720 XTF Search Results (expand=subject;f1-subject=Instrument;f2-associated-Lesson=X-Ray Science);f1-subject%3DInstrument;f2-associated-Lesson%3DX-Ray%20Science Results for your query: expand=subject;f1-subject=Instrument;f2-associated-Lesson=X-Ray Science Thu, 01 Jan 1970 12:00:00 GMT Kraushaar and Clark. Professors William Kraushaar and George Clark close the air-tight cover on the balloon gondola that carried the second of their two (unsuccessful) balloon experiments in search for high-energy cosmic gamma rays. Thu, 01 Jan 1970 12:00:00 GMT AXAF. Renamed the Chandra X-ray Observatory after launch, this image shows the instruments onboard the observatory. Thu, 01 Jan 1970 12:00:00 GMT