October 2018 Letter from the Director
October is the traditional month when most of the new class of postdocs have arrived. We celebrate their arrival and the general comradery on campus in many ways. One is the annual picnic where the decorations of Gary Bors and the pumpkin carving skills of many on campus are on clear display. A bit of good, and unexpected, news from this year’s picnic is that DTM defeated the Geophysical Laboratory in the annual tug of war competition, for the first time in this millennia, I think! DTM also led for the majority of this year’s MudCup soccer competition, though GL tied it up in the second half. The two team captains, Jesse Reimink (DTM) and Zack Geballe (GL) are to be commended for their efforts to make sure the competition was hard fought and well-played, but at the same time fair and injury free.
After 90 minutes of play, the 2018 MudCup match score ended with a 2-2 draw. DTM will keep the coveted Cup until next year, as last year the team won a hard-fought game versus the GL pistons. Photo courtesy Janice Dunlap, DTM.
On the science front, October opened with the discovery by Scott Sheppard of another object in the Kuiper Belt whose orbit provides additional evidence for being guided by the gravitational influence of a much larger, and still undiscovered, planet well outside of the orbit of Pluto. The new object, Dwarf Planet 2015 TG387, is in a highly elliptical orbit that never comes closer than about 65 AU of the Sun. Pluto orbits at around 34 AU for comparison. Scott and colleagues Chad Trujillo of Northern Arizona University and David Tholin of the University of Hawaii named the new dwarf planet “The Goblin” due to its first observation occurring near Halloween of 2015. The report of its discovery was delayed until this year so that the observers, working with colleague and former DTM postdoc Nathan Kaib, now at the University of Oklahoma, could define its orbit and examine how The Goblin could be used to refine the orbit and size of the possible large, distant, planet. The ellipticity of The Goblin’s orbit takes it out to 2,300 AU, where it would not be seen from Earth. When observed, The Goblin was “only” 80 AU from the Sun.
The orbits of the new extreme dwarf planet, 2015 TG387, and its fellow Inner Oort Cloud objects, 2012 VP113 and Sedna, as compared with the rest of the Solar System. Illustration by Roberto Molar Candanosa and Scott Sheppard, DTM.
Another science highlight on campus this month was the meeting of the COSIMA working group organized by DTM postdoc Anaïs Bardyn, a member of the COSIMA team, and involving DTM Staff Scientists Conel Alexander and Larry Nittler. COSIMA (Cometary Secondary Ion Mass Analyser) is an instrument flown on the Rosetta spacecraft to collect and analyze both the physical properties and chemical composition of solid particles emanating from the Jupiter-family comet 67P/Churyumov-Gerasimenko. The campus was rewarded with a seminar by the PI of the COSIMA instrument, Martin Hilchenbach of the Max-Planck-Institut für Sonnensystemforschung in Gottingen who described the comet’s make up as dominated by silicate and organic-rich dust that is about 3 times more abundant than ice. The majority of particles collected by COSIMA were fragile aggregates of grains a few tens of microns in size or smaller. On a related theme, Larry Nittler presented a seminar to the DTM staff on the arrival of the Hyabusa2 spacecraft at the carbonaceous asteroid Ryugu. Larry produced an image of Ryugu floating next to the Matterhorn that provides a vivid depiction of the size of this asteroid. He is one of the few Americans chosen to participate in this ambitious Japanese mission that includes rovers that are currently hopping around on the surface of Ryugu and plans to return samples to Earth. Larry will be receiving portions of the samples of Ryugu, that will be returned to Earth in 2020, for a wide variety of chemical and isotopic analyses.
Size comparison of asteroid Ryugu and Europe's famous Matterhorn. Image courtesy Larry Nittler, DTM.
Also occurring in October was the first of the new season’s Neighborhood Lectures, presented to a full house by new GL Director Mike Walter. The next Neighborhood Lecture will be presented on November 8 by DTM’s Peter Driscoll, who will be speaking on “The Geodynamo: A Unique Window into the Dynamics of Earth’s Deep Interior.” We are extremely pleased by the interest our Neighborhood Lectures have generated within the surrounding community that appears to share our enthusiasm for investigating the wonders of the natural world around us.
Earth's magnetic field, generated by the motion of liquid iron deep inside the core, reaches out into space until it is balanced by non-stop flows of Solar charged particles, also known as solar wind. Image: Roberto Molar Candanosa, DTM.
Richard Carlson, Director, DTM
Carnegie Institution for Science