New Horizons course correction puts spacecraft on target to Ultima Thule

This composite image of Ultima Thule was taken just 33 hours before the Dec. 2, 2018, course-correction maneuver that fine-tuned New Horizons’ trajectory for its New Year’s 2019 flyby. At left is the full Long Range Reconnaissance Imager or LORRI image, which is 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 2018, 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 although many artifacts from the imperfect star subtractions are visible in this difference image. Ultima was 4.01 billion miles or 6.47 billion kilometers from the Sun and 24 million miles or 38.7 million kilometers from the New Horizons spacecraft when the images were taken.
Caption & Image Credit: NASA / Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute

NASA’s New Horizons spacecraft conducted the most distant ever course-correction maneuver by any vehicle on Sunday, Dec. 2, firing its thrusters for just 105 seconds to adjust its velocity by approximately 2.2 miles per hour.

Mission engineers conducted the maneuver to refine the spacecraft’s course so it meets the goal of closest flyby of Kuiper Belt Object (KBO) Ultima Thule at 12:33 a.m. EST on Tuesday, Jan. 1, from a distance of just 2,200 miles (3,500 km).

New Horizons was 4.03 billion miles (6.48 billion km) from Earth and just 40 million miles from its second target when the maneuver was carried out on Sunday at 8:55 a.m. EST (12:55 GMT). A radio signal confirming its success was conveyed via NASA’s Deep Space Network (DSN) at 5:15 p.m. EST that day.

Travel time for radio signals from New Horizons back to Earth now takes some six hours, with the signals traveling at the universal speed of light.

Up to three more course-correction maneuvers are under consideration by the team in charge of the mission as the spacecraft closes in on Ultima Thule.

Thirty-three hours before the maneuver, New Horizons‘ Long Range Reconnaissance Imager (LORRI) captured 10 individual 30-second exposures of the KBO that it was heading toward, which the mission team combined and released as a single image. Ultima Thule can now be detected against the background of stars without any image processing. When mission scientists subtract the background stars and expand the section of the image containing the KBO, it can be clearly seen.

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