Pete Conrad and Alan Bean had just completed their first moonwalk 50 years ago this week. The Apollo 12 astronauts were the second crew to land on the Moon. And during four hours on the surface, they’d set up scientific instruments and gathered rocks and dirt.

Most of the samples were stored in bags. But the astronauts tracked a lot of dust into their Lunar Module, Intrepid, as Conrad told Mission Control:

CONRAD: Man, oh man, is it filthy in here. We must have 20 pounds of dust, dirt, and all kinds of junk. Al and I look like a couple of bituminous coal miners right at the moment. But we’re happy.

The engineers who are planning future lunar missions aren’t happy about the mess. Many of the Moon’s dust grains are jagged. That makes them cling to just about everything. They could easily damage important systems. And they could stick in astronauts’ lungs, perhaps causing health problems.

So future moonwalkers may need help keeping the dust outside. They might wear spacesuits that could dock to the outside of their landers, for example. The astronauts would crawl in and out through the back of the suits, without having to bring them indoors.

Whatever the solution, lunar explorers will need to keep clean — and not look like coal miners.

More about Apollo 12 tomorrow.

In the meantime, look for the Moon high in the sky at first light tomorrow. Regulus, the star that marks the heart of the lion, will stand to the lower left of the Moon.

Script by Damond Benningfield