Mysterious rock carries secrets of the universe frozen in time

For 13 years a NASA spacecraft the size of a grand piano has barrelled away from Earth at about 51,000km/h.

New Horizons project scientist Hal Weaver addresses a press conference after it was confirmed the spacecraft had completed a fly-by of Ultima Thule.

For 13 years, a NASA spacecraft the size of a grand piano has ­barrelled away from Earth at about 51,000km/h.

On Tuesday, on the very edge of our solar system, its mission reached its climax when the New Horizons probe screamed past a mass of rock that has drifted undisturbed for four billion years.

The rendezvous, about six billion kilometres from Earth, marked a historic fly-by in an ­attempt to map the most distant, most primitive cosmic body ever explored by mankind.

New Horizons’ mission was to collect data, including thousands of photographs, of Ultima Thule, a frozen world on the Kuiper belt about 1.6 billion kilometres ­beyond the furthest known major planet, Neptune.

Ultima Thule receives only a tiny amount of light from the sun and scientists believe it has been frozen since the dawn of the solar system when the planets, ­including Earth, were formed from a vast cloud of dust and gas.

GRAPHIC: The mission so far

As the clock counted down to the fly-by, excitement built at mission control in Maryland. “Are you psyched?” asked Alan Stern, the head of the project, surrounded by children waving American flags.

The closest approach came just after midnight local time.

The excitement was fused with anxiety: a collision with an object as small as a grain of rice could have spelt disaster. “We’re very confident in the spacecraft, and we’re very confident in the plan that we have for the exploration of Ultima,” Professor Stern told reporters earlier in the week, but ­admitted: “We only get one shot.”

After 10 excruciating hours of radio silence, confirmation ­arrived that the mission was a success. Early images appeared to confirm Ultima Thule is small and rocky. The name comes from the Latin for “beyond the known world” and was adopted by the New Horizons team after they asked for suggestions from the public. Its official name is 2014 MU69. It is one of a vast cloud of Kuiper belt objects. Others include the dwarf planet Pluto and up to one trillion comets.

Professor Stern said: “Everything we are going to learn about Ultima, from composition to ­geology to how it was  assembled, whether it has satellites and an ­atmosphere and those kinds of things, are going to teach us about the original formation conditions of objects in the solar system.”

Ultima was discovered in 2014 by the Hubble Space Telescope; no Earth-based observatory has been able to pick it out of the night sky.

The New Horizons probe was launched in 2006 and has already transformed our understanding of the solar system. Its primary mission was to explore Pluto and over six weeks in 2015 it delivered more information about the dwarf ­planet than had been gathered in the previous eight decades. Pluto, it revealed, has snowfalls and mountains of ice rearing 3.2km high. The exploration of Ultima Thule — a target that had not been discovered when the spacecraft launched — became a secondary mission in 2016.

Jim Bridenstine, NASA’s chief administrator, tweeted: “Today New Horizons flew by the most distant object ever visited by a spacecraft and became the first to directly explore an object that holds remnants from the birth of our solar system. This is what leader­ship in space exploration is all about.”

On Monday another NASA spacecraft entered orbit around the asteroid Bennu, 113 million kilometres from Earth. At 490m across, it is the smallest celestial body ever orbited by a spacecraft.

The Times