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Ascending Horizons: The Evolution of Stratospheric Balloons and High-Altitude Surveillance”


Stratospheric balloons, often referred to as near-space balloons, have quietly been making strides in scientific research, meteorological observations, and military applications. These high-altitude balloons are designed to withstand the harsh conditions of the upper atmosphere and have proven to be valuable tools in a variety of fields. In this article, we delve into the world of stratospheric balloons, exploring their diverse applications, technological advancements, and their potential to transform the way we gather data and conduct military operations. Additionally, we will also discuss China’s contribution to high-altitude surveillance using stratospheric balloons.


Stratospheric Balloons in Scientific Research and Meteorological Observations:

Atmospheric balloons are balloons that are used for scientific research and meteorological observations. These balloons are typically large and made of materials that can withstand the high altitudes and extreme temperatures of the upper atmosphere.

Stratospheric balloons are high-altitude balloons that are released and operated into the stratosphere ( region of the atmosphere (15 to 45 km in altitude).

Reaching the Upper Atmosphere: These balloons can ascend to altitudes of up to 40 kilometers or more, depending on their size and design. This enables researchers to explore regions of the atmosphere that were previously challenging to access, providing valuable insights into Earth’s upper atmospheric layers. Stratospheric provides platform to test and advance space science for far less than the cost of a satellite (up to 40 times less).

Collecting Critical Data: Stratospheric balloons serve as versatile platforms for scientific instruments and equipment. They carry cameras, sensors, radiosondes, and other scientific payloads to high altitudes, where they can gather crucial data on weather patterns, atmospheric conditions, and various scientific phenomena.

Long-Duration Flights: Some stratospheric balloons can conduct extended flights, lasting for days, weeks, or even months. These prolonged missions are ideal for collecting continuous data and monitoring long-term changes in the atmosphere and environment.

The original stratospheric balloons were flown by NASA in the 1950s, and the agency still uses them for science missions. The Canadian Space Agency uses stratospheric balloons to test and validate new technologies developed for long-duration space missions and to perform scientific experiments in a near-space environment.

Challenges in Near-Space Operations

Operating in near space, located approximately 20 kilometers above sea level, presents a unique set of challenges that have limited its exploration and utilization until now. Often referred to as a “death zone” for drones, this region is characterized by thin air, where generating lift becomes a formidable task. Additionally, the extreme cold at these altitudes poses a significant threat to electronic components, particularly batteries, which are prone to failure in such frigid conditions.

The near-space realm has long held promise for intelligence services due to its strategic advantages, including the ability to conduct surveillance over vast areas. However, it has remained largely unexplored because it poses operational challenges that are distinct from those encountered by traditional aircraft and satellites. Until recently, the Northrop Grumman RQ-4 Global Hawk, with a limited altitude of approximately 19 kilometers, represented the highest-flying drone in active use.

Addressing the Challenges of High-Altitude Drones

Developing high-altitude drones capable of withstanding these harsh conditions remains a complex endeavor. Among the myriad challenges faced by engineers and scientists, one of the most significant is the near-vacuum environment, where electric currents can generate sparks that, in turn, lead to equipment shortages and damage. This presents a considerable hurdle in designing drones for near-space operations, making them inherently more challenging to construct compared to their lower-flying counterparts. The question of whether these high-altitude drones can play a practical role in military operations continues to be a subject of ongoing exploration.

One of the primary challenges faced in near space is the extreme temperature variation, with fluctuations of up to 150 degrees Celsius. Temperatures can plummet to as low as -90 degrees Celsius at altitudes of 35 kilometers (22 miles), posing additional difficulties for maintaining electronic components, particularly batteries, in operational condition.

Navigating the Complex Winds of the Stratosphere

Stratospheric winds are stratified, comprising layers that travel in varying directions and speeds. While one layer may push a balloon significantly off course, another adjacent layer might offer favorable winds that facilitate the desired direction of movement. Balloons, when subjected to these winds, can drift more than 200 kilometers (125 miles) from their release point.

Furthermore, as balloons ascend to higher altitudes, they undergo expansion, with their dimensions growing from 2 meters (6.5 feet) to as much as 8 meters (26 feet) across. This expansion occurs due to the decreasing air pressure as balloons climb higher in the atmosphere. Ultimately, balloons reach a point of rupture when exposed to air pressure only a small fraction of what is encountered at the Earth’s surface, leading to their eventual breakdown.

