This is John Bachelor, conversation with asteroid hunter Dante Loretta of the University of Arizona about the tension around the mission to take a sample of asteroid Bennu,

to take that sample by landing in a zone

that was filled with skyscraping boulders to lose everything if you hit the

boulder and tip sideways or other catastrophes lose everything. Here is the challenge as by as seen by the professor and his

colleagues in the final moments of Benno.

More of this later tonight. Yeah, it was chaos early on.

We didn't have a good series of quantitative metrics.

We were kind of going with our gut.

I think we had gotten a little complacent with

the beach idea. We didn't think it was going to be that big of a challenge. The

engineers had come up with an algorithm that could just feed into the shape model of

the asteroid and it would kick out

the safest place to go and get your sample and that is not at all what it was.

The surface is so rugged it's hard to imagine. I talk about exploring it in virtual 3D it's like being in an abandoned

city with these skyscrapers everywhere these giant boulders just tower everywhere

and we have to precision park the spacecraft.

So the first thing we had to do was replace that laser tag with what we call bullseye tag.

We had to upgrade the flight software to make the spacecraft smarter so that it could actively guide itself

away from hazards and towards a safe area.

And what did safe mean?

It needed to be relatively flat. We were really worried about coming down on a slope and tipping the

spacecraft over and crashing into the surface. This is what the first Hayabusa mission did.

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