Hot on the heals of the 50th anniversary of the Apollo 8 trip to the Moon we have the real time fly past of Ultima Thule on New Years Day, only this time the distance is over 6.5 billion kilometres from Earth, rather than the 300,000 kilometres to the Moon. To be fair on the crew of Apollo 8, there’s no one on New Horizons so they, like their colleagues who also visited the Moon, still have the record for going the farthest from Earth. New Horizons has the record for going the farthest and sending back pictures, obviously the two Voyager probes have the record for distance. Hopefully the US government shutdown won’t effect our viewing of this historic event on New Years Day.
New Horizons was launched on 19 January way back in 2006 to go and have a look at Pluto, which it did in 2015. On the way to Pluto the spacecraft also did a flypast of a small asteroid and Jupiter. The flypast of Jupiter gave the little spacecraft the gravity assisted boost to fling it out to Pluto. Whilst sailing past Jupiter it snapped some very nice pictures of Jupiter and a few of its Moons.
There are seven instruments on board the New Horizons spacecraft to conduct a range of measurements and collect images. The first of these is the Long Range Reconnaissance Imager (LORRI) which is used, as the name would suggest, to take picture from a distance. To do this the instrument is basically a CCD (Charged Coupled Device) attached to a telescope. The telescope is an 8.2″ or 208mm Ritchey-Chretien and the CCD is 1024 X 1024 pixels. There are two other cameras on the spacecraft and we are well used to the fantastic results they produce from the stunning images of Pluto and Charon that were sent back in 2015. The other sensors on board are used to measure solar particles, look at UV light and count dust particles. All of these instrument will help scientists understand Ultima Thule in 5 days time.
So what do we know about Ultima Thule at the moment? Not a lot, other than it might be two bodies stuck together and is probably brown/reddish in colour. The object is about 6.5 billion kilometres from the Sun so only gets a tiny amount of sunlight, about 0.05% of what we get on Earth. The object is about 30km in diameter. During July last year Ultima Thule passed in front of a star, which allowed scientists to take a bunch of measurements and determine it’s shape and possible composition. This is when they worked out it has an unusual shape that could either be two spherical objects orbiting each other or the two of them stuck together. New Horizons will pass within about 3500km of the object before heading off deeper into the Kuiper Belt to look for more interesting objects. Ultima Thule will be able to tell us a lot about the conditions in the outer Solar System 4.6 billion years ago when the object formed.