Currently, balloons are subject to the whims of the wind, limiting their ability to remain in a specific area for an extended period. To address this, Project Loon employs sophisticated software algorithms that guide balloons into wind layers moving in the desired direction. By harnessing the power of these winds, the balloons can be strategically arranged to form a cohesive communications network.

Unlocking the Potential of Near Space

Despite these obstacles, scientists are driven by the goal of creating durable near-space vehicles capable of conducting extended observations over large areas for weeks, months, or even years. Drones offer a cost-effective alternative to satellites, with the potential to fulfill similar mission objectives at a fraction of the cost. Depending on the mission’s requirements, these platforms must meet a wide range of performance criteria to ensure their effectiveness in the stratosphere.

Google Project Loon

Project Loon was an ambitious endeavor by Google’s sister company, Loon, to provide internet access to remote and underserved areas using stratospheric balloons. Launched in July 2020, it aimed to connect people in rural and isolated regions, fill coverage gaps, and offer connectivity in disaster-stricken areas. These stratospheric balloons, which floated at around 65,000 feet above the Earth’s surface, acted as airborne Wi-Fi providers.

Initially tested in Kenya, Project Loon’s early service quality testing showed promising results. Users experienced uplink speeds of 4.74 Mbps, downlink speeds of 18.9 Mbps, and impressively low latency of 19 milliseconds. This indicated that the technology was viable for various applications, including voice and video calls, streaming, messaging, email, and web browsing.

However, despite these positive developments, Project Loon faced challenges and was eventually closed down. One reason for its discontinuation was likely the high operational costs associated with maintaining and controlling a fleet of stratospheric balloons. Another factor might have been the rapid expansion of ground-based internet infrastructure and alternative connectivity solutions that made the project less economically viable.

Nonetheless, the successful deployment of stratospheric balloons for internet access demonstrated their potential for providing connectivity in remote and disaster-affected areas. Additionally, the technology’s reliability piqued the interest of the military, which saw opportunities for employing similar platforms, including balloons, aerostats, airships, satellites, and UAVs, for real-time intelligence, surveillance, and reconnaissance (ISR) purposes in battle spaces. While Project Loon itself may have come to an end, the legacy of its innovative approach to connectivity continues to influence similar initiatives and advancements in the field of stratospheric technology.

Looking Ahead: Leveraging Higher Altitudes

The quest to explore near space continues, with the aspiration of capitalizing on the broader range of winds available at higher altitudes. ALTA, a pioneering project, is set to operate even higher than Project Loon, ascending to altitudes of 75,000 to 90,000 feet (approximately 22,900 to 27,400 meters or 14 to 17 miles). In these less predictable wind conditions, success hinges on the balloon’s ability to precisely identify favorable wind patterns. While advancements in machine learning and data analysis are enhancing navigation, progress remains gradual. Theoretically, by adjusting altitude, it should be possible to locate winds blowing in any desired direction, opening up new frontiers for exploration and innovation in near-space operations.

Advancements in Stratospheric Balloon Technology

Stratospheric balloons have emerged as a versatile platform for various scientific research endeavors. Typically constructed from ultra-thin plastic and filled with helium, these balloons assume a colossal upside-down “teardrop” shape, often reaching heights comparable to the Eiffel Tower. Suspended along the flight chain of these balloons are multiple gondolas, each capable of carrying diverse payloads, including equipment for scientific research, astronomy, atmospheric chemistry, weather forecasting, and technological demonstrations. These payloads can collectively weigh up to 1.1 tons.

Some of these stratospheric balloons are substantial in size, surpassing the dimensions of a football field and possessing the capability to hoist payloads weighing up to 2 tonnes to altitudes as high as 40 kilometers. They can linger at altitudes of up to 42 kilometers, allowing their instrument packages to remain aloft for several hours or, in certain cases, for days, weeks, and even months. Notably, stratospheric balloons operate without the need for engines or fuel, relying solely on natural forces: buoyancy for lift, winds for direction, and gravity for descent.

Stratospheric Winds and Navigation

The stratosphere comprises multiple layers with distinct wind patterns blowing in varying directions and speeds. In principle, a stratospheric balloon can navigate in any desired direction simply by ascending or descending to the appropriate layer and harnessing the prevailing winds. Companies like Raven Aerostar have harnessed this technology, allowing balloons to hover over specific areas for extended periods, providing services such as communication coverage.

