Canceled Apollo missions planning their own circumlunar flight for December to upstage the Americans once again (see Zond program). McDivitt's crew—who had grown accustomed to working with LM-3 and preparing for its flight—was kept on the D mission which now became Apollo 9, while Borman's crew would fly the CSM lunar orbit mission on Apollo 8, and the E mission was canceled. The swap of crews was also decisive in who would be the first man to walk on the Moon. Pete Conrad was backup Commander for McDivitt's crew, and by the process of crew rotation, would have been in line for Commander
Silly Putty lint, pet hair, or ink from various surfaces. The material's unique properties have found niche use in medical and scientific applications. Physical therapists use it for rehabilitative therapy of hand injuries. A number of other brands (such as "Power Putty" and "TheraPutty") alter the material's properties, offering different levels of resistance. The material is also used as a tool to help reduce stress, and exists in various viscosities based on the user's preference. Because of its adhesive characteristics, it was used by Apollo astronauts to secure their tools in zero-gravity. Scale model building hobbyists use the putty as a masking