Balloons Over Chicagoland

Inflated balloon lifting the payload nicknamed Defiance used in Adler Planetarium’s NITELITE a people-powered science mission, just prior to launch. Several nights this Spring a team from the Adler Planetarium launched balloons into the night sky. Altho not specifically in celebration, cheers resounded as the balloon reached altitude and hundreds of images of the nighttime landscape below were captured. Each flight contributed immediately useful information that was then applied to the next flight, culminating in a seriously successful flight the night of April 29th over Kankakee and the surrounding area. Designed to measure the nature and intensity of artificial light spilling upwards into the night sky, these flights are part of the on-going NITESat project, part of the larger twelve-year old Far Horizons Program. Ken Walczak, project manager, and Geza Gyuk head up the team, which includes an ever-changing, enthusiastic group of interns and volunteers.

That’s one festive balloon! Go Defiance!

To clarify… is the name of the eventual NITELITE is the name of the stratospheric High Altitude Balloon (HAB) mission version of NITESat Every good project needs a succinct name, hopefully an acronym. NITESat, Night Imaging and Tracking Experiment Satellite, is the cubesat mission Adler has planned to image light pollution from orbit. Great name. This project, using balloons for the same purpose, is called NITELITE. Great name, and fitting for it’s smaller scale. These balloons carry several downward-pointing cameras designed to measure the amount of energy which is lost to the night sky rather illuminating the intended roads, sidewalks and other areas for human travelers on the ground. This lost energy is a waste of resources that also causes harm to humans and migrating birds, among other negative side effects. Hey, who needs a street light shining into your bedroom at night when you are trying to sleep, instead of towards the street below? These first flights allowed the team to fine-tune their cameras’ aperture size, length of exposure, and frequency of image capture. Three cameras capture slightly differing views of the landscape. One points directly downward, truly a nadir view, while the other cameras flank this central lens, collecting images at an oblique angle of about 20 degrees. A series of subsequent flights are scheduled in this ongoing project.

Pre-flight computer check by students and volunteers David Hurst, Jeff Wiedemann, Eleanor Marshall, Jeremy Seeman and Paulina Kawalec at Koerner Aviation’s hangar in Kankakee.

After capturing the imagery, the individual images are sorted to select the best shots in the sequence – there is much intended redundancy. Remember the balloon is propelled by our variable winds, moving at irregular

speeds while performing slow pirouettes as it travels across the night sky. Not every image will be of usable quality. The selected images are “stitched” together to form a mosaic of the landscape over which the balloon flew. Images must then be registered to the actual ground. While the cameras geotag the images when captured, the precision of this step is not sufficient to really lockdown the nighttime balloon imagery over another set of imagery captured during the day - the aerials typically seen on Internet mapping sites. Those road intersections and building corners are kinda hard to make out in night-captured imagery.

Knowing exactly where each light source is located on real ground allows the team to delve into the particulars of the lamp, answering questions important to their research such as: sodium or mercury vapor, or LED? How many lumens or kelvins are output, as measured from above? This location-refining task is perfect for citizen scientist participation, including STEM students. Just as launch prep and deployment relies on a cadre of volunteers, post-flight processing provides opportunities for volunteers to join in the fun. Using web platforms and freeware such as Zooniverse to organize the task at no or minimal cost to the citizen scientist, Walczak and Gyuk invite crowd-sourcing to complete that task. Contact the Adler Planetarium team to participate. Ken Walczak, project manager, ksalczak@adlerplanetarium.org Geza Gyuk ggyuk@adlerplanetarium.org Watch this space for news of the next flights. -Mary Elliot (edited by mwilliamson)

Sample of the flight captured imagery

Arrangement of the three cameras used in NITELITE missions.