In the realm of stratospheric ballooning, technological innovations have facilitated remarkable progress. Balloons that once endured flights lasting mere hours have evolved to withstand weeks, months, and even over half a year in the upper atmosphere. The launch process, once manual and labor-intensive, has transitioned to automated systems with towering machines capable of sending a balloon to 60,000 feet in as little as 30 minutes. Furthermore, machine-learning algorithms have enabled balloons to execute complex navigational maneuvers, ensuring sustained service to users below. Communications equipment, which initially comprised makeshift components, such as beer coolers and WiFi routers, has evolved to deliver a coverage footprint spanning over 11,000 square kilometers—200 times that of an average cell tower. What was once a nascent commercial endeavor has transformed into a global initiative, featuring contracts across multiple continents and partnerships with major mobile network operators. This pioneering effort is spearheading the exploration and development of stratospheric capabilities while contributing to the formulation of the next generation of high-altitude operations, regulations, and policies within the global aviation community.

Zero Pressure and Super Pressure Balloons

Stratospheric balloons are categorized into two main types: zero pressure balloons and super pressure balloons. Open stratospheric balloons, or zero pressure balloons, are gas-filled with hydrogen or helium and feature one or more openings to maintain equilibrium between atmospheric pressure and the gas inside the balloon. These balloons typically remain aloft for no longer than a week and can carry payloads weighing up to 2700 kg at flight altitudes of up to 45,000 meters. They are constructed using thin polymeric films that serve as effective barriers, preventing the escape of lifting gas into the atmosphere. Structural analysis of zero pressure balloons is relatively straightforward, as meridional loads are supported by high-strength fibers sealed into the seams.

In contrast, super pressure balloons are sealed and boast envelope stability, enabling them to endure extended flights of up to 6 months. These balloons can carry payloads of up to 50 kg at flight altitudes of up to 20,000 meters. They employ extremely thin, high modulus, and high-strength elastic films, often made from materials like Mylar, to maintain gas containment throughout the mission. However, the size of the balloon and the weight of the scientific instruments are intrinsically linked, with increased instrument weight necessitating larger balloon volumes.

Pioneering Developments: Combining Heavy Lift and Long Duration

Researchers are actively exploring innovative balloon designs that merge the heavy lift capacity of zero pressure balloons with the extended flight duration associated with super pressure spheres. This concept involves the creation of pumpkin-shaped envelopes crafted from high-quality polyethylene film, supported by high-strength braided cables that bolster the payload. This innovative approach minimizes the stress in the circumferential direction and avoids the size limitations of superpressure spheres, offering promising possibilities for the future of stratospheric ballooning.

NASA’s ASTHROS Mission: Pushing Boundaries

In a groundbreaking endeavor managed by NASA’s Jet Propulsion Laboratory, the ASTHROS (Astrophysics Stratospheric Telescope for High Spectral Resolution Observations at Submillimeter-wavelengths) mission is set to carry an advanced 8.4-foot (2.5-meter) telescope high into the stratosphere using a massive balloon. Scheduled for a tentative launch in December 2023 from Antarctica, ASTHROS will embark on a three-week journey drifting on stratospheric air currents above the icy southern continent, achieving several pioneering feats.

ASTHROS will observe far-infrared light, which encompasses wavelengths much longer than those visible to the human eye. To accomplish this, the telescope must reach an altitude of approximately 130,000 feet—approximately four times higher than the cruising altitude of commercial airliners. While still below the boundary of space, this altitude allows ASTHROS to capture far-infrared light wavelengths that are typically obstructed by Earth’s atmosphere.

The telescope itself, consisting of an 8.4-foot (2.5-meter) dish antenna along with a series of mirrors, lenses, and detectors optimized for far-infrared light capture, is among the largest ever to fly on a high-altitude balloon. To ensure optimal performance, the telescope will be precisely controlled during the flight, with real-time data download facilitated through satellite links.

Unique Cryocooler Technology

Maintaining the required low temperatures for far-infrared instruments has traditionally involved the use of liquid helium. However, ASTHROS employs a cryocooler—a cooling device powered by electricity generated from onboard solar panels—to keep its superconducting detectors at a temperature slightly above absolute zero (-451.3 degrees Fahrenheit or -268.5 degrees Celsius). This innovation significantly reduces payload weight compared to the large liquid helium containers typically used for cooling. Consequently, the mission’s lifetime is no longer constrained by the availability of liquid helium.

