30%

8% 9%

14%

4%

TOP 5 ELEMENTS ON

PLUTO

Credit: NASA

Sources: McKinnon et al. (2017). Icarus, Vol. 287. Kinnunen & Saikkonen (1983). Bulletin of the Geological Society of Finland, Vol. 55.

MgMagnesium

12

Si14

Silicon

H1

Hydrogen

Fe26

Iron

O8

Oxygen

(Bulk Composition)

Pluto is a unique, small, isolated world close to the edge of our solar system. Two-thirds of its bulk composition is rock with the remainder being water ice, but the type of rock is unknown. In 2015 NASA’s New Horizons spacecraft fl ew past Pluto and fi nally provided humanity with resolved surface compositional information. The results showed that Pluto’s surface composition is dominated by exotic volatile ices such as nitrogen, carbon monoxide, carbon dioxide and

methane as well as water ice. While there is nothing inherently special about these ices, Pluto’s unique environment (incredibly cold surface temperatures, long seasons, highly elliptical orbit, and nitrogen-carbon monoxide-hydrocarbon gas/haze-fi lled atmosphere) means these ices create surface features seen nowhere else in our solar system. These unique conditions are challenging our understanding of what these ices are capable of. Arguably the most exciting surface

compositional and geological discovery is that nitrogen ice is currently fl owing on Pluto’s surface, both as glaciers and as a large, continent-sized ice sheet. There is also evidence of ammonia-rich surface fl ows on an area (informally) known as Virgil Fossae; these surface fl ows are believed to be indicators of recent, short-lived cryovolcanism. On Pluto, water ice is so hard it provides the “bedrock” of the surface and is even capable of forming mountains. These mountains stand over 6 kilometers high, sporting methane ice caps.

Dr. Carly Howett is the Assistant Director of the Department of Space Studies at the Southwest Research Institute in Boulder, Colorado. She is mainly interested in understanding the surface properties of icy worlds, including Saturn’s icy moons, Jupiter’s Trojan asteroids, Europa, and Kuiper belt objects (including Pluto and Charon). She is the Deputy Principal Investigator of the Ralph instrument on New Horizons, an Instrument Scientist on NASA’s newly selected Lucy mission, and a Co-Investigator on two other NASA missions: Cassini and Europa Clipper. On New Horizons she helps plan observations and works on calibrating Ralph’s Multispectral Visible Imaging Camera (MVIC) and analyzing results. She assisted with the production of color images of Pluto, Charon, and Kuiper belt object 2014 MU69. While on the Cassini team she was responsible for planning the Composite Infrared Spectrometer (CIRS) observations of Saturn’s icy moons, as well as analyzing the returned data. Howett has discovered thermal anomalies dubbed “Pac-Men” on three of Saturn’s icy moons, and helped constrain active Enceladus’ heat fl ow. NASA’s Lucy and Europa Clipper missions are still in the instrument development stages. As such, Howett is heavily involved in optimizing instrument design and constructions for the upcoming missions to a jovian Trojan asteroid and Jupiter’s icy moon Europa respectively. Howett is constantly working to create equality for all in science by promoting best practices, allyship, and targeted training. She is particularly passionate about outreach to promote science to girls and other minorities. She regularly gives talks in schools, in the community, and on TV/radio. Howett is also the liaison between the Southwest Research Institute and the Denver Pop Culture Con, to provide a variety of science outreach for the Con.

Founded at the height of the Apollo program in 1968, the Lunar and Planetary Institute (LPI) is an intellectual leader in lunar and planetary science. LPI’s mission is to advance understanding of the solar system by providing exceptional science, service, and inspiration to the world. The research carried out at LPI supports NASA’s eff orts to explore the solar system.www.lpi.usra.eduwww.iypt2019.org

The year 2019 marks the 150th anniversary of Dmitri Mendeleev’s development of the Periodic System and has been proclaimed the “International Year of the Periodic Table of Chemical Elements” (IYPT2019).

Exotic ices (bluish-white areas) stand-out in this false-color image from the New Horizons spacecraft of the Sputnik Planum region of Pluto. Credit: NASA/JHUAPL/SwRI.

DR. CARLY HOWETT PLUTOSouthwest Research Institute