On July 10, researchers using NASA’s Stratospheric Observatory for Infrared Astronomy, or SOFIA, will attempt to study the environment around a distant Kuiper Belt Object, 2014 MU69, which is the next flyby target for NASA’s New Horizons spacecraft.
When New Horizons flies by it, MU69 will be the most distant object ever explored by a spacecraft, over a billion miles farther from our sun than Pluto. This ancient Kuiper Belt object is not well understood because it is faint, small (likely 12-25-mile (20-40-kilometer across, or possibly even smaller according to recent ground-based observations), and very far away (approximately 4.1 billion miles from Earth).
To study this distant object from Earth, the New Horizons team have used data from NASA’s Hubble Space Telescope and the European Space Agency’ Gaia satellite to calculate where MU69 would cast a shadow on Earth’s surface as it passes in front of a star, an event known as an occultation. Based on this calculation — which determined the shadow would pass over open water in the Pacific — the SOFIA team will attempt to position the aircraft in the center of the shadow, pointing SOFIA’s telescope at MU69 when it passes in front of the background star. The New Horizons team will then analyze the data obtained with SOFIA to see how the light from the star changes as MU69 passes in front of it.
These observations will allow researchers to better understand the hazardous environment created by rings or other debris that may orbit MU69. This advance observation is a critical step in flyby planning before the New Horizons spacecraft arrives at MU69 on January 1, 2019.
The SOFIA observations on July 10 are another way SOFIA has been able to support the New Horizons mission, as it did in June 2015, before New Horizons made its historic flyby of Pluto.
“Back then, SOFIA was able to be in the center of Pluto’s shadow during the occultation event on June 29, 2015, providing a valuable atmospheric dataset in support of New Horizons,” said Kimberly Ennico Smith, SOFIA project scientist. “This year we’re continuing that collaboration, as SOFIA can provide information that will be critical to the New Horizons team’s plans for the MU69 flyby in 2019.”
There are differences that make SOFIA’s observations for the MU69 flyby more difficult than those done in support of the Pluto flyby. Because of its small size and large distance from Earth, the shadow cast by MU69 is about 100 times smaller than that of Pluto. This small size, relative to the positional accuracy of the aircraft, makes the planned observation very challenging for SOFIA. The small size of the shadow and the uncertainty in its position means that SOFIA might not succeed in flying through the shadow. Still, SOFIA may be able to provide important data given the plane’s vantage point from above the clouds, which removes bad weather as an observation obstacle, and given that the shadow falls in the middle of the Pacific Ocean, where it is inaccessible to smaller, ground-based telescopes.