This is John Batchelor, a conversation with Bob Zimmerman about Beppy Colombo, an ESA

Jackson Mission to Mercury, the innermost of the rocky and maybe wet planets.

There's always the speculation about Mercury having ice

at the North Pole that's forever shielded from the sun's heat.

Beepi Colombo, however, ran into a problem with its electric thrusters.

It has challenged the engineers who have come up with a solution, used the planets whipping around flybys. It'll fly by Earth, Bob tells me later this week.

Use those planets an additional boost delaying the arrival in the mercury orbit for a year, but satisfying all the

engineering expectations of thrusters now at 90%. Clever. I admire those engineers.

Give them a challenge.

They love it.

Pepi Colombo, due now in 2026 into orbit around Mercury.

An innermost planet, maybe the shell of an original planet,

the core, unknown. Need more. More of this later tonight Bob Zimmerman.

So what do you do? So they spent a lot of time analyzing and they figured out what they can do is change the

directory of the spacecraft so they can take advantage of the spacecraft so that it can take advantage of the weaker

thrusters to do what needs to be done. It's speeded up by slingshot effect so

that it makes up for the weaker thrust and they've done that. The result however

means that this spacecraft won't arrive till Mercury a year late. It'll arrive in

November 26 and instead of 25, but it'll work and that's the important thing.

They will fly by the Earth later this week but fly very close to the Earth only about a hundred and miles above the surface that's

twenty two miles closer than originally planned and now give it extra gravitational

boost to make up for the weaker thrust.

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