KBO selected for New Horizons’ second target
Only a month and a half after New Horizons’ historic Pluto system flyby, the mission team has selected a potential target for the spacecraft’s second visit – the tiny Kuiper Belt Object (KBO) 2014 MU69, also known as “PT 1” (Potential Target 1). Orbiting almost a billion miles beyond Pluto, 2014 MU69 is estimated to have a diameter slightly under 30 miles (45 km).
PT 1 was one of five potential KBOs discovered via the Hubble Space Telescope in 2014 after a search started three years earlier had failed to find any targets the spacecraft could reach with its limited fuel supply.
New Horizons was designed to explore both the Pluto system and small KBOs beyond it, according to the 2003 National Academy of Sciences Planetary Decadal Survey – titled “New Frontiers in the Solar System”.
The goal was to study the diversity of objects in the Kuiper Belt, which are made up of primordial materials from the early days of the Solar System, in a region that has never been explored.
Because they are so distant from the Sun, KBOs – such as 2014 MU69 – are heated only minimally, unlike asteroids. That is why they are thought to contain frozen samples of material that made up the outer Solar System during the time of its formation 4.6 billion years ago.
The New Horizons mission team searched for potential targets starting in 2011, using the world’s most powerful ground-based telescopes, but the KBOs they had discovered were too far for the spacecraft to reach.
Three years later, with the threat of time running out on finding an appropriate target, mission scientists were given time on the Hubble Space Telescope and quickly found five potential targets, which were subsequently reduced to two, both within the spacecraft’s flight path.
PT 1 was ultimately selected because the trip there will require less fuel than would the visit to the alternate object.
To assure enough fuel for the KBO flyby and to minimize risk, the target KBO had to be selected early.
In late October and early November of this year, the New Horizons team will conduct four separate maneuvers aiming the spacecraft at its second target, with an encounter date of January 1, 2019.
Following NASA protocol for extended missions, the New Horizons team will have to write a formal proposal to the agency, to be submitted in 2016. That proposal will then be evaluated by a group of experts chosen by NASA, who will decide whether it should be approved and funded.
John Grunsfeld, head of NASA’s Science Mission Directorate and an astronaut himself, said that the KBO flyby is expected to be less expensive than the Pluto encounter, which was New Horizons’ primary mission. All the same, the secondary mission is expected to produce “new and exciting science”.
The spacecraft will fly within approximately 7,800 miles (12,500 km) above 2014 MU69, the same distance within which it flew by Pluto.
Team member John Spencer acknowledged the desire for a closer flyby, but that depends on how quickly the spacecraft’s cameras can be rotated.
The chosen KBO is one of the “cold, classical” KBOs, a different class of object from Pluto. However, it is presumed to have a composition similar to the building blocks of Pluto and other small Kuiper Belt planets.
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” said principal investigator Alan Stern. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”
Designed to fly to at least one additional object beyond Pluto, the New Horizons spacecraft is equipped with additional hydrazine fuel for just this purpose. Its science instruments were created to operate in light levels even lower than those expected at 2014 MU69. The spacecraft’s power system will function for a long time, and its communications system was constructed to operate far beyond Pluto.
While PT 1 is ten times larger and 1,000 times more massive than the average comet, it is, at most, one percent the size and 1/10,000th the mass of Pluto.
“There’s so much that we can learn from close-up spacecraft observations that we’ll never learn from Earth, as the Pluto flyby demonstrated so spectacularly,” Spencer said. “The detailed images and other data that New Horizons could obtain from a KBO flyby will revolutionize our understanding of the Kuiper Belt and KBOs.”
Video Courtesy of NASA
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.