NASA has released new images and data on the Kuiper belt object (KBO) 1994 JR1 from the New Horizons spacecraft.
This image of 1994 JR1 was taken by New Horizons’ LORRI camera in April 2016. The feature in the top left is an internal camera reflection caused by illumination by a very bright star just outside of LORRI’s field of view. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.
1994 JR1 was first spotted in 1994 with the 2.5-m Isaac Newton Telescope at the Roque de los Muchachos Observatory, La Palma, Canary Islands.
This KBO is also a so-called plutino, a trans-Neptunian object in 2:3 mean-motion resonance with the gaseous giant planet Neptune. According to astronomers, Pluto is the largest known plutino.
1994 JR1 is about 90 miles (150 km) in diameter and has an absolute magnitude of 7.6.
Taken with New Horizons’ LORRI instrument on April 7-8, 2016, from a distance of about 69 million miles (111 million km), the new images of 1994 JR1 shatter spacecraft’s own record for the closest-ever views of this object in November 2015, when the spacecraft detected it from 170 million miles (280 million km) away.
“New observations contain several valuable findings,” said New Horizons team member Dr. Simon Porter from the Southwest Research Institute. “Combining the November 2015 and April 2016 observations allows us to pinpoint the location of 1994 JR1 to within 600 miles (1,000 km), far better than any small KBO.”
“The more accurate orbit also allows our team to dispel a theory, suggested several years ago, that 1994 JR1 is a quasi-satellite of Pluto.”
The New Horizons team also determined the object’s rotation period, observing the changes in light reflected from its surface to determine that it rotates once every 5.47 hours.
New Horizons science team used light curve data – the variations in the brightness of light reflected from the object’s surface – to determine 1994 JR1’s rotation period of 5.47 hours. Image credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute.
“1994 JR1 has a rough surface with a 37o mean topographic slope angle and has a relatively rapid rotation period of 5.47 hours,” the scientists said. “1994 JR1 is currently 2.7 astronomical units from Pluto; our astrometric points enable high-precision orbit determination and integrations which show that it comes this close to Pluto every 2.4 million years, causing Pluto to perturb 1994 JR1.”
“These observations are great practice for possible close-up looks at about 20 more ancient KBOs that may come in the next few years, should NASA approve an extended mission,” added team member Dr. John Spencer, also from the Southwest Research Institute.
The team’s findings will be published in the Astrophysical Journal Letters, but have been published on arXiv.org ahead of time.
According to NASA, New Horizons is currently 3.24 billion miles (5.21 billion km) from Earth and 230.5 million miles (371 million km) beyond Pluto, with all systems healthy and operating normally.
It is on course for an ultra-close flyby of the Kuiper Belt object 2014 MU69 in 2019.
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Simon B. Porter et al. 2016. Red, Rough, Fast, and Perturbed: New Horizons Observations of KBO (15810) 1994 JR1 from the Kuiper Belt. ApJL, submitted for publication; arXiv: 1605.05376
