Hello this is the Global News Podcast from the BBC World Service. I'm Valerie

Sanderson with your weekly bonus from the Global Story which brings you a single

story with depth and insight from the BBC's best journalists.

There's a new episode every weekday.

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and be sure to subscribe so you don't miss a single episode. Here's my colleague as a date

machinery. When the Titan Submersible was reported missing on its expedition to the Titanic last year, the eyes of the world became

fixed on the recovery mission. But as the prospect of a rescue began to wane, authorities

concluded the vessel had suffered a catastrophic implosion.

Eventually we learnt all five on board died instantly.

It was a tragedy and for the past two weeks the US Coast Guard has been hearing from

numerous witnesses to try to piece together what went wrong. On this episode

we're sifting through the most revealing testimonies. Why did Ocean Gate Staff have concerns?

Was the fatal mission avoidable?

And what could the Titans demise

mean for the future of deep sea exploration? of Deep Sea Exploration. With me today is the BBC Science Editor Rebecca Morrell, who not only has been following every second of the proceedings

but has also been reporting on her passion the deep sea for years.

Rebecca hi thanks for joining. Hello.

We're going to get into the detail of what happened shortly, but first off, let's just

clear something up.

Rebecca, what exactly do we mean when we talk about a submersible?

That's a good question, because it's this word we've been hearing every day, all day for the last few weeks during the public hearing.

...