Where balloons have made advances

摘要

In 1998, a project called Balloon Observations of Millimetric Extragalactic Radiation and Geophysics (BOOMERanG)madea fine-scale map of the cosmic microwave background over a part of the sky and provided evidence for its 'flatness'. A follow-up flight in 2003 was able to detect some polarization in the background - consistent with a period of 'inflation' in the very early cosmos. The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) made nine 1-day flights in 1993-2002 and detected more than 2,400 antiprotons, thus contributing 80% of the records of incoming antimatter. More recent longer flights revealed constraints on the presence of anti-helium. The instruments rival the sensitivity of the $1.5-billion Alpha Magnetic Spectrometer - still awaiting a ride to the International Space Station.