To search or not to search
Stigma aside, SETA still has its detractors. One issue is timing. The more time an artifact spends in the Solar System, the less likely it is to survive to the present day unscathed. On geologically active worlds, surface artifacts would be destroyed (or at least buried) by volcanism, tectonics, and erosion. Even on inactive worlds, asteroid impacts could destroy most artifacts within hundreds of millions of years. And orbiting artifacts, like lurkers, might eventually be knocked out of their orbits or damaged by impacts and radiation. This makes the long lifetime of the Solar System a double-edged sword: The farther back in the past you consider, the more time alien civilizations would have had to arise and send probes in our direction — but the slimmer the odds that any resulting artifact would have survived to this day.
Another argument is that the odds of any of this happening in the first place — intelligent extraterrestrials existing, intelligent extraterrestrials leaving some piece of technology within the Solar System, and our being able to detect it — are too slim to be worth investigating.
Haqq-Misra responds that there’s no way to know that for sure. As long as his ideas are potentially feasible, he argues, it’s worth testing them to try to learn something concrete.
“I don’t like to assign likelihoods,” he adds, “until we have data.”
The future
SETA researchers have a few milestones they hope to achieve in the not-so-distant future. One is to check whether any artificial structures larger than 10 meters (33 feet) exist on any solid surfaces within the Solar System, which would be no small feat. Another goal is to search thoroughly for any waste heat that might be emitted by technological artifacts on these worlds.
Haqq-Misra is especially excited at the prospect of more machine learning studies of planetary surfaces as well as searches for technosignatures at gravitationally stable regions called Lagrange points, where artifacts would be able to more easily sustain orbits for long periods of time. But these are only a few projects, and SETA is just getting started.
“At this stage,” Haqq-Misra says, “we should do it all.”