A NASA telescope is barely clinging to space after a failed rescue effort left it tottering lower and lower. The U.S. Space Force predicts the Swift Observatory will come crashing down on or around Friday. Most of the 1 1/2-ton telescope is expected to burn up in the atmosphere. But NASA says a handful of pieces could survive reentry. Swift observed some of the universe’s biggest explosions during its 22 years in orbit. Intense solar activity dragged it down faster than expected, prompting NASA to stage a rescue mission. But the robot could not reach the telescope and plunged back to Earth in September.