research,” said Stern. “We also believe that by putting scientists in space with their experiments, researchers can achieve better results at lower costs and a higher probability of success than with many old-style automated experiments.”

Alan Stern is ready to go to space. Credit: SwRI

The spacecraft will fly on short suborbital flights to altitudes greater than 107,000 meters (350,000 feet) above the internationally recognized boundary of space.

At least two SwRI researchers will fly on SpaceShipTwo, which can carry two pilots and up to six researchers, and later, there will be a dedicated six-seat research mission SS2. SpaceShipTwo’s large cabin enables researchers to work together in an “out-of-seat” micro gravity environment.

XCOR's Lynx suborbital vehicle. Credit: XCOR

SwRI researchers will also fly at least six high altitude missions aboard XCOR Corporation’s Lynx Mark I high-altitude rocket plane, which carries a pilot and a single researcher at altitudes up to 200,000 feet. Lynx I is currently in development, with test flights expected to begin in 2012.

The types of research planned includes biomedical, microgravity and astronomical imaging experiments.
Besides Stern andDurda, Dr. Cathy Olkin is also scheduled to fly on the research flights. All three scientists selected have trained for suborbital spaceflight aboard zero-G aircraft, in NASTAR centrifuges and aboard Starfighter F-104 jet fighters in the last year.

“This is a historic moment for spaceflight,” said Commercial Spaceflight Federation Executive Director John Gedmark. “A scientific research institution is spending its own money to send its scientists to space. I expect that these scientists will be the first of many to fly to space commercially. As the scientific community realizes that they can put payloads and people into space at unprecedented low costs, the floodgates will open even wider.”

Sources: SwRI, Commercial Spaceflight Federation