[madeuptempacct]

I have been obsessing over Oumuamua as well, but there's just not that much information, and we won't be getting more. Then there was the fact that it was tumbling and wasn't emitting anything - one would expect radar scans or radio transmissions, or at least something.

[jobigoud]

> Then there was the fact that it was tumbling and wasn't emitting anything

There is a range of the radio spectrum we can't really practically measure: the very, very low frequencies. Consider a nanohertz signal. Period of each sine wave: 31 years. You might also need an antenna the size of the solar system to grab anything.

[xj9]

passive sensors are safer if you are sending probes into unknown territory populated by potentially violent aliens.

[java-man]

violent aliens are much closer than you think ;-)