As the New Horizons spacecraft races towards interstellar space, it has now reached a historic milestone. On April 17, 2021, New Horizons passed 50 astronomical units, or 50 times the distance from Earth to the sun. It’s only the 5th spacecraft to reach that distance, join Voyagers 1 and 2 and Pioneers 10 and 11.
“Although four other missions reached this distance in the 20th century, none were in perfect health, but New Horizons is,” said Alan Stern, New Horizon principal investigator. on Twitter. “This is a great testament to the skill, care and attention to detail of those who designed and built New Horizons and those who have been the flight crew for over 15 years now.”
This summer marks six years since New Horizons flew past Pluto and its moon system in July 2015.
To celebrate the achievement of this new distance marker, scientists sent instructions to New Horizons a few months ago to try to visualize the location of another deep space traveler, Voyager 1, now in interstellar space. Although Voyager 1 is far too faint to be seen directly in the image, its location is precisely known thanks to NASA’s radio tracking.
“That’s a terrifyingly beautiful image to me,” said Stern.
Converting the AU scale to one that we are more familiar with, New Horizons is now nearly 5 billion miles (7.5 billion kilometers) away. This means that communication with the spacecraft takes a lot of time
At the time of the Pluto flyby, two-way communication between New Horizons and Earth required a nine-hour round trip – 4.5 hours to the spacecraft and another 4.5 hours back. Since radio signals travel at a light speed (186,000 miles per second, 300,000 km per second), this is an example of Pluto’s great distance from Earth, nearly three billion miles (4 billion km). And at the current distance, it will take 7 hours for the signals to reach the distant spacecraft, and another 7 hours for the control team on Earth to find out if the message was received.
“Working with a spacecraft this far away is challenging,” Alice Bowman told me in 2016 for my book “Incredible Stories From Space.” Bowman is the New Horizons mission operations manager at the Johns Hopkins Applied Physics Laboratory, where New Horizons is built and operated. “I always say that you need a split personality when you work in ops (Mission Operations) because of all the variations over time. If you’re sending a real-time command from Earth, you need to know where the spacecraft will be in the future. ”
The New Horizons team offered another way of imagining how far 50 AU is: think of the solar system built on a neighborhood street; the sun is one house to the left of “home” (or the Earth), Mars would be the next house to the right, and Jupiter would be just four houses to the right. New Horizons would now be 50 houses down the street, 17 houses beyond Pluto.
New Horizons is far from finished with its mission. After the flight from Pluto, the spacecraft took a close-up of a Kuiper belt object (KBO) for the first time on New Year’s Day 2019 as it flighted past Arrokoth. From its unique spot in the Kuiper Belt, New Horizons makes observations that can’t be made anywhere else, even the stars look different from the spacecraft’s point of view.
New Horizons collected data on the solar wind and space environment in the Kuiper Belt, and scanned for other Kuiper Belt objects, with a view to visiting an object that emerges along the way, “within range of fuel.” Stern said on Twitter. This summer, the mission team will ship a software upgrade to enhance New Horizons’ scientific capabilities. For future exploration, the spacecraft’s nuclear battery will need to provide enough power to run New Horizons through the late 2030s.
Further reading and more images: JHUAPL
