Australian Sky & Telescope - April 2018

30 AUSTRALIAN SKY & TELESCOPE April 2018

BIG BILL: STEVE BENTON; ASTRONOMERS: NASA / BARREL / BRETT ANDERSON; LAUNCH: BARTH NETTERFIELD

flyingastronomyballoonsunderthemidnightSundoes

limitthewavelengthsaccessibletodetectors:Antarctic

flightsprimarilyhostmicrowave,far-infraredandparticle

detectors.) Flights from Kiruna, Sweden, for example, can

last at most six days before they land in the Canadian Arctic

Archipelago 2,500 kilometres away.

Forthelongestflights,welaunchfromAntarctica.During

theAntarcticsummer,high-altitudewindscreateavast

polar vortex above the continent, which carries the telescope

aroundandaroundlikeahorseonagiganticmerry-go-

round.Theseflightsusuallylastmorethantwoweeks.The

Super-TIGERexperimentsettherecordflighttimein2013

with 55 days afloat.

Ta k i n g c h a n c e s: B L A S T ’s s t o r y

Ballooningisnotwithoutitsrisks.Aswithspacetelescopes,

there’salwaysachancethatthetelescopemightnotfunction

afterlaunch,andevenifitdoes,ithastosurvivethe

harrowingordealoflanding.TheadventuresoftheBalloon-

borneLargeApertureSubmillimetreTelescopeshowboththe

advantagesandperilsofflyingfromaballoon.

BLAST was designed to detect infrared radiation from

glowingdustgrainsinthreedifferentfar-infraredbands

(centredat250,350and500microns).Wecanmapcold

dust using these colours, tracing stellar nurseries within

ourgalaxy.Imagingmoredistantgalaxiesatthesame

wavelengthsalsorevealslightfrombright,youngstarsthat

wasabsorbedbydustandthenre-emittedintheinfrared.

TheoriginalBLASTtelescopetookthreeflights:thefirstin

2003fromFortSumner,totestthetelescopesystems;afour-

dayscienceflightin2005fromKiruna,Sweden;andin2006

a12-dayflightfromMcMurdoStation,Antarctica.BLAST

mapped star formation in the Milky Way and nearby galaxies,

as well as faraway galaxies in the adolescent universe. The

observationswentforwardnearlyperfectly—butthe2006

outingturnedouttobethetelescope’slast.

Onceaballoonisfinishedcollectingdataandreadyto

descend,NASAsendsaradiosignalthatseverstheconnection

SPREPPING FOR FLIGHTLeft:TheSuperBalloon-borneImagingTelescope(SuperBIT)payloadhangsfromalaunchvehicledubbedBigBill,

waitingforwindstodiedownenoughforlaunch.Right:Members of the Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL)

experimentjumpupanddowninwhattheycallthe‘lowwinddance’astheyhopeforthewindconditionsneededtolaunchtheirballoon.

GO FOR LAUNCH Just before BLAST’s first flight over Antarctica, the balloon and payload are readied for launch near McMurdo Station.

The 2,500-kilogram payload is at the right of this image, the red parachute is in the centre, and the partially inflated balloon is at the left.

BALLOON ASTRONOMY