WASHINGTON — NASA reports that its record-breaking space probe, the New Horizons, has reached another impressive milestone.
On 17 April the half-ton craft became only the fifth man-made machine to fly more than 50 astronomical units into deep space.
That's 50 times the distance from Earth to the Sun, for a total of 7.5 billion kilometers from Earth.
At that distance, it takes commands sent from Earth at the speed of light, a whopping 7 hours to reach the probe; and scientists have to wait another seven hours to hear if the probe received the commands.
Launched in 2006, the New Horizons is much newer than Earth's other deep-space probes, the two Voyager and two Pioneer spacecraft launched between 1972 and 1977.
At a travelling speed of 58,000 kilometers per hour, it is also the fastest machine ever made.
New Horizons became the first probe to study the distant planet of Pluto, and the first to study objects in the Kuiper Belt — a huge disk of mostly ice chunks that ring the outer reaches of our solar system.
It also filmed the first video of an off-Earth volcano when it flew by Jupiter's moon, Io.