Rationality be damned! When it comes to space exploration, not even the world's most brilliant scientific minds are immune to superstitions. Take, for example, the superstition-turned-tradition of eating peanuts during space launches:
The tension was palpable in the control room at NASA’s Jet Propulsion Laboratory (JPL) in the minutes leading up to the Aug. 5 landing of the Mars rover Curiosity. Rows of headset-clad flight controllers in matching pale blue polo shirts huddled over their computers, awaiting the rover descent’s ”seven minutes of terror.” Then, seemingly from nowhere, bottles of peanuts started to appear, and soon all the engineers and scientists were munching on handfuls of the proteinaceous snack. [...]
The peanut tradition started in the 1960s during JPL’s Ranger missions, which were spacecraft designed to fly into the moon and take pictures of it. The first six Ranger spacecraft failed during launch or while leaving orbit, but on the 7th launch, someone brought peanuts into mission control, and the mission succeeded. It’s been a tradition at JPL launches and landings ever since.
Tanya Lewis of Wired Science lists more strange traditions of NASA and their Russian/Soviet counterparts - for example:
Before a launch, the commander must play cards (supposedly either Blackjack or 5-card poker) with the tech crew until he loses a hand. The tradition’s origins are a mystery, but it may have begun during the two-man Gemini missions.
After the shuttle orbiter was successfully transported from the Orbital Processing Facility to the Vehicle Assembly Building, the managers would provide the team with round donuts and bagels. It may have to do with the fact that these foods are round like the wheels of the shuttle transporter.
Russian Roscosmos/Soviet Space Agencies
Before leaving the Star City training complex near Moscow, Soyuz flight crews leave red carnations at the Memorial Wall in memory of first man in space, Yuri Gagarin, and four other cosmonauts. They visit Gagarin’s office, sign his guestbook, and supposedly ask his ghost for permission to fly.
On their way to the launch, Russian cosmonauts are known to urinate on the right rear wheel of their transfer bus, an act supposedly performed by Yuri Gagarin. Female cosmonauts are excused, but certain women have been known to carry vials of their urine to spill in solidarity.
Read more over at Wired Science: Link