For decades, NASA has released enormous scientific balloons into Earth’s atmosphere, miles above the altitude of commercial flights. The balloon program is currently preparing new missions bearing sensitive instruments, including one designed to investigate the birth of our universe and another with ballooning origins that will fly on the International Space Station.
NASA’s Primordial Inflation Polarization Explorer (PIPER), will launch a series of test flights over the next few years that could confirm the theory that our nascent universe expanded by a trillion trillion (1,024) times immediately following the big bang. The rapid inflation would have shaken the fabric of space-time, according to researchers, generating ripples called gravitational waves. These waves, in turn, should have produced detectable distortions in the cosmic microwave background (CMB), the earliest light in the universe lengthened into microwaves today by cosmic expansion. The patterns will appear in measurements of how the CMB light is organized, a property called polarization. Discovering twisting, pinwheel-like polarization patterns in the CMB will prove inflation occurred and take astrophysicists back to the brink of the big bang.
PIPER will map the entire sky at four different frequencies, differentiating between twisting patterns in the CMB (indicating primordial gravitational waves) and different polarization signals due to interstellar dust. To maintain sensitivity, the telescope will fly immersed in a bucket of liquid helium the size of a hot tub. The PIPER mission was designed, built and tested at NASA’s Goddard Space Flight Center in collaboration with Johns Hopkins University in Baltimore, the University of British Columbia, Canada, the US National Institute of Standards and Technology and Cardiff University in Wales.
“We’re hoping to gain insight into our early universe as it expanded from subatomic size to larger than a planet in less than a second,” says Goddard’s Al Kogut, PIPER’s principal investigator. “Understanding inflation also augments our knowledge of high-energy particle physics, where the forces of nature act indistinguishably from one another.”
While PIPER prepares to observe roughly 20 miles above Earth, the latest iteration of the Cosmic Ray Energetics and Mass (CREAM) experiment is scheduled to launch to the International Space Station in August. Although CREAM was balloon-borne during its seven prior missions, the new payload will take the technology past Earth’s atmosphere and into space. Called ISS-CREAM, the experiment will directly sample fast-moving matter from outside the solar system, called cosmic rays, from its new vantage point on the Japanese Experiment Module Exposed Facility.
Cosmic rays are high-energy particles traveling at near the speed of light that constantly shower Earth. But precisely how they originate and accelerate through space requires more study, as does their abrupt decline at energies higher than 1,000 trillion electron volts. These particles have been boosted to more than 100 times the energy achievable by the world’s most powerful particle accelerator, the Large Hadron Collider at CERN.
ISS-CREAM is about the size of a refrigerator. It will carry refurbished versions of the silicon charge detectors and ionization calorimeter from the previous balloon missions over Antarctica. ISS-CREAM will contain two new instruments: the top/bottom counting detectors, contributed by Kyungpook National University in Daegu, South Korea, and a boronated scintillator detector to distinguish electrons from protons, constructed by a team from Goddard, Pennsylvania State University and Northern Kentucky University.
The international collaboration, led by physicist Eun-Suk Seo at the University of Maryland, includes teams from numerous institutions in the United States as well as collaborating institutions in the Republic of Korea, Mexico and France. Overall management and integration of the experiment was led by NASA’s Wallops Flight Facility under the direction of Linda Thompson, the CREAM project manager.
According to co-investigator Jason Link, a University of Maryland research scientist working at Goddard, the evolution of the CREAM project demonstrates the power of NASA’s Balloon Program as a developmental test bed for space instrumentation.“A balloon mission can go from an idea in a scientist’s head to a flying payload in about five years,” Link said. “In fact, many scientists who design experiments for space missions get their start in ballooning. It’s a powerful training ground for researchers and engineers.”
As is true with any complex mission, things don’t always go as planned. Such was the case for the Balloon Experimental Twin Telescope for Infrared Interferometer (BETTII) experiment, intended to investigate cold objects emitting light in the far-infrared region of the electromagnetic spectrum. BETTII launched on June 8 from NASA’s Columbia Scientific Balloon Facility in Palestine TX. Although nearly all the mission components functioned as they should, the payload detached from its parachute and fell 130,000 feet in 12 minutes as the flight ended the following day.
BETTII Principal Investigator Stephen Rinehart at Goddard estimates it will take several years to secure funding and rebuild the mission. Designed, assembled and tested at Goddard in collaboration with the University of Maryland, Johns Hopkins University, Cardiff University, University College London and the Far-Infrared Interferometric Telescope Experiment team in Japan, BETTII is designed to examine lower infrared frequencies with unprecedented resolution. While optical telescopes like Hubble cannot see stars shrouded by thick dust clouds, far-infrared observations pierce the veil, revealing how these objects form and evolve.
“BETTII is one of the more complex balloon experiments ever flown,” Rinehart says. “As a research community, we understand that this risk is necessary for the scientific and technical progress we make with balloons.”