Of the many interesting questions Nick Nielsen raised in last Friday’s post, the one that may be most familiar to the interstellar community is the question of potential breakthroughs. What happens if an unexpected discovery in propulsion makes all the intervening stages — building up a Solar System-wide infrastructure step by step — unnecessary? If we had the kind of disruptive breakthrough that enabled starflight tomorrow, wouldn’t the society that grew out of that capability be fundamentally different than one in which starflight took centuries to achieve?

I was mulling this over yesterday when I read Pluto-bound Probe Faces Crisis, a short article in Nature that several readers had passed along. With the New Horizons probe pressing on for a close-pass of Pluto/Charon next year, the assumption all along has been that it would make a course correction after the encounter to set up a flyby of a Kuiper Belt Object (KBO). The trick there is that the New Horizons team is running out of time to find the right KBO. The sense of urgency is revealed in the fact that mission scientists have asked for 160 orbits of observing time on the Hubble instrument, which the article calls a ‘rare request’ for an already operational mission.

Alexandra Witze sums up the reason for the delay in identifying a target in the Nature story:

In theory, project scientists should have identified a suitable KBO long ago. But they postponed their main search until 2011, waiting for all the possible KBO targets to begin converging on a narrow cone of space that New Horizons should be able to reach after its Pluto encounter. Starting to look for them before 2011 would have been impossible, says [mission co-investigator Will] Grundy, because they would have been spread over too much of the sky.


The Voyagers, Galileo, New Horizons and their ilk represent a familiar evolutionary model of our expansion into the outer Solar System as opposed to the kind of disruptive breakthrough Nick was speculating about. In this model, we learn from mission to mission, making each more capable, adding technologies that can get instruments to their destinations at a faster clip. We can’t predict disruptive technologies, but we can see a rational line of development of current tech as we tune up our deep space craft, one in which the ongoing New Horizons issues play a major role.

Image: Artist’s impression of the New Horizons spacecraft encountering a Kuiper Belt object. The Sun, more than 4.1 billion miles (6.7 billion kilometers) away, shines as a bright star embedded in the glow of the zodiacal dust cloud. Jupiter and Neptune are visible as orange and blue “stars” to the right of the Sun. Although you would not actually see the myriad other objects that make up the Kuiper Belt because they are so far apart, they are shown here to give the impression of an extensive disk of icy worlds beyond Neptune. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

The next year is going to be filled with New Horizons news and, let’s hope, a resolution of the KBO issue. Fifty new KBOs have thus far been identified in the hunt, which has used the resources of the 8.2-metre Subaru Telescope in Hawaii and the 6.5-metre Magellan Telescopes in Chile. None, as it turns out, is close enough to New Horizons’ trajectory to make it feasible given the constraints on the spacecraft’s ability to maneuver. And as I’ve mentioned in these pages before, the search field is tricky, looking directly out along the plane of the galaxy, which means the faint signature of a KBO is readily lost in the starfield. The good news is that by adding Hubble into the mix — and a decision on this won’t be reached until June 13 — the chances of a detection soar over what they would be using ground-based telescopes alone.

Make no mistake, even a long-distance observation of a KBO from New Horizons’ 21-centimeter telescope would trump what we can see from Earth orbit, but obviously a much closer look at a primordial survivor from the Solar System’s early history would be preferable. We wait and hope for the best. Meanwhile, we in the interstellar community should be tracking this mission with great interest. New Horizons is pushing into terra incognita with instruments designed for the job, and represents, as Michael Michaud recently commented to me, a more relevant transition to our deep space future than the Voyager spacecraft. It should energize our designs for future craft that will push further into the Kuiper Belt and beyond. This incremental model works, and if along the way a disruptive breakthrough occurs, then so much the better.