Hide and seek in outer space highlights a battle here on Earth
Voyager's mix of tenacity and discovery should worry its science icon competitors
Opinion The true measure of technology is not how well it matches human intelligence, but how well it survives human stupidity. Humanity's most iconic robots, the Voyager space probes, seem to be up to that job. Nearly 20 billion kilometers from home and nearly 50 years in deep space, Voyager 2 has just been told to point its antenna away from Earth and await further orders.
You may think you've tasted the profound bitterness of disabling the network on a remote machine. Not like this, you haven't. It's like dropping your phone down the Kola Superdeep Borehole and wondering why Find My Device won't work.
But wait – it's not game over. The Deep Space Network (DSN) that communicates with our mechanical explorers already picked up the Not Dead Yet signal, and then got full service back in short order. Even without that, confidence was high that the antique astro automaton would fix the problem by itself in time.
There are two reasons Voyager 2 can call home from the edge of the Solar System more reliably than a kid in college, and many more why that matters so much. The first reason is that the spacecraft combines the over-engineering of the past with the flexibility of the new. You might think Voyager would be the weakest signal the DSN has to deal with, being so old and so far away, but radio engineering is subtle.
A number of more recent and much more local spacecraft are actually weaker – including the MAVEN Mars orbiter and, during its life, the Kepler space telescope. Modern storage gives them long observation periods during which they just need very low-speed housekeeping telemetry via very low gain antennas. Voyager was built around one big antenna and the engineering limitations of 50 years ago. Those 50 years have seen huge improvements in digital methods to improve radio links, both on the ground and in space - Voyager was designed for software updates. Old fashioned muscle and new brains: even if things go skew-whiff. The system has slack.
The second reason is forethought. While the Voyagers have thruster fuel and electrical power, they are designed to do a periodic realignment of their orientation by means of the Sun and the star Canopus [PDF] – neither of which is going to randomly throw out dodgy instructions. Plus, the basic idea is that if you point your high-gain antenna at the Sun from that sort of distance, the Earth will be in very close proximity. Clever, simple, reliable. This idea is universal in deep space missions, where the default if customer support isn't answering is: Assume the worst, go into safe mode, and find home. With the Voyagers, we know this can work for half a century.
This combination of longevity in the face of the vastness of space, time, and finger trouble, combined with the huge and dazzling haul of science, has kept the Voyagers in the headlines. With most of the instruments powered down on both Voyagers and just a trickle of data coming back, it's tempting to see them being kept alive more from sentiment than science – tempting, but wrong. Both are in the vanguard of NASA's Heliophysics Mission fleet, the biggest assembly of spacecraft you've never heard of, and both report conditions at the interface between the Sun's environment and the interstellar medium that raise more questions than answers.
Which is what you want from science, not just space science. That's from two elderly machines: since they were launched, their descendents in sky and on Earth have mapped billions of stars, found thousands of exoplanets, photographed black holes, and turned the entire cosmos into a bejewelled laboratory.
At some point, we'll have to send probes designed explicitly to follow up on this. Then again, virtually all missions beyond Mars have been follow-ups to Voyager, bringing increasingly sophisticated instruments to the Jupiter and Saturn systems. Uranus and Neptune await (if NASA can get its act together.) It'll be a very long time before we close the book on the Voyagers.
Compare that with the other great popular icon of science, the Large Hadron Collider. We all know its crowning glory was the confirmation of the Higgs Boson. What else? There's a bunch of exotic particles called pentaquarks, the significance of which is unclear. Another productive area of the LHC has been setting bounds on theories – essentially making precise measurements that show that something isn't there. Got a bright idea for dark matter? Does it make a prediction that the LHC could confirm or deny? The LHC will deny it for you. Try making headlines out of that.
Astrophysics has always been more charismatic than particle physics, and science shouldn't be a beauty pageant
This is all good stuff, but it raises two questions: where does it take us, and can we afford to go there? The LHC has just had a big revamp upping its capabilities, but there's little sense of new pathways to new physics. Indeed, the LHC is vulnerable to other people doing experiments that limit what it can hope to achieve. This one, involving a few thousand molecules in a vacuum chamber being prodded by lasers, strongly suggests that even if a class of phenomena of interest to the LHC exist, they do so at energy levels far higher than can be achieved.
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That experiment took place in an ordinary university lab on an ordinary budget: no wonder the proposed successor to the LHC, the FCC or Future Circular Collider, is no shoo-in for its €20 billion price tag. The LHC was guaranteed to prove or disprove the Higgs; the FCC lacks such a clear goal. That doesn't help.
Astrophysics has always been more charismatic than particle physics, and science shouldn't be a beauty pageant. It's an open question which discipline will best serve the big questions in physics – dark matter, dark energy, quantum gravity. Voyager and its descendents have never made a better case for staring at the stars rather than a hole in the ground: physicists need to accelerate their story, not just their hadrons. ®