Posted November 9, 2015

New Horizons heading to next target

The other day New Horizons, the spacecraft that recently flew by Pluto, changed its course towards 2014 MU69, a recently discovered member of the mysterious class of Kuiper Belt Objects. In January 2019 New Horizons is expected to arrive there and send pictures. We will get to know another member of the Solar System. Wired has a very interesting description of the way New Horizons was steered in the right direction this week.

The Kuiper Belt is a field of objects that orbit the Sun outside of the orbit of Pluto. Comets probably originate there. Kuiper Belt Objects (KBOs) are thought to be remnants of the formation of the Solar System. That's why astronomers hope to find clues to the formation of said Solar System by studying comets and KBOs.

The difference between comets and KBOs is that comets have been studied, both by telescopes and by space missions like Giotto and Rosetta. They can be studie because they enter the inner Solar System en can be reached optically by telescopes and physically by space probes. Nobody ever saw a KBO except as a faint dot in a telescope picture.

Thanks to modern very sensitive telecsopes like Hubble many KBOs are now known. In fact, this has caused the downgrading of Pluto from planet to dwarf planet. Many similar sized objects are now known to exist and Pluto is no longer the outermost planet-like satellite of the Sun.

Back in August NASA selected 2014 MU69 al New Horizons' next target. It was favored over a somewhat larger rival because the necessary trajectory corrections required less fuel, leaving open the possibility to deal with unforeseen circumstances or even visit yet another KBO afterwards.

In the past two weeks several rocket burns changed New Horizons' course in the direction of where 2014 MU69 is going to be three years from now. After each burn the course was analyzed using radio telemetry for the position and direction of the spacecraft, and data from the Hubble space telescope to assess the position of 2014 MU69. Things are looking good now and no further corrections are foreseen until the second half of 2016.

In january 2019 this means being 3.5 million miles away from where it otherwise would have been. Sounds like a sharp turn, right? Nope. Since the craft will  heave flown almost 900 million miles by then, the change in direction is only about a quarter of a degree. To give you another idea of the tremendous distances and velocities involved: after the Pluto flyby New Horizons has traveled more than the distance between the Earth and the Sun. Another 15 of those 'Astronomical Units' (AUs) separate it from 2014 MU69.

Since 2014 MU69 is very small (probably just tens of miles across) NASA will probably try to fly very close by. At a distance of 4000 miles the object will be only 1000 pixels across on the on-board camera. With a margin of 300,000 miles at this point, there will be plenty more high precision engineering to do.

About Herbert Blankesteijn

Herbert Blankesteijn is a technology journalist from the Netherlands who has written for many prominent Dutch newspapers. He presented and directed television and radio programmes and has 10 books to his name. Herbert is interested in nascent fields such as 3D printing, drones, robotics and the private space business.