Description of the payload

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne mission to measure the polarization of the cosmic microwave background (CMB) in search of the signature of primordial gravity waves excited by an inflationary epoch in the early universe.

It is composed by two identical telescopes cooled to 1.5 K within a large (3 meter tall, 3500-liter capacity) liquid helium bucket dewar. There are no windows between the LHe-cooled telescope and the ambient environment: PIPER uses the efflux of boiloff helium gas to prevent the atmosphere at balloon altitudes from condensing on the optics. This technique was first applied in a previous balloon-borne instrument denominated ARCADE. The unusual cryogenic design provides mapping speed a factor of 10 better than any other CMB instrument, allowing PIPER to achieve sensitivities with overnight balloon flights that would otherwise require 10-day flights from other places like Antarctica.

Each of PIPER's twin telescopes illuminates a pair of 32x40 element transition-edge superconducting detector arrays for a total of 5120 detectors. A Variable-Delay Polarization Modulator (VPM) injects a time-dependent phase delay between orthogonal linear polarizations to cleanly separate polarized from unpolarized radiation. The combination of background-limited detectors with fast polarization modulation allows PIPER to rapidly scan large areas of the sky.

Details of the balloon flight and scientific outcome

 

Launch site: Scientific Flight Balloon Facility, Fort Sumner, (NM), US  
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Raven - 11.820.000 cuft
Flight identification number: 681N

The balloon was launched at 16:12 utc on October 13th, 2017 using the dynamic method, assisted by the Big Bill launch vehicle. Climb to altitude was nominal and ceiling of 98.000 ft was reached about 19:30 utc while flying E of Tucumcari, new Mexico. The balloon moved during the entire flight in a NE direction more or less along along the New Mexico / Texas border, as can be seen in the map at left.

The flight was terminated and the payload separated from the balloon at 3:00 utc on October 14th, while flying over Union County in NE New Mexico. The landing of the payload was a little rough as it toched ground with a sideways speed around 40 miles/hour and did a cartwheel, landing on the bottom, then on the top, and then on the bottom again. However, the instrument resisted very well the ride and emerged in good shape at all.

Total flight time from launch to landing was 11 hours and 30 minutes.

External references and bibliographical sources

Images of the mission