ASTHROS’ Stratospheric Journey

The ASTHROS mission will involve the use of a substantial balloon that, when fully inflated with helium, spans approximately 400 feet (150 meters) in width—a size comparable to a football stadium. Suspended beneath the balloon is a gondola housing the telescope and its instrumentation. Throughout the mission, prevailing stratospheric winds will carry the balloon on two or three loops around the South Pole, with the entire journey spanning 21 to 28 days. Following the completion of scientific observations, flight termination commands will be issued to separate the gondola, equipped with a parachute, from the balloon. This process will ensure the safe return of the telescope for refurbishment and future missions.

In summary, the continuous innovation in stratospheric balloon technology, exemplified by missions like ASTHROS, is pushing the boundaries of scientific research, enabling observations and experiments that were once challenging or impossible to conduct. These advancements promise to unlock new frontiers in our understanding of the cosmos and the Earth’s atmosphere while expanding the possibilities for future high-altitude balloon missions.

Military and Security Applications of Stratospheric Balloons

However, there have been some instances where balloons have been used for espionage purposes, such as the use of balloons by the United States during the Cold War to gather intelligence on the Soviet Union. In these cases, special high-altitude balloons equipped with cameras or other surveillance equipment were launched from aircraft or ships and then flown into enemy airspace to gather intelligence.

Today, the use of unmanned aerial vehicles (UAVs), also known as drones, has largely replaced atmospheric balloons as a method of aerial surveillance. UAVs are smaller, more maneuverable, and can be controlled remotely, making them more effective for spying and surveillance purposes.

A Game-Changer in Intelligence: Recently, Stratospheric balloons have gained the attention of the military for their intelligence-gathering capabilities. Positioned at altitudes of 90,000 feet or higher, they offer a unique vantage point for surveillance and reconnaissance, making them ideal for monitoring activities in Anti-Access and Area Denial (A2AD) environments.

Stealth and Resilience: These balloons are stealthy, resilient, and capable of flying well above the reach of most surface-to-air missiles. They are challenging to shoot down, and even if damaged, they can continue to operate effectively. This makes them a valuable asset for gathering intelligence in hostile territories.

Surveillance in Denied Areas: Stratospheric balloons are particularly useful in gathering intelligence in areas where traditional aircraft cannot operate safely. They can remain aloft for extended periods, offering persistent surveillance over specific areas of interest.

Stratospheric balloons have garnered significant interest in military and security applications due to their unique capabilities. They offer potential game-changing advantages for gathering intelligence and surveillance in challenging environments. Here are key highlights of their military and security applications:

  1. Persistent Surveillance: Stratospheric balloons, such as World View’s Stratollite balloons, have been used for persistent surveillance. They can remain in a specific area of interest for extended periods, providing continuous monitoring and intelligence gathering, unlike low-earth satellites that pass overhead intermittently.
  2. Anti-Access and Area Denial (A2AD): These balloons address the challenge of collecting intelligence in A2AD environments where traditional aircraft cannot operate safely. They operate stealthily at altitudes of 90,000 feet or higher, making them virtually unreachable for most surface-to-air missiles. They are resilient to damage, as puncturing their envelope with shrapnel has minimal impact.
  3. Drone Deployment: Stratospheric balloons have served as launch platforms for drones. Chinese researchers successfully deployed drones from stratospheric balloons, demonstrating their ability to carry out missions at high altitudes and long distances. These drones are equipped with sensors for various purposes, including terrain mapping and electromagnetic signal detection.
  4. Unattended Ground Sensors (UGS): The U.S. Army is exploring the use of stratospheric balloons to deploy unattended ground sensors into signal-dense and contested areas. These sensors, disguised as rocks, gather data on radio communications, providing situational awareness. They support objectives like environment mapping, signal detection, and targeting for long-range precision fires.
  5. Cyber-Electromagnetic Environment Monitoring: Stratospheric balloons equipped with sensors can monitor the Cyber-Electromagnetic Environment (C-EME). They locate and track signals from Wi-Fi, cellphones, and military communication systems. This data helps identify enemy units, vehicles, and supports Cyberspace Situational Understanding (CYBER SU).
  6. Rapid Target Acquisition: Stratospheric balloons provide data for long-range precision fires. They identify and pinpoint targets, enabling accurate strikes with long-range missiles. Afterward, they offer battle damage assessment to determine the extent of destruction.
  7. IoT-Based Data Retrieval: These balloons may leverage Internet of Things (IoT) protocols for data retrieval from sensors. Sensors include GPS, CPU, memory storage, data retrieval capabilities, and power management systems, with potential for future expansions into various sensing modalities.
  8. Wind Sensing Technology: DARPA’s ALTA program incorporates wind sensors, such as Strat-OAWL (stratospheric optical autocovariance wind lidar). These sensors use lasers to deduce wind speed and direction, allowing balloons to adjust altitude and remain stationary. ALTA balloons can serve roles in secure communications, navigation, and supporting drones.
  9. Endless Flight Potential: Stratospheric balloons have the capacity for extended, possibly indefinite flights. This longevity opens doors to various applications, including secure communications, surveillance, and acting as platforms for other aerial assets.

