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According to Aviation Week, the Swedish Air Force has begun studying the possibility of launching satellites from the JAS-39 Gripen fighter. The project is named "Stella" and is jointly carried out by the Swedish Air Force's space department and the Swedish National Defense Research Institute.

The direct factor that gave rise to this research was to achieve the rapid response launch of satellites with specific functions. The deeper reason behind it was the change in the Swedish government's space strategic policy.

JAS-39 Gripen fighter

According to Aviation Week, on July 21, on the eve of the opening of the 2024 Farnborough Air Show, Ella Carlsson, head of the Swedish Air Force Space Capabilities and Development Department, told reporters at the annual gathering of the Swedish Air Force Fan Club that the birth of the "Stella" project was largely influenced by the former director of the Ukrainian Space Agency. The former director once said that in the face of a country like Russia, in the event of a full-scale military conflict, if an aircraft can be used for the rapid emergency launch of satellites, it will bring significant help to the national strategy.

In fact, according to a report on the Swedish Broadcasting Corporation website, the Swedish Air Force has been considering launching satellites via the Gripen since September 2023. Carlsson has said that while it is currently possible to launch satellites at the Eslang Spaceport in the Arctic city of Kiruna, the Swedish military also wants to explore other options in case of war.

The space under the belly of the JAS-39 is very limited.

However, it is obvious that JAS-39 is a lightweight aircraft equipped with only a single medium-thrust engine.fighter, its empty weight is only 6.8 to 8 tons. Whether it is the load weight limit brought by the take-off weight or the load size limit brought by the ground clearance of the centerline of the belly, the air-based launch rocket that can be carried is destined to be very "pocket" - the satellite that can be carried is very small, and the orbital altitude will not be too large.

Carlson said that the KTH Royal Institute of Technology in Stockholm, Sweden, has conducted a preliminary study on the feasibility of the project and believes that the air-launched rocket carried by the JAS-39 can launch a 2-kilogram satellite. The next step will be to examine the impact of the ground clearance of the aircraft's belly on the safety of take-off and landing, and focus on how such rockets can be safely carried and launched by the JAS-39.

Considering that a 2-kilogram satellite cannot carry various sensor communication payloads with complex functions and high performance indicators, the satellite capability ceiling brought by the JAS-39's launch capability is actually very low. In addition, since Sweden does not rely solely on its own military strength to face potential military threats independently (it officially joined NATO in March this year), the Swedish Air Force and Saab have drawn a clear boundary for the "Stella" project: they will not pay the huge economic cost of changing the JAS-39 fuselage design in order to cater to the function of launching satellites.

This decision is also in line with Sweden's usual decision-making style: it has very strict control over military spending - the JAS-39 is one level smaller in weight and size than the earlier JA-37, and the core purpose is to reduce costs.

The Typhoon's high altitude, high speed and mounting capacity are far superior to those of the JAS-39, which gives it a much greater performance advantage in launching satellites.

Compared with Sweden, Italy is also considering developing the same capabilities. According to Aviation Week, in September 2019, the Italian Air Force and industry worked with academia to establish a framework agreement to explore the feasibility of launching small satellites from Italian fighter jets: Compared with the Gripen, Italy's EF-2000 European fighter is a more ideal air launch platform and has more potential in practicality than Sweden.

So far, there are very few air-based launch vehicles launched from aircraft, and all of them are based on transport aircraft. Because, in order to ensure the functions and performance indicators of satellites, the weight and size of air-based launch vehicles cannot be made very small, and usually far exceed the specifications of mainstream auxiliary fuel tanks and air-to-ground weapons of tactical aircraft.

Pegasus-XL rocket launch.

For example, the Pegasus-XL air-based launch vehicle, which has already been put into practical use, can send a 443-kilogram satellite into low-Earth orbit, but it weighs 23.13 tons, is 17 meters long, and has a diameter of 1.27 meters. It also has a pair of delta wings with a wingspan of 6.7 meters, which cannot be carried by a fighter jet anyway.

Later, Virgin Orbit's LauncherOne rocket was even heavier and larger than Pegasus XL.

According to the classification of wet mass (including fuel), fighter jets can only launch nanosatellites (1-10 kg) and microsatellites (10-100 kg), and cannot even launch small satellites (100-500 kg). The actual value of fighter jets' responsive satellite launch ultimately depends on one point: what role can a nanosatellite weighing a few kilograms or at most a dozen kilograms play after being launched into low-Earth orbit?

The main military use of micro-nano satellites is to achieve various tasks such as observation, communication, remote sensing, reconnaissance, communication relay, and navigation through the mutual coordination of multiple satellites. This coordination can be in the form of a simple constellation combination. There is no fixed distribution configuration requirement between satellites. The ground coverage characteristics are maintained through single-satellite orbit control. There is no need to maintain closed-loop control between satellites, nor is there a need for information exchange and services between satellites. At the same time, a more complex and advanced satellite networking form can also be adopted to decompose the functions of a larger single traditional satellite into multiple different satellites, which coordinate with each other through wireless links.

A 6U cubesat-sized nanosatellite platform with communication and attitude control systems, which can be equipped with payloads of other functions such as cameras as required.

Due to the low cost of micro-nano satellites, in theory, they can be replaced and updated at any time, launched quickly, and form a quantitative advantage. Due to the miniaturization of high-performance devices brought about by the rapid progress of electronic technology, new micro-nano satellites can now perform tasks that previously required a larger satellite. For example, under the same mission cost limit, a 6U specification (approximately 30x20X10 cm) and 35 kg earth imaging satellite constellation under the CubeSat standard can replace the original set of 5-star fast-eye earth imaging satellites weighing 156 kg, and the revisit time interval is greatly shortened from once every 24 hours to once every 3.5 hours.

Astrid-1 satellite, launched in 1995, weighs 26 kg.

From the current situation, Sweden's main demand for fighter-launched nanosatellites is to carry out reconnaissance missions such as image taking of designated areas and provide real-time or semi-real-time image data to ground units, especially combat-ready forces.

Sweden has relatively rich engineering experience in the research and development of micro-nano satellites. For example, the Swedish Aerospace Corporation developed a variety of micro-nano satellites such as Astrid-1 and Astrid-2 for the Swedish National Space Agency in the early years.

Cosmos-3M rocket launch.

It is worth mentioning that Astrid-1 and Astrid-2 were previously launched by Russia's Cosmos-3M light launch vehicle from the Plesetsk Cosmodrome in Russia. The new nanosatellite that may be launched by JAS-39 in Sweden itself has Russia as its biggest imaginary enemy... In less than 20 years, the geopolitical landscape of Europe has undergone tremendous changes, which is impressive.