There were seven independent camera systems, each housed in its own pressure
vessel. Two sets of three cameras were affixed to the outer frame of the gondola to
the left and to the right of the lidar package. The seventh camera, the one with the
narrow field of view, was as near as possible to the center of the gondola. The
liquid cooling system was primarily for cooling the laser head and its electronics.
At float, glycol would be pumped through the radiator to radiate away the waste
heat to space. The lidar telescope occupied the central spot in the gondola, next to
the lidar pressure vessel. Because the field of view of the telescope was rather
small (approximately 0.2 mrad), the telescope needed to be firmly attached to the
lidar pressure vessel to minimize the chance for misalignment during the balloon
flight. There were four 28 volt rechargeable lithium batteries to supply power to
the experiments during launch preparation and ascent when the solar array would
not be facing towards the Sun. On reaching 27 km (90,000 ft), the NASA rotator
would point the solar array towards the Sun for maximum power generation. The
optical experiments (cameras and lidar) remained in the shadow produced by the
solar array. The orientation was key, because all the waste heat generated by the
lidar had to be dumped to space, and the radiator only worked properly if it was
facing away from the Sun.
The suspension system that connected the gondola to the rotator also served as
a mount for the antenna boom. All communication antennae, including the NASA
TDRSS high gain antenna, TDRSS omni directional antenna, Iridium Pilot, GPS
and GPS compass, were mounted on the 6.7 m (22 ft) long antenna boom on top
of the box beam. As this was the highest point of the gondola, it allowed almost
unobstructed line of sight communications with satellites. The flight computer
sent a telemetry frame over the satellite links every 2 seconds containing critical
information on all subsystems such as the temperatures, voltages and currents of
the different power buses, timestamps, and information on whether a system was
on or off, as well as the configuration of the system. All science data was stored
onboard because the bandwidth of the satellite links was inadequate to transmit it
continuously. The support instrument package (SIP) containing the NASA flight
computers and communication electronics was bolted below the gondola.
Flight 684N achieved a float altitude of 39 km (127,000 ft) and traveled west to
Canada, where it was terminated on July 14. After a flight of 5 days 18 hours, it
landed safely near Bathurst Inlet, some 300 nmi north-northeast of Yellowknife.
7.2 EARTH STUDIES
7.2.1 Magnetometry
The mathematical description of the Earth’s magnetic field, and the manner in
which it varies, is usually performed using the mean of stable observatories. To
increase the coverage, measurements are performed every 5 years using mobile
instruments. There are large uncovered surfaces (oceans, polar areas) in which
150 Scientific Flight Types
vessel. Two sets of three cameras were affixed to the outer frame of the gondola to
the left and to the right of the lidar package. The seventh camera, the one with the
narrow field of view, was as near as possible to the center of the gondola. The
liquid cooling system was primarily for cooling the laser head and its electronics.
At float, glycol would be pumped through the radiator to radiate away the waste
heat to space. The lidar telescope occupied the central spot in the gondola, next to
the lidar pressure vessel. Because the field of view of the telescope was rather
small (approximately 0.2 mrad), the telescope needed to be firmly attached to the
lidar pressure vessel to minimize the chance for misalignment during the balloon
flight. There were four 28 volt rechargeable lithium batteries to supply power to
the experiments during launch preparation and ascent when the solar array would
not be facing towards the Sun. On reaching 27 km (90,000 ft), the NASA rotator
would point the solar array towards the Sun for maximum power generation. The
optical experiments (cameras and lidar) remained in the shadow produced by the
solar array. The orientation was key, because all the waste heat generated by the
lidar had to be dumped to space, and the radiator only worked properly if it was
facing away from the Sun.
The suspension system that connected the gondola to the rotator also served as
a mount for the antenna boom. All communication antennae, including the NASA
TDRSS high gain antenna, TDRSS omni directional antenna, Iridium Pilot, GPS
and GPS compass, were mounted on the 6.7 m (22 ft) long antenna boom on top
of the box beam. As this was the highest point of the gondola, it allowed almost
unobstructed line of sight communications with satellites. The flight computer
sent a telemetry frame over the satellite links every 2 seconds containing critical
information on all subsystems such as the temperatures, voltages and currents of
the different power buses, timestamps, and information on whether a system was
on or off, as well as the configuration of the system. All science data was stored
onboard because the bandwidth of the satellite links was inadequate to transmit it
continuously. The support instrument package (SIP) containing the NASA flight
computers and communication electronics was bolted below the gondola.
Flight 684N achieved a float altitude of 39 km (127,000 ft) and traveled west to
Canada, where it was terminated on July 14. After a flight of 5 days 18 hours, it
landed safely near Bathurst Inlet, some 300 nmi north-northeast of Yellowknife.
7.2 EARTH STUDIES
7.2.1 Magnetometry
The mathematical description of the Earth’s magnetic field, and the manner in
which it varies, is usually performed using the mean of stable observatories. To
increase the coverage, measurements are performed every 5 years using mobile
instruments. There are large uncovered surfaces (oceans, polar areas) in which
150 Scientific Flight Types