NASA’s New Horizons spacecraft has now traveled half the distance from Pluto to its next target in the outer reaches of our solar system. The probe reached that milestone on April 3 when it was 486.19 million miles (782.45 million kilometers) beyond Pluto which is the same distance from its next target, 2014 MU69.
On April 7, New Horizons will also reach the halfway point in time between its closest approach to Pluto (which occurred July 14, 2015) and MU69 with an estimated time of arrival of January 1, 2019.
Scientists say that the nearly five-day difference between the halfway point in distance and the halfway point in time is due to the gravitational tug of the sun. New Horizons is actually getting slightly slower as it pulls away from the sun’s gravity, so the spacecraft crosses the midpoint in distance a bit before it passes the midpoint in time.
Launched in January 2006 from Cape Canaveral, Florida, New Horizons is currently 3.5 billion miles (5.7 billion kilometers) from Earth. At that distance, a radio signal sent from Earth traveling at light speed needs about five hours and 20 minutes to reach the spacecraft. New Horizons will begin a new 157-day period of hibernation later this week after being “awake” for nearly two-and-a-half years.
In addition to its historic Pluto encounter and 16 subsequent months of relaying the data from that encounter back to Earth, New Horizons has made breakthrough, distant observations of a dozen Kuiper Belt objects, collected unique data on the dust and charged-particle environment of the Kuiper Belt, and studied the hydrogen gas that permeates the vast space surrounding the sun, called the heliosphere.
ABOVE IMAGE: An artist's impression of NASA's New Horizons spacecraft, en route to its January 2019 encounter with Kuiper Belt object 2014 MU69. Credits: NASA/JHUAPL/SwRI