NASA’s New Horizons spacecraft flew past Pluto seven years ago, but the probe’s work is far from done.
New Horizons is still in service in extended mission mode, plunging deeper and deeper into the Kuiper Belt to examine ancient icy mini-worlds in that vast region beyond Neptune’s orbit.
New Horizons was launched in January 2006 and carried out a reconnaissance study of Pluto and its moons in the summer of 2015, culminating in an end dwarf planet flyby on July 14, 2015. This encounter revealed Pluto to be an incredibly diverse world, with towering mountains of water ice and huge plains of exotic nitrogen ice.
But the nuclear-powered probe kept its eyes peeled even after Pluto was in the rearview mirror.
Destination Pluto: NASA’s New Horizons mission in pictures
New horizons then stolen by Arrokotha small Kuiper Belt Object (KBO), Jan. 1, 2019. Arrokoth, which the New Horizons science team discovered in 2014 using the The Hubble Space Telescopeis the most distant and primitive object ever closely explored by a spacecraft.
And there could also be another sneak peek in the future of New Horizons.
At a meeting of NASA’s Outer Planets Assessment Group (OPAG) in June, New Horizons principal investigator Alan Stern of the Southwest Research Institute (SwRI) in Colorado said the spacecraft and its scientific payload were in perfect health. The probe’s lifespan is currently limited only by its supply of nuclear fuel, which is likely enough to keep New Horizons flying until 2040.
And NASA recently granted another mission extension to New Horizons, which will allow the spacecraft to continue until 2025.
“I’m very excited about this second extended mission,” Stern told Space.com. NASA and the New Horizons team are discussing budget numbers for fiscal year 2025, he added.
Main Action Items
On the New Horizons agenda are now a trio of main actions, as approved by NASA. One is to look for another flyby target “and also more KBOs that we can study, not up close, but far away,” Stern said.
Additionally, New Horizons is still transmitting the last bytes of data collected during the Arrokoth flyby in 2019.
“We were delayed, mainly because the Deep Space Network had some improvements. They took antennas apart, and one was down for a year,” Stern said. “We have about 90 percent of the Arrokoth overview [data] in the field, but we want everything, and that takes time. So it’s an important activity.”
Then there’s the centerpiece of New Horizons’ second extended mission – a diversity of sightings in a variety of areas.
“As we fly over the Kuiper Belt“, Stern added, “we are going to do a very interdisciplinary mission in all space sciences – astrophysics, planetary science and heliophysics. We’re going to use this spaceship to do things that really can’t be done unless you have a spaceship there. There’s really never been anything like it… We’re doing the three different space sciences by making New Horizons an observatory for all three purposes.”
For example, in heliophysics, the spacecraft will study “sensor ions”. These charged particles dominate the pressure of the outer heliosphere – the huge bubble of magnetic fields and particles that the sun blows around it – and control where the boundary with the interstellar medium is.
In astrophysics, New Horizons will study the cosmic optical and ultraviolet background, getting a beautiful view beyond obscuring dust and other scattered light sources from the inner regions of the solar system. New Horizons has already produced the most sensitive measurements of these backgrounds to date, with “profound implications for cosmology,” Stern noted.
In the planetary science column, the probe is scheduled to study Uranus and Neptune from unique “high phase angle” geometries, highlighting the significant energy budgets of these planets.
“There’s never been anything really deeply interdisciplinary like New Horizons is going to be over the next three years on an extended mission,” Stern said.
Related: NASA’s New Horizons Pluto spacecraft is still exploring, 50 AU from the sun
The New Horizons team also plans to get time on ground-based telescopes such as Keck and Subaru to find new KBOs to study as the probe passes by them, “or if you have luck and you come across one that’s close enough for us to get to, we’ll have a close flyby,” Stern said.
The New Horizons team uses machine learning to find new KBOs using such scopes. “It turns out to be faster, more accurate, more reliable,” Stern said. Compared to human research, machine learning “is better and finds more KBOs. So it’s a breakthrough that saves us a lot of work and turns out to be a better product.”
Ground observations have shown that there are different classes of KBOs that have different colors and compositions. “So we know there’s a lot of heterogeneity among KBOs,” Stern said. “If we had a flyover of a second KBO, I wouldn’t expect the same at all. It would be a completely different place in Arrokoth.”
KBOs teach scientists about planetesimals, the building blocks of planets thought to exist in protoplanetary disks and debris disks.
The Arrokoth KBO flyby yielded a groundbreaking result, Stern said: that at least some planetesimals formed very slowly, in a process called the local cloud collapse phenomenon. The New Horizons team would like to closely study another KBO, to see if its formation and evolution matches what has been observed at Arrokoth.
“We’re turning this into a machine that does good for astrophysics and heliophysics while doing good for planetary science,” Stern said of New Horizons and its second extended mission. “They are equal partners in science, and this is a first for a planetary science mission.”
Leonard David is the author of the book “Moon Rush: The New Space Race”, published by National Geographic in May 2019. A longtime author for Space.com, David has been reporting on the space industry for more than five decades. Follow us on twitter @Spacedotcom (opens in a new tab) Or on Facebook (opens in a new tab).