The idea that we might take an active, working spacecraft in the Kuiper Belt and not only repurpose it for a different task (heliophysics) but also dismiss the team that is now running it is patently absurd. Yet this appears to be a possibility when it comes to New Horizons, the remarkable explorer of Pluto/Charon, Arrokoth, and the myriad objects of the Kuiper Belt. NASA’s Science Mission Directorate, responding to a 2022 Senior Review panel which had praised New Horizons, is behind the controversy, about which you can read more in NASA’s New Horizons Mission Still Threatened.
So absurd is the notion that I’m going to assume this radical step, apparently aimed at ending the Kuiper Belt mission New Horizons was designed for on September 30 of 2024, will not happen, heartened by a recent letter of protest from some figures central to the space community, as listed in the above article from Universe Today. These are, among a total of 25 planetary scientists, past Planetary Society board chair Jim Bell, Lori Garver (past Deputy Administrator of NASA), Jim Green (Past Director of NASA’s Planetary Science Division), Candice Hansen-Koharcheck (Past chair of the American Astronomical Society’s Division of Planetary Sciences and Past Chair of NASA’s Outer Planets Assessment Group), author Homer Hickham, Wesley T. Huntress (Past Director of NASA’s solar system Exploration Group), astrophysicist Sir Brian May, and Melissa McGrath (past NASA official and AAS Chair of DPS).
Needless to say, we’ll keep a wary eye on the matter (and I’ve just signed the petition to save the original mission), but let’s talk this morning about what New Horizons is doing right now, as the science remains deeply productive. I like the way science team member Tod Lauer spoke of the spacecraft’s current position in a recent post on the team’s website, a place where “It’s still convenient to think of neat north and south hemispheres to organize our vista of the sky, but the equator is now defined by the band of the galaxy, not our spinning Earth, lost to us in the glare of the fading Sun.”
Places like that evoke the poet in all of us. Lauer points out that the New Horizons main telescope is no more powerful than what amateur stargazers willing to open their checkbooks might use in their backyards. Part of the beauty of the situation, though, is that New Horizons moves in a very dark place indeed. While I have vivid memories of seeing a glorious Milky Way bisecting the sky aboard a small boat one summer night on Lake George in the Adirondacks, how much more striking is the vantage out here in the Kuiper Belt where the nearest city lights are billions of kilometers away?
Image: A Kuiper Belt explorer looks into the galaxy. Credit: Serge Brunier/Marc Postman/Dan Durda
The science remains robust out here as well. Consider what Lauer notes in his article. Looking for Kuiper Belt objects using older images, the New Horizons team found that in all cases, even objects far from the Milky Way’s band appeared against a background brighter than scientists can explain, even factoring in the billions of galaxies that fill the visible cosmos. The puzzle isn’t readily solved. Says Lauer:
…we then tried observations of a test field carefully selected to be far away from the Milky Way, any bright stars, clouds of dust – or anything, anything that we could think of that would wash out the fragile darkness of the universe. The total background was much lower than that in our repurposed images of Kuiper Belt objects – but by exactly the amount we expected, given our care at pointing the spacecraft at just about the darkest part of the sky we could find. The mysterious glow is still there, and more undeniable, given the care we took to exclude anything that would compete with the darkness of the universe, itself. You’re in an empty house, far out in the country, on a clear moonless night. You turn off all the lights everywhere, but it’s still not completely dark. The billions of galaxies beyond our Milky Way are still there, but what we measure is twice as bright as all the light they’ve put out over all time since the Big Bang. There is something unknown shining light into our camera. If it’s the universe, then it’s just as strong, just as bright, as all the galaxies that ever were.
Only New Horizons can do this kind of work. How far are we from Earth? Take a look at the animated image below, which is about as vivid a reminder as I can find.
Image: Two images of Proxima Centauri, one taken by NASA’s New Horizons probe and the other by ground-based telescopes. The images show how the spacecraft’s view, from a distance of 7 billion kilometers, is very different from what we see on Earth, illustrating the parallax effect. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute/Las Cumbres Observatory/Siding Spring Observatory.
With 15 more dark fields slated for examination this summer, New Horizons remains active on this and many other fronts. In his latest PI’s Perspective, Alan Stern notes the eight-week period of observations taking place now and through September. include continued observations of KBOs, imaging of the ice giants, dust impact measurements, mapping of hydrogen gas in the outer heliosphere, analysis using the ultraviolet spectrometer to look for structures in the interstellar medium, and spatial variations in the visible wavelength background. Six months of data return will be needed to download the full set for the planetary, heliospheric and astrophysics communities.
According to Stern, new fault protection software will allow New Horizons to operate out to 100 AU. That assumes we’ll still be taking Kuiper Belt data. Given the utterly unique nature of this kind of dataset and the fact that this spacecraft is engaged in doing exactly what it was designed to do, it is beyond comprehension that its current mission might be threatened with a shakeup to the core team or a reframing of its investigations. I’ve come across the National Space Society’s petition to save the New Horizons Kuiper Belt mission late, but please take this chance to sign it.