Space explorer ‘phones home’ six billion kilometres from Earth
A NASA probe has reached the farthest cosmic object ever explored by humankind, revealing new clues to how the planets formed.
Ultima Thule, a space rock 35km long and 14km wide, sits in the dark and frigid Kuiper belt, six billion kilometres from Earth, on the edge of the solar system. The New Horizons probe flew by at 51,500kmh, passing within 3,500km of the surface.
From there, it took 10 hours for an anxiously awaited “phone home” signal to reach mission control at Johns Hopkins Applied Physics Laboratory in Maryland.
As cheers erupted, Alice Bowman, the mission operations manager, said: “We have a healthy spacecraft. We’ve just accomplished the most distant fly-by. This science will help us understand the origins of our solar system.”
A blurry initial image sent back of Ultima Thule showed a white object resembling a bowling pin, or a peanut, and rotating like a propeller.
The fly-by was more than one-and-a-half billion kilometres beyond Pluto, previously the farthest space object ever visited.
Scientists hope fresh images of Ultima Thule will help them learn about the ancient building blocks of planets. Along with other bodies in the Kuiper belt, it is a relic from the early solar system, having been deeply frozen and perfectly preserved. It takes 295 years to orbit the sun.
Seven instruments on the New Horizons will be used to detect the chemical composition of its atmosphere and terrain. Beaming all the discoveries back will take two years.
“Everything we are going to learn, from its composition to its geology, to how it was originally 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,” said Alan Stern, lead planetary scientist for New Horizons.
Scientists are still unsure, until they see further images, if the object is a single body, or two orbiting each other.
Ultima Thule was discovered in 2014 with the help of the Hubble Space Telescope. It was originally called 2014 MU69, but renamed after Thule, a mythical island in medieval literature. The space agency said “Ultima Thule” meant “beyond Thule” and was intended to indicate “beyond the borders of the known world”.
Brian May, the Queen guitarist, who has a PhD in astrophysics, is a participating scientist in the mission. He also wrote a song in honour of the probe.
After the fly-by, he said: “This is a night none of us are going to forget. (©Daily Telegraph, London)