Press. Voanews.
After studying a
space rock some 4 billion miles (6.4 billion km) from Earth, NASA's New
Horizons spacecraft set off on a new hunt for moons in the solar system's most
distant edge, searching for clues on our solar family's creation, scientists
said on Thursday.
The piano-sized
probe is traveling deep into the ring of celestial bodies known as the Kuiper
Belt looking for small, icy moons that spun off the snowman-shaped Ultima Thule
formation, a pair of icy space rocks that fused in orbit billions of years ago.
"If we've
seen bodies one and two, the question is what about bodies three, four and
five?" Mark Showalter, a New Horizons investigator, said during a news
conference at the Johns Hopkins Applied Physics Laboratory in Maryland.
New Horizons on
New Year's day came within 2,200 miles (3,500 km) of Ultima Thule, which
represents a pristine time capsule dating to the birth of the solar system. The
fly-by marked the farthest close encounter of an object within our solar
system.
Since then, the
probe has sent images revealing Ultima Thule to be a contact binary — two
bodies that formed separately and then got stuck together. The formation,
resembling a red-hued snowman — caused by irradiated ice — is just over 21
miles (34 km) long.
Scientists
deduced that the conjoined bodies — one named Ultima and the other Thule — were
once part of a cloud of smaller, rotating space rocks that eventually bound
together into two larger bodies orbiting at a much slower speed.
"We're
looking for the objects that put the brakes on these objects," Showalter
said. Finding the moons, which would orbit Ultima Thule up to 500 miles (800
km) from its surface, would also reveal details about the space rock's mass and
density.
The spacecraft,
now 3 million miles (5 million km) beyond Ultima Thule, will ping back more
detailed images and data in the coming weeks, NASA said.
Since its launch
in 2006, New Horizons has traveled 4 billion miles (6.4 billion km) to the
solar system’s edge to study the dwarf planet Pluto, its five moons and
hundreds of icy Kuiper Belt objects.
Scientists had
not discovered Ultima Thule when the probe was launched, according to NASA,
making the mission unique in that respect. In 2014, astronomers found the rocky
formation using the Hubble Space Telescope and the following year selected it
for New Horizon’s extended mission.
While the
mission marks the farthest inspection of an object in our solar system, NASA’s
Voyager 1 and 2, a pair of
deep-space
probes launched in 1977, have reached greater distances on a mission to survey
extrasolar bodies. Both probes are still operational.
Reuters.