NASA's Mission to Pluto and the Kuiper Belt
With just 29 days to go before making space exploration history, NASA's New Horizons spacecraft performed a short but record-setting course-correction maneuver on Dec. 2 that refined its path toward Ultima Thule, the Kuiper Belt object it will fly by on Jan. 1.
Just as the exploration of Ultima Thule will be the farthest-ever flyby of a planetary body, Sunday's maneuver was the most distant trajectory correction ever made. At 8:55 a.m. EST, New Horizons fired its small thrusters for 105 seconds, adjusting its velocity by just over 1 meter per second, or about 2.2 miles per hour. Data from the spacecraft confirming the successful maneuver reached the New Horizons Mission Operations Center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, through NASA's Deep Space Network, at 5:15 p.m. EST.
The maneuver was designed to keep New Horizons on track toward its ideal arrival time and closest distance to Ultima, just 2,200 miles (3,500 kilometers) at 12:33 a.m. EST on Jan. 1.
At the time of the burn New Horizons was 4.03 billon miles (6.48 billion kilometers) from Earth and just 40 million miles (64 million kilometers) from Ultima – less than half the distance between Earth and the Sun. From that far away, the radio signals carrying data from the spacecraft needed six hours, at light speed, to reach home.
The team is analyzing whether to conduct up to three other course-correction maneuvers to home in on Ultima Thule. Follow New Horizons to Ultima at http://pluto.jhuapl.edu/Mission/Where-is-New-Horizons.php.
Ultima Comes into Clearer View: This composite image of Ultima Thule was taken just 33 hours before the Dec. 2 course-correction maneuver that fine-tuned New Horizons' trajectory for its New Year's flyby. At left is the full Long Range Reconnaissance Imager (LORRI) image (an average of 10 individual 30-second exposures) with a yellow circle centered on the location of Ultima Thule. Unlike the LORRI images taken in August through October, Ultima is now evident among the many background stars even without further processing. Nevertheless, Ultima really stands out after subtracting the background stars; the region within the yellow box has been expanded in the star-subtracted version of the image on the right (many artifacts from the imperfect star subtractions are visible in this difference image).
Ultima was 4.01 billion miles (6.47 billion kilometers) from the Sun and 24 million miles (38.7 million kilometers) from the New Horizons spacecraft when the images were taken. "As the New Horizons spacecraft closes in on its target, Ultima Thule is getting brighter and brighter in the LORRI optical navigation images," said Hal Weaver, New Horizons project scientist from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. "It's now standing out much more clearly among the sea of background stars."