Warming up for a possible extended mission as it speeds through deep space, NASA’s New Horizons spacecraft has now twice observed 1994 JR1, a 145-kilometre (90-mile) wide Kuiper Belt object (KBO) orbiting more than 3 billion miles from the Sun. Science team members have used these observations to reveal new facts about this distant remnant of the early Solar System.
Taken with the spacecraft’s Long Range Reconnaissance Imager (LORRI) on 7-8 April from a distance of about 111 million kilometres (69 million miles), the images shatter New Horizons’ own record for the closest-ever views of this KBO in November 2015, when New Horizons detected JR1 from 280 million kilometres (170 million miles) away.
Simon Porter, a New Horizons science team member from Southwest Research Institute (SwRI) in Boulder, Colorado, said the observations contain several valuable findings. “Combining the November 2015 and April 2016 observations allows us to pinpoint the location of JR1 to within 1,000 kilometres (about 600 miles), far better than any small KBO,” he said, adding that the more accurate orbit also allows the science team to dispel a theory, suggested several years ago, that JR1 is a quasi-satellite of Pluto.
From the closer vantage point of the April 2016 observations, the team also determined the object’s rotation period, observing the changes in light reflected from its surface to determine that a JR1 “day” is 5.4 hours. “That’s relatively fast for a KBO,” says science team member John Spencer, also from SwRI. “This is all part of the excitement of exploring new places and seeing things never seen before.”
Spencer added that these observations are great practice for possible close-up looks at about 20 more ancient Kuiper Belt objects that may come in the next few years, should NASA approve an extended mission. New Horizons flew through the Pluto system on 14 July last year, making the first close-up observations of Pluto and its family of five moons. The spacecraft is on course for an ultra-close flyby of another Kuiper Belt object, 2014 MU69, on 1 January 2019.