Aerostats, commonly known as airships or blimps, are tethered or moored lighter-than-air aircrafts that obtain their buoyancy from contained lifting gases less dense than the surrounding air. Unlike free balloons, aerostats are steerable and have propulsion systems that allow controlled flight. Modern aerostats can stay aloft from several days to months depending on their size and payload. They are being used for various commercial, scientific and military applications that require persistent presence in the air without the need for runways.
Aerostat Technology
Aerostats System employ helium or hydrogen as the lifting gas to achieve buoyancy. The outer covering material of the aerostat is generally made from durable, multi-layered synthetic fabrics like polyester or polyurethane coated with reflective metallic surfaces to provide strength as well as reflect sunlight. The gas containment system utilizes a series of valves, sensors and seals to carefully manage the relative quantities of lifting gas and air inside the aerostat. To counteract the effects of changing weather conditions, modern aerostats are equipped with automatic pressurization and venting systems.
Payload accommodation inside the aerostat depends on its size but can range from 200 to 1000 pounds. The payloads are usually suspended below the aerostat hull through cables and electrical winches. Aerostats are powered by on-board combustion or electric engines and carried batteries that facilitate controlled ascent, descent andHorizontal maneuvers. Navigation and communications are handled through onboard avionics suites comprising of autopilots, navigation radars and satellite links. Aerostats can stay airborne for weeks or months depending on weather conditions and payload energy demands through floating power generation typically solar panels.
Military Applications of Aerostats
Militaries across the world have been leveraging aerostats for various roles such as aerial intelligence, surveillance and reconnaissance. Aerostats carrying day/night radars, cameras and signals intelligence payloads act as persistent eyes in the sky, providing situational awareness over large areas. Commonly used militar aerostat systems are Persistent Ground Surveillance System (PGSS) and Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System (JLENS). They offer unparalleled endurance of months at strategic altitudes of 10,000-30,000 feet without needing logistical resupply.
Ongoing advances in sensor payloads include improved high definition cameras, hyperspectral and long range ground moving target indication radars. Aerostats also serve communication relays for frontline troops and as a means to intercept enemy communications and satellite signals. During war games and exercises, they help commanders to gain real-time understanding of battlefield situations. Due to their covert signatures and high vantage points, aerostats play a useful role in border and coastal monitoring against infiltration threats. Overall, they provide a cost effective alternative to space based, airborne and ground based persistent surveillance assets.
Weather Monitoring Using Aerostats
Aerostats have been an important tool for atmospheric research and weather monitoring for over a century. They help meteorologists to gather upper atmospheric data through insitu sensors via lightweight, low-cost platforms. High altitude aerostats equipped with radiosondes and dropsondes facilitate vertical profiling of meteorological parameters such as temperature, humidity, wind speed/direction up to the lower stratosphere. Their persistent presence complements infrequent weather balloons and infills sparse radiosonde data over remote oceans and land areas.
Today's scientific aerostats carry miniaturized instrument suites containing ozone monitors, hyperspectral infrared/visible cameras for cloud analysis as well energy balance sensors. This offers data to improve weather and climate modeling efforts. Aerostats serve as communications relays and launching platforms for additional UAVs during field campaigns, helping coordinate activities between flights. Overall, their ability to loiter steadily for extended periods through all weather assists researchers in better understanding atmospheric dynamics, precipitation processes, storm development and phenomena's like El Nino.
Disaster Monitoring and Support Missions
Aerostats have supported several disaster recovery, damage assessment and relief coordination missions. During flooding events caused by hurricanes, they provide emergency managers continual situational updates due to their ability to withstand extreme weather conditions. Aerostat mounted cameras help locate stranded citizens in need of rescue among inundated areas difficult to access by aircraft or vehicles. Similarly, during wildfires their infrared cameras assist firefighters to observe fire front spread and locate people trapped.
Aerostats are usually the first aerial asset deployed to transmit impact assessment pictures to relief teams after earthquakes and volcanic eruptions. Their telecommunications capabilities played a role in restoring communications in Haiti after the 2010 earthquake. Persistent monitoring by deployed aerostat networks proved useful during oil spill responses like Deepwater Horizon through aerial observations of slick movement and thickness. In future, longer endurance hybrid electric aerostats could potentially serve as communications relays/ISR nodes during large scale evacuations from affected regions. Overall, aerostats demonstrate their effectiveness for aiding emergency coordination, search and assessment purposes during natural and manmade catastrophes.
Commercial Applications of Aerostats
Besides scientific and military uses, aerostats also find commercial applications in communications, infrastructure monitoring, recreational tourism and agriculture. Communications aerostats serve as cost effective wireless coverage extenders, providing connectivity to remote communities through broadband internet links. Many cellular operators deploy aerostat mounted 3G/4G base stations to strengthen coverage in rural terrains. Transmission line and pipeline operators use aerostat optical cameras to inspect long infrastructure corridors for leakage/damage detection through aerial surveys.
Several tour operators across the world offer sightseeing trips using aerostats for panoramic views. They are popular tourist attractions during festivals and fairs, giving public aerial rides. Agricultural aerostats equipped with thermal/multispectral cameras assist farmers in monitoring crop health, detecting disease/pest infestations over wide areas. This helps optimize irrigation, fertilizing and apply pest controls on fields. Several vineyards are taking advantage of aerostats monitoring platforms to expand precision viticulture practices. Increasingly, private and public entities are recognizing the benefits of persistent aerostat based monitoring capabilities for various industrial, safety.
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