A Bracewell probe is an interstellar probe theorized by Ronald Bracewell in 1960 that is sent to prospective nearby solar systems to study for life, or primitive civilizations.
If the probe finds either, they (it) sends a message back to its parent civilization.
Are we being scanned by a Bracewell probe?
Well, on May 25th, an object the size of a truck passed by Earth in a solar orbit at the distance of the Moon. Verdict?
It’s an old Soviet interplanetary rocket booster.
But is it really?
The unknown visitor came from deep space. It passed nearly as close to the Earth as the moon on May 21st. Its spectrum didn’t match any known asteroid. At a feeble absolute magnitude of +28.9, the traveler must have only been about the size of a truck.
Object 2010 KQ, what are you?
Is this a scouting ship for Stephen Hawking’s hypothesized evil aliens planning a mass invasion of Earth?
No, more likely it is a discarded interplanetary rocket booster abandoned in solar orbit.
The detection is tantalizing nevertheless because we can identify space objects down to a few feet across. That’s the scale of what you might expect any alien probe might be, assuming their technology is comparable to ours. (Forget about those huge motherships in the 1996 film “Independence Day,” the fuel costs are astronomical.)
On the hypothesis that we might have been visited long ago, could there be alien artifacts left behind, perhaps abandoned in solar orbit too?
The fact that we haven’t found anything yet makes it clear that any visiting aliens didn’t do anything obvious to say they came by. But I can make a few cautious extrapolations from how they might have conducted the exploration of our solar system– that is, if they think like us!
That’s the key; if they think like us.
There’s little evidence to suggest that any alien culture would think like us.
But that’s because we only have a sample size of one, us, to go by.