I'm Rory Stewart and I grew up wanting to be a hero and I'm still fascinated by the ideas of heroism.

In my new series, I'm taking in the long sweep of history from Achilles to Zelensky and asking, what is a hero?

Simply doing your job, being a decent human being.

A true hero is someone who just kind of shines by their own light,

and that light is to be recognised by others.

The Long History of Heroism with me, Rory Stewart.

Listen on BBC Sounds.

Thank you for downloading from the BBC.

For details of our complete range of podcasts and our terms of use,

go to BBCworldservice.com slash podcasts.

You're with Discovery on the BBC. I'm Jason Palmer.

It's been almost a half century that we've been listening to the universe

in the hunt for evidence of intelligent alien life,

so far without success. The hunt is called the hunt for evidence of intelligent alien life, so far without

success. The hunt is called the search for extraterrestrial intelligence, or SETI. Leading that hunt

is the SETI Institute, based in the San Francisco Bay Area. About 400 kilometers north lies the vast

Allen array, a collection of 42 linked telescopes, which SETI uses to listen out for alien communications.

But this flagship facility was forced to shut down last April for lack of funds.

Donations from members of the public, former astronauts, and even Hollywood actress Jody Foster

scraped together enough money to keep going for a few more months.

But then what? Can SETI survive without sustainable funding?

What keeps the researchers themselves from losing hope? And just how has the hunt for alien signals

...