comparable to 3G systems. For balloon-to-balloon and balloon-to-ground communications, the balloons use antennas equipped with specialized radio frequency technology.
Termination
One of the most important aspects of balloon command and control is related to
the decision to terminate a mission. This could be at the end of the mission in a
planned area or during an abnormal situation where the balloon has a leak and is
losing altitude. The choice facing the ground crew is where and how to terminate
the flight to optimize the recovery of the payload and to minimize any damage to
life and property. This also relates to potential issues with ocean landings, where
there is a requirement to enable the payload and the balloon to sink to minimize
the risk to marine life. The balloon and payload may be a thousand miles from a
ground based command site and therefore termination must be commanded from
an aircraft or a satellite. In that case, the payload remains attached to the balloon
in order to allow its weight to sink them both.
In most cases, after the science measurements are completed, flight controllers
send a radio command that separates the payload from the balloon. The payload
descends to the ground on a parachute where it can be retrieved and flown again.
Payload separation opens a large tear in the balloon fabric, and this releases any
remaining helium. On reaching the ground the balloon is retrieved and, being of
no further use, is discarded.
If all goes according to plan, the flight can be concluded at a predetermined time
and the aircrew receives clearance from the FAA either to terminate the flight or to
separate the payload from the balloon. After surveying the projected landing point,
a telemetry command fires an explosive squib that separates the parachute from the
balloon at about 120,000 feet. This separation tears the balloon, and the payload
parachutes down in about 50 minutes. The circling aircraft monitors the descent of
both items. As the payload touches the ground a sensor sends a signal which leads
to the next step of firing explosives that separate the parachute from the payload, to
prevent the chute dragging the payload in strong wind situations. The recovered
payload is returned to the science team for refurbishment to fly another day.
4.2.6 Recovery Operations
In theory, the ideal recovery is one where the payload lands where you intended it,
intact and undamaged, so that the instruments can be reused. Ideally, this is a place
with easy access and has no hazards associated with the payload or landing area.
To the contrary the worst recovery situation is a crash with total loss of the payload. Even worse is total loss of the payload at sea. One payload is known to have
hit a house. Fortunately no one was injured, and damages were paid to the owner.
In between these extremes lies a range of recovery situations.
76 Mission Drivers and Operations
Termination
One of the most important aspects of balloon command and control is related to
the decision to terminate a mission. This could be at the end of the mission in a
planned area or during an abnormal situation where the balloon has a leak and is
losing altitude. The choice facing the ground crew is where and how to terminate
the flight to optimize the recovery of the payload and to minimize any damage to
life and property. This also relates to potential issues with ocean landings, where
there is a requirement to enable the payload and the balloon to sink to minimize
the risk to marine life. The balloon and payload may be a thousand miles from a
ground based command site and therefore termination must be commanded from
an aircraft or a satellite. In that case, the payload remains attached to the balloon
in order to allow its weight to sink them both.
In most cases, after the science measurements are completed, flight controllers
send a radio command that separates the payload from the balloon. The payload
descends to the ground on a parachute where it can be retrieved and flown again.
Payload separation opens a large tear in the balloon fabric, and this releases any
remaining helium. On reaching the ground the balloon is retrieved and, being of
no further use, is discarded.
If all goes according to plan, the flight can be concluded at a predetermined time
and the aircrew receives clearance from the FAA either to terminate the flight or to
separate the payload from the balloon. After surveying the projected landing point,
a telemetry command fires an explosive squib that separates the parachute from the
balloon at about 120,000 feet. This separation tears the balloon, and the payload
parachutes down in about 50 minutes. The circling aircraft monitors the descent of
both items. As the payload touches the ground a sensor sends a signal which leads
to the next step of firing explosives that separate the parachute from the payload, to
prevent the chute dragging the payload in strong wind situations. The recovered
payload is returned to the science team for refurbishment to fly another day.
4.2.6 Recovery Operations
In theory, the ideal recovery is one where the payload lands where you intended it,
intact and undamaged, so that the instruments can be reused. Ideally, this is a place
with easy access and has no hazards associated with the payload or landing area.
To the contrary the worst recovery situation is a crash with total loss of the payload. Even worse is total loss of the payload at sea. One payload is known to have
hit a house. Fortunately no one was injured, and damages were paid to the owner.
In between these extremes lies a range of recovery situations.
76 Mission Drivers and Operations