Balloon gondola prior to flight. The gondola holds three scientific instruments: the JPL-MkIV infrared spectrometer, the JPL-in situ ozone photometer, and a ultra-violet spectrometer built by the Atmospheric Environment Service of Canada. The weight of the gondola and instruments is 1700 lbs. The high-tech, cardboard "crash pads" used to cushion the landing are visible on the bottom corners of the payload.  Ballast, used to adjust rates of descent and/or to keep the payload at constant float altitude, is contained in the device hanging bottom center from the payload.

Photograph Taken By: Geoff Toon

Inflation of the balloon. A lot of helium is needed to deliver the 1700 lb payload to an altitude of 90,000 ft. Although the helium bubble looks modestly sized at the ground, it expands to a sphere about 300 ft diameter (e.g, the size of a football field) in the sparse air of the stratosphere. The "reconnaissance plane" used to terminate the balloon flight is visible in the foreground.

Photograph Taken By: Ross J. Salawitch

A moment before release. Proper layout direction of the helium bubble is critical for successful launch, so that prevailing winds will carry the bubble over the crane. The few seconds between untethering of the bubble and the release of the payload from the came are extremely tense.  Meteorologists on the NSBF staff determine the layout direction and whether local weather conditions are safe for launch.

Photograph Taken By: Phil DeCola

Into the clouds. The OMS payload begins its ascent, through low lying clouds. This picture was taken about 30 to 60 seconds after  release.  This is an unusual picture, as most launches occur on clear days.  The parachute that will deploy on descent is visible between the payload and the helium bubble.

 

Photograph Taken By: Ross J. Salawitch

In the trailer. Scientists monitor the progress of the flight, and control their  instruments, via radio links. From right to left, Jean-Francois Blavier, Geoffrey C. Toon, and Bhaswar Sen of JPL at the controls of the MkIV Fourier Transform Infrared Spectrometer.

 

Photograph Taken By: Ross J. Salawitch

Ozone monitor. The display shows the concentration of ozone (blue) and temperature (yellow) versus altitude. A characteristic temperature inversion (e.g., increasing temperature with rising altitude) is visible at the bottom of the stratosphere, precisely where the concentration of ozone begins to rise. This temperature inversion keeps stratospheric air isolated, or "stratified", from lower lying tropospheric air. These measurements were acquired during ascent by the JPL in situ ozone photometer and transmitted to the ground during flight (this photograph was taken while the balloon was at its "float altitude").

Photograph Taken By: Ross J. Salawitch

Balloon at night. The high altitude balloon has an eerie appearance at midnight over Fairbanks. At mid-latitudes, the curvature of the Earth leads to a few minute time difference between sunset at the ground and sunset at 90,000 ft. At high latitudes during summer, the sun shines directly on objects at 90,000 ft throughout the night because the Sun only drops a few degrees below the horizon (in other words, the balloon is high enough to "see the Sun" over the curvature of the Earth). The balloon was clearly visible to the naked eye, as an object larger than a planet but smaller than the  moon. This photograph was taken using a 200 mm lens and is comparable to the view from high-powered binoculars. Despite a lot of publicity prior to the balloon flight, the Fairbanks police received a number of calls reporting UFO sightings.

Photograph Taken By: Ross J. Salawitch

Termination. The balloon flight is terminated once scientific data have been obtained, or if the payload drifts towards either populated regions, large bodies of water, or in this case a mountain range. Although electronic means are used to track the payload, a reconnaissance plane is used for visual confirmation of the location. The flight is terminated by a command that initiates a small detonation, causing a cord to rip the mylar skin of the balloon. This rare photograph , taken from the airplane at about 15,000 ft altitude, shows the balloon just after the termination command was issued. The helium leaks out of the balloon rather slowly because the surrounding stratospheric air is at low pressure, about a factor of 50 less than the pressure at the ground (e.g., the surrounding air is doing little to "push" the helium out of the balloon).

Photograph Taken By: Dean Peterson

Click here to see our back up plan for bringing the balloon back to ground.

Initial descent. During initial descent, the parachute provides little resistance because the air pressure is too sparse. The descent rate is monitored closely by NSBF personnel. The mood is extremely tense during this stage of descent. Everyone awaits successful deployment of the parachute, which is revealed by a rapid drop in the fall rate once the balloon enters the lower atmosphere. This photograph shows the parachute before it has encountered sufficient air pressure to provide resistance to the fall.
Photograph Taken By: Dean Peterson

Chute is open. A great sigh of relief occurrs when the parachute is known to have opened, as revealed to personnel on the ground by a sharp drop in the payload's rate of fall. The pilot and passenger of the reconnaissance plane had this view of the parachute as the payload descended through Earth's middle troposphere (about 20,000 ft altitude).

 

Photograph Taken By: Dean Peterson

Almost down. The final phase of descent, showing the parachute and payload against the backdrop of the Alaskan Brooks Range mountains.  This particular flight was terminated a few minutes before final scientific data acquisition because the payload was approaching this mountain range, which would have complicated payload recovery.

 

Photograph Taken By: Dean Peterson

Landing zone. The reconnaissance plane watches the payload until it hits ground, assuring successful completion of the flight and noting surrounding landmarks for a helicopter that will ferry the payload, parachute, and balloon skin back to base. Note how close the payload landed to a nearby pond, which would have greatly complicated the recovery. The lush forest is typical of Alaskan summer, characterized by long periods of daylight, intermittent rain, and, for the summer of 1997, extremely warm conditions (highs in the mid-90s). There are many lakes in Alaska, so obtaining a "dry landing" is somewhat a matter of chance.

Photograph Taken By: Dean Peterson

Upright, intact, and dry. The gondola has landed upright, intact, and dry! Note the cardboard "crash pads" that have worked flawlessly to cushion the final impact. The gondola was returned to Ft. Wainwright Army Base by helicopter, and eventually to JPL via truck. The closed "window" on the gondola had been open during flight, one of several ports used to acquire scientific data. Subsequent examination of the payload showed no damage from impact. The parachute will be repacked and reused.

Photograph Taken By: Geoff Toon