TopHat

TopHat was not a fixed observatory but a balloon-borne scientific experiment launched from McMurdo Station, Antarctica, to study the cosmic microwave background — the faint afterglow of the Big Bang.

About TopHat

Also known as part of the "Submillimeter Astrophysics Experiment," TopHat was built for Dr. Edward Cheng of NASA's Goddard Space Flight Center, in association with the University of Chicago, the University of Wisconsin–Madison, and the Danish Space Research Institute. It took roughly six years to build and deploy, and was designed as a follow-up to the earlier BOOMERanG experiment.

History

TopHat launched on January 2, 2001, and flew for 644 hours over Antarctica before landing on January 31, 2001. Its working payload operated until January 10, 2001, when the liquid cryogens cooling its detectors ran out; the balloon then continued circling the continent until conditions allowed a safe landing, ultimately touching down about half a mile from its targeted ice shelf. The data-recording discs were recovered safely, though the gondola itself had not been recovered as of August 2001.

Telescopes & research

TopHat's design was unique: the telescope sat atop the balloon itself, rotating at a constant rate around a vertical axis to scan a 48-degree-diameter window of sky with no obstructions. Flying 38 kilometres above the ground on a balloon spanning 29.5 million cubic feet, it aimed to measure the tiny temperature variations in the cosmic microwave background — radiation dating to roughly 300,000 years after the Big Bang — to help determine how much matter fills the universe, how it is distributed, how the universe expands, and whether its geometry is flat, building on results from BOOMERanG.

Location & getting there

TopHat operated over Antarctica, launched from McMurdo Station at roughly -85.15°S, -164.44°W. As a one-time balloon flight rather than a ground-based facility, it has no public visiting site today.

See your named star from here

TopHat's mission was to map the oldest light in the universe rather than individual stars, but the same principle of aiming an instrument at precise sky coordinates applies to any named star viewed from Earth today. Explore our star-naming packages or browse the star catalogue to find yours.