Spacecraft New Horizons in Kuiper Belt

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This 27 December 2018 video is called Spacecraft to go beyond Pluto on New Year’s Day cosmic rock flyby.

A 4 June 2018 Sky News video used to say about itself:

The New Horizons spacecraft is about to leave hibernation to begin preparations for its January 2019 flyby of the Kuiper Belt object (KBO) 2014 MU69, nicknamed “Ultima Thule”.

The flyby, set to occur in the early morning of January 1, 2019, will be the second for New Horizons, following its historic 2015 Pluto flyby.

It will also be the furthest flyby from Earth ever performed by a spacecraft.

Initial searches for a post-Pluto flyby target for New Horizons began in 2011, 4 years before its flyby of Pluto. The New Horizons team was aiming for potential KBOs around 50-100km in diameter.

At first, only large ground-based telescopes were used in the search but were unable to find any KBOs that New Horizons could reach with its limited fuel supply.

Eventually, the Hubble Space Telescope took over the search, and discovered three possible targets for the flyby, given the temporary names “PT1”, “PT2”, and “PT3”, with the “PT” standing for “Potential Target”. PT1 and PT3 were seen as the best targets, while PT2 was dropped due to it being further away from New Horizon’s path than the two others.

Both PT1 and PT3 had their advantages and disadvantages. For example, PT1 would require less fuel to get to than PT3, but is likely smaller than PT3.

On August 28, 2015, the New Horizons team announced they had chosen PT1 – which was given the temporary name “2014 MU69” – as the flyby target. From multiple observations by Hubble and other ground-based telescopes, MU69 was determined to be red, around 30km in diameter, and potentially a binary system.

By observing MU69’s shape as it passed in front of background stars – called on occultation – astronomers found that MU69 may be double-lobed – meaning that it could be comprised of two large, connected sections – or a binary system, composed of two similar objects orbiting each other.

An example of a binary system is Pluto and its largest moon, Charon. Although they are not the same size, both objects orbit around a barycenter – a point of gravity between the two objects.

In October and November 2015, four maneuvers were performed by New Horizon’s hydrazine-fueled engines to set it up for a flyby of MU69 in January 2019.

In 2017, two small correction maneuvers were performed with the engines in order to further refine the flyby. On March 13, 2018, using public input from online polls and user-submitted names, MU69 was given the nickname “Ultima Thule” by the New Horizons team – meaning beyond the borders of the known world.

New Horizons will begin its approach phase of the MU69 flyby on August 16, 2018, when it will begin imaging MU69 and the area around it to begin acquiring data about the KBO and its surroundings. Also, New Horizons will look for potential debris that could pose a hazard to itself, such as moons or rings. Should any potential dangers be found, New Horizons has four planned opportunities to make trajectory changes from early October to early December 2018.

By Lisa Grossman, 10:51am, June 5, 2018:

New Horizons wakes up to begin Kuiper Belt exploration

The spacecraft will fly past a small rock nicknamed Ultima Thule on New Year’s Day

The spacecraft that raced past Pluto is back and ready to explore a whole new world.

NASA’s New Horizons probe woke up at 10:55 p.m. EDT on June 4 after a nearly six-month slumber, and news of the event reached Earth several hours later. The craft is now getting ready to fly past a small Kuiper Belt object called Ultima Thule (SN Online: 3/14/18).

New Horizons went into the last of a series of sleep modes on December 22, 2017, resting before continuing its exploration of the Kuiper Belt, the zone of small icy celestial bodies beyond Neptune (SN: 6/27/15, p. 16).

Hibernation is part of normal spacecraft operations, says mission principal investigator Alan Stern of the Southwest Research Institute who is based in Boulder, Colo. “It saves wear and tear on the system, and it frees up personnel to do flyby planning.”

“IT’S HAPPENING! IT’S HAPPENING!” Stern tweeted in the early hours of June 5. “Flyby preparations for Ultima Thule begin shortly!”

In its next act, New Horizons will fly past the distant rock of Ultima Thule (also known as 2014 MU69) on New Year’s Day in 2019. Earlier observations suggest that Ultima Thule, no more than 30 kilometers long, could actually be two smaller objects orbiting each other (SN Online: 12/12/17). The team will know more when New Horizons’ first images after waking up arrive at Earth in August 2018.

Scientists think that Ultima Thule has existed near its current orbit 6.5 billion kilometers from Earth, at a temperature of –240° Celsius, for most of the solar system’s 4.6-billion-year history. “As such, MU69 will be the most primitive body ever studied by any spacecraft,” the team writes in the June Space Science Reviews.

New Horizons may have seen a glow at the solar system’s edge. The ultraviolet signal may mark a wall of hydrogen where the sun’s influence wanes. By Lisa Grossman, 7:00am, August 9, 2018.