Sensors detect life on the vessel, but still no response to our hails.

Scientists differ about the strength of this argument, but even at its best it is very different from actually detecting life elsewhere.

But you might be skeptical about our ability to detect life elsewhere, especially life different from the kind we know.

It would have been foolish to send instruments that could not even detect life on Earth.

We have no instruments that will actually detect life.

The research helped resolve ambiguous indications that the spacecraft had detected biological life.

This could provide a method of detecting life on Mars.

Several indirect methods for detecting extraterrestrial life have been proposed in the prior literature.

However, it won't attempt to detect life in the way that the Viking landers did.

Just because we don't detect life doesn't mean there's nothing threatening.