In summary, stratospheric balloons hold immense promise in enhancing military and security operations. Their persistence, altitude advantage, resilience, and sensor capabilities make them valuable assets for gathering intelligence, monitoring critical areas, and supporting precision operations in challenging environments.


China’s High-Altitude Surveillance Balloons:

  1. China’s Contribution: China has made significant strides in the development and deployment of high-altitude surveillance balloons. These stratospheric balloons are part of China’s efforts to enhance its intelligence-gathering capabilities and expand its presence in near-space.
  2. Advanced Technology: China’s high-altitude surveillance balloons are equipped with advanced sensors and communication systems, allowing them to collect and transmit real-time data from the upper atmosphere. These balloons play a crucial role in monitoring border regions and gathering critical intelligence.


The Future of Stratospheric Balloons:

  1. Internet Connectivity: Stratospheric balloons are being explored as a means to provide high-speed internet access to remote and underserved regions. Initiatives like Google’s Project Loon have demonstrated the feasibility of using balloons to create networks that connect rural and disaster-affected areas.
  2. Advanced Sensors for Military Use: Researchers are developing low-cost, small, and lightweight sensors that can be deployed in large numbers from stratospheric balloons. These sensors can detect and locate various electromagnetic signals, enhancing situational awareness in signal-dense and contested operational environments.
  3. Integration with Cutting-Edge Technology: Stratospheric balloons are increasingly integrating advanced technology, such as laser-based wind sensors and cryocoolers for cooling instruments. These innovations improve their capabilities and extend their mission lifetimes.


Stratospheric balloons have come a long way since their inception, evolving into versatile platforms for scientific research, meteorological observations, and military applications. Their ability to reach extreme altitudes, endure harsh conditions, and provide persistent surveillance has made them invaluable assets. As technology continues to advance, we can expect stratospheric balloons to play an increasingly prominent role in our efforts to explore the upper atmosphere, bridge the digital divide, and gather vital intelligence in challenging environments. China’s contributions in the realm of high-altitude surveillance balloons underscore their growing importance on the global stage.














World View sees strong interest in stratospheric balloons despite test incident

World View, a company offering stratospheric balloon flights for research payloads, sees a bright future ahead for a platform that it argues combines the best attributes of satellites and aircraft, despite a recent testing incident at its Arizona headquarters.The company believes that its stratollites can loiter in the stratosphere for extended periods, providing persistence that aircraft cannot offer at costs much lower than satellites. Those flights have carried research payloads, including for NASA’s Flight Opportunities program, as well as commercial users, such as a summer 2017 flight that carried a chicken sandwich as publicity for a fast food restaurant chain.


One new application of World View’s balloons is in remote sensing. At the conference, the company released the first high-resolution images taken from its balloons, using off-the-shelf camera equipment. The images, taken from altitudes of more than 20 kilometers, have a resolution of 50 centimeters, but the company expects it can improve that, with better cameras and observing techniques, to as sharp as 10 to 15 centimeters.


Those balloon flights use helium, but at the conference Poynter said the company was looking to use hydrogen, which is much less expensive. “It is still on our radar. We have not done it yet, but we are very close to that,” she said. On Dec. 19, World View conducted a test of a hydrogen-filled balloon at its Tucson, Arizona, headquarters. At the end of the test, though, the balloon ruptured. Video of the test obtained by local news media shows the balloon bursting and what appears to be flames, suggesting hydrogen in the balloon combusted.


We have used hydrogen in ground testing, but only helium in flight operations at Spaceport Tucson,” he said, referring to the pad adjacent to the company’s headquarters, near Tucson International Airport, used for balloon flights. “However, to date our use of hydrogen has been limited to ground testing when required by customers or test objectives.” “As of now, we do not have any requirements or future plans for using hydrogen in ground testing or flight at the spaceport,” he added.


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