brazing, metal melting; crystal growth; water / fluid dynamics Student research – 19 different student proposals. Several experiments were commended by the crew, including a dexterity experiment and a test of web-spinning by spiders in low gravity. Other – human adaptability, ability to work, dexterity; habitat design/operations. Because the solar scientific airlock – one of two research airlocks – was unexpectedly occupied by the "parasol" that replaced the missing meteorite shield, a few experiments were instead installed outside with the telescopes during spacewalks or shifted to the Earth-facing scientific airlock. Skylab 2 spent less time than planned on most experiments due to station repairs. On the other hand, Skylab 3 and Skylab 4 far exceeded the initial experiment plans, once the crews adjusted to the environment and established comfortable working relationships with ground control. The figure (below) lists an overview of most major experiments. Skylab 4 carried out several more experiments, such as to observe Comet Kohoutek. Nobel Prize Riccardo Giacconi shared the 2002 Nobel Prize in Physics for his study of X-ray astronomy, including the study of emissions from the Sun onboard Skylab, contributing to the birth of X-ray astronomy. Example Film vaults and window radiation shield Skylab had certain features to protect vulnerable technology from radiation. The window was vulnerable to darkening, and this darkening could affect experiment S190. As a result, a light shield that could be open or shut was designed and installed on Skylab. To protect a wide variety of films, used for a variety of experiments and for astronaut photography, there were five film vaults. There were four smaller film vaults in the Multiple Docking Adapter, mainly because the structure could not carry enough weight for a single larger film vault. The orbital workshop could handle a single larger safe, which is also more efficient for shielding. The large vault in the orbital workshop had an empty mass of 2398 lb (1088 kg). The four smaller vaults had combined mass of 1,545 lb. The primary construction material of all five safes was aluminum. When Skylab re-entered there was one 180 lb chunk of aluminum found that was thought to be a door to one of the film vaults. The big film vault was one of the heaviest single pieces of Skylab to re-enter Earth's atmosphere. A later example of a radiation vault is the Juno Radiation Vault for the Juno Jupiter orbiter, launched in