Centauri Dreams is following the Pioneer 10 story with great interest, and not just in terms of the anomalous effects that continue to keep this mission in the news. Ponder that Pioneer 10 was launched in 1972 and consider that even with the technologies of its day, the probe may still be able to communicate with Earth. We have learned so much in the interim about hardened electronics and autonomous self-repair that there is reason to believe probes to even remoter locations in the Kuiper Belt and beyond are feasible providing we can solve the propulsion conundrum.
The next attempt to contact the venerable spacecraft would occur in March, if it occurs at all, and you can hear more about it in an interview conducted by Planetary Radio. The guest is JPL senior research scientist John Anderson, who discusses the mission, its current communications challenges, and the possible reasons for what appears to be its deceleration as it moves away from the Sun.
Or is the effect really a deceleration? A new paper called “Pioneer Anomaly: What Can We Learn from LISA?” has just appeared on the arXiv site, making the case that there is a second explanation: an anomalous blueshift of the radio signal. Authors Denis Defrère (University of Liege) and Andreas Rathke (Institute for Theoretical Physics, University of Cologne) examine the effects such a blueshift might have on the upcoming Laser Interferometer Space Antenna (LISA) mission to detect gravitational waves.
It would be useful if LISA could be used to verify the Pioneer data; it appears to be the earliest spacecraft that could make such an attempt. But the authors’ conclusion is discouraging: the anomalous blueshift is always overwhelmed by one or another noise source in the LISA interferometer.
And if LISA cannot test the Pioneer Anomaly, what can? From the paper:
More promising – and probably mandatory if the Pioneer anomaly represents a force and not a blueshift – would be a test in the outer Solar system by radio-tracking of a deep space vehicle with very well known onboard systematics. Preferably this would be a dedicated mission to explore the anomaly although a planetary exploration spacecraft which has been designed with the secondary goal to test the Pioneer anomaly could already gain considerable insights. The analysis of the full archive of Pioneer 10 and 11 Doppler data, that is currently being initiated, might further help to identify mission scenarios that are especially suited for a test of the anomaly.
It’s too late for New Horizons, of course, but any followup Pluto/Kuiper Belt mission would have such an opportunity. On that score, see T. Bondo, R. Walker, A. Rathke et al., “Preliminary Design of an Advanced Mission to Pluto,” scheduled to appear in the proceedings of the 24th International Symposium on Space Technology and Science, Miyazaki, Japan, June 2004, and already available online (PDF warning).
What about the notion of launching a vehicle dedicated entirely to this mission. If you could do this with a smallsat of some variety, you might be able to actually get out to a respectible distance pretty quickly without an enormous booster. What are your thoughts on this?
I think it’s a good idea, though the notion of piggybacking several missions into one is irresistible given the current budget constraints. But yes, it’s certainly a workable idea if the funding could be found. What would have to happen first is a consensus in the scientific community that there is something compelling to be learned from the Pioneer Anomaly. If there is a real possibility of some new physics here, the interest in such a mission will mount.
If the satellite can be made small and light enough, I was thinking it might be something for a university (or university consortium) to tackle. I don’t have figures handy for what a small probe would run, but at a nano size, you can start getting a pretty big boost from current launchers.
Yes, absolutely, once we get to the nano-scale in terms of practical mission hardware, all kinds of things open up. Pushing a 1000 kg payload to Alpha Centauri is one thing; pushing what Robert Freitas talks about as a ‘needle’ probe (i.e., about the size of a sewing needle, but stuffed with nanotech) is quite another. The nanotechnology revolution, assuming it plays out in the direction it seems to be going, is going to create abundant opportunities for radical spacecraft designs. Or, as Princeton’s Edward Belbruno once told me, ‘Get it down to nano-size and you can push it with a flashlight!’