Wood is good for certain niche space exploration applications, but the one below is not for spaceflight. According to the documentation for the archived photo:
Several spacecraft were built for the Mariner Mars 1964 mission. The ones that were actually launched were referred to as Mariner C-2 and Mariner C-3 until they were renamed Mariner 3 and Mariner 4, respectively. There was also a Proof Test Model (PTM, or Mariner C-1) and a Structural Test Model (STM). This photo shows Mariner C-2 configured for system tests in May 1964. It appears to be in the Spacecraft Assembly Facility, with the observation area at the top of the photo.
Documentation found in the Archives does not identify the purpose of the sphere covering the magnetometer during this test.
What is it for?
Why is it thick, heavy wood?
I can speculate - non magnetic materials near magnetometers, but a plexiglass or fiberglass box could have been used, both of those were already around at the time. For that matter, what about aluminum?
- Is it really hanging off of Mariner 3's magnetometer boom?
This wooden shell looks so heavy (it's not Balsa this time)!
above: Detail cropped from Photograph Number 293-6619Ac. Image credit: NASA/JPL-Caltech.
above: Photograph Number 293-6619Ac. Image credit: NASA/JPL-Caltech.