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Aiming High: What is Air Launch?

Launching a satellite from an aircraft moving in the sky is not a simple operation, and its advantages over ground launch are disputed. Tal Inbar reviews the history of air launch and the challenge it poses to Israeli space exploration

Rear view of Spaceship_One mounted on White_Knight. Source: Rokits XPrize gallery
Rear view of Spaceship_One mounted on White_Knight. Source: Rokits XPrize gallery
Tal Amber, Galileo

Launching a satellite into space is a dramatic, expensive event, involving many people and complex technological systems. Such a launch has aspects that go beyond simply sending a satellite into space. The dramatic images of launches from launch vehicles engulfed in flames and smoke are familiar to every reader; However, the field of space launches is not limited only to satellite launchers standing on the ground.

The field of air launch holds many advantages for the future of satellites, but there are also other opinions coming from industry, academia and the field of space policy that question these advantages. So what is it actually? air launch?

An aerial launch consists of a satellite launcher (missile) that is carried into the air by an aircraft. There may be various configurations of carrying - under the belly, over the body, under the wing or inside the plane - but the principle is the same: carrying the launcher to a height and dropping it, with or without parachutes.

When the launcher moves away from the carrier plane, its rocket engine is activated. The basic idea of ​​an aerial launch is to save the stage of the launcher, since it does not start its journey from ground level and at zero speed, but at a speed close to 1,000 km/h and at an altitude of at least ten km.

It is assumed that smaller and cheaper launch missiles could be used if carried into the air. In addition to energy savings - since the carrier plane is used as the first stage - there is greater flexibility in choosing the launch direction, while freeing up a complex and stationary ground launch system.

From the light to the heavy
A light air launch is a light dedicated launcher, portable, on fighter planes (such as the F-15). Such a launcher can be developed on the basis of existing technology (such as the "Black/Blue Anchor", a surface-to-surface missile imaging system developed by Rafael).

Such a launcher would allow the launch of only one microsatellite from an aircraft or a cluster of nanosatellites. On top of that, the development of a completely new launcher that does not rely on this or that missile is possible. In the world there are various proposals for the use of fighter jets to launch satellites, most of them deal with launching satellites weighing as little as 70 kg.

Compared to the light launch, the concept of a heavy air launch is based on carrying a conventional and not small satellite launcher inside a large transport plane (such as a C-17, Ilyushin 76, etc.), dropping it through the rear loading hatch of the plane and launching it from the air. An example of such a launcher is the Israeli satellite launcher "Shavit".

The launcher will initially be attached to a cargo platform that will fall with it from the plane, and an array of stabilization parachutes will help achieve the appropriate angle for launch. In the past, the possibility of launching a large ballistic missile from the American Galaxy transport plane was successfully tested. Today there is no obstacle to launching satellite launchers larger than airplanes, and this alternative has technological, economic and operational justification.

looking back
Different concepts dealt with air launch, some of them were used as far back as the sixties of the 20th century. Thus, for example, there was a proposal to launch the American X-15 test plane into space from the back of a B-70 bomber. In the USSR, the design of the "Spiral" space plane was started by the "MIG" planning office. This space plane was supposed to fly into space on the back of an oversized carrier plane.

In the XNUMXs and XNUMXs, many plans for launching space planes and small space shuttles were examined in Great Britain, Germany, Japan, the USA and Russia. Neither program matured into an operational tool, mainly due to cost and benefit considerations.

The only operational aerial satellite launcher in the world today is "Pegasus", launched from a Lockheed Tristar aircraft. It is a solid propellant three-stage launcher. The launcher has a wing that provides lift during the first stage combustion. In the past, the manufacturer of the launcher made many promises that air launch is cheap, but reality shows otherwise - Pegasus is not economical and is massively supported by the US government.

The private spaceships Spaceship 1 and 2 are launched from the air, from a dedicated aircraft flying at high altitude. In the future, the developers of the spacecraft intend to use the carrier plane also to launch satellites. Also, the possibilities of using UAVs (unmanned aerial vehicles) for launching satellites are being examined in various places.

Despite decades of promises and plans, a single, expensive, inflexible, complex and cumbersome aerial launcher is in use. One of the arguments of the supporters of air launch is to neutralize the need for the complex ground system. is that so?

It is necessary to use telemetry (transferring data from the missile to the control center), therefore there is a need for an additional control plane on the launching plane or for operating a highly complex satellite communication system; Photography to track the separation of the phases is necessary - and it is not easy to photograph from the air; And the presence of a safety officer who can destroy the missile in the event of a malfunction is mandatory. The officer must be in the air in the launching aircraft or in another aircraft.

Moreover, the combinations of the satellite in the missile and the missile itself and its assembly in the carrier plane are complicated. In fact, except for the issue of safety close to the launch site, air launch is not simpler than ground launch but more complex.

Israel and air launch
Because of Israel's location near enemy countries, it is unable to launch satellites towards the east, as is customary in the world, and therefore Israel's launch missiles are launched west, against the direction of the Earth's rotation. Due to this, an energy loss of up to 40 percent of the missile's lifting capacity was caused.

If it were possible to launch to the east, it would be possible to almost double the weight of the Israeli satellites without any changes to the launcher. Therefore, various alternatives that allow breaking away from Israel's limited launch space - such as air launch - have been beckoning to various parties in Israel for years.

The concept of Rafael scientists, which advocates launching satellites from fighter jets, is an innovative breakthrough in the field of space. At its center is the idea that launching microsatellites from fighter jets enables the miniaturization of launchers and their cheapening. Rafael believes that it is possible to launch small satellites weighing close to XNUMX kg into space without any particular difficulty.

In the past, the Aerospace Industry examined various possibilities of carrying the Shavit satellite launcher under or inside large transport planes, and some of the studies were presented to the public in 2009.

The former commander of the Air Force, Lt. Col. Eliezer Shakdi, spoke out back in 2007 at the Ilan Ramon Space Conference due to the concept of air launch and micro satellites. Major General Ido Nehushtan, the current commander of the corps, also supported this matter at the conference held this year. However, a development plan for such a launcher accompanied by a suitable satellite has yet to be launched.

Looking ahead
Various designs for aerial satellite launchers are repeatedly presented at various professional conferences. However, so far none of these designs has become an operational launcher. The question arises - why? Is air launch considered a "solution looking for a problem"? It seems that in some cases the answer is apparently positive.

It seems that the operational need to launch satellites on demand to a designated orbit and at very short notice is not that urgent. Furthermore, the low carrying capacity of small satellite launchers carried into the air by fighter jets dictates the construction of small satellites with relatively inferior performance.

In conclusion, the concept of Responsive Space, which advocates faster access to space, with modular satellites, on-demand launches, etc., requires the use of an aerial launch - however, this is only one of several possible alternatives, in which, for example, satellites can be placed in a "dormant" state on a "parking track" /Standby" in the space and activate them when necessary.

Tal Inbar is the head of the Center for Space Research, the Fisher Institute for Strategic Air and Space Research, and the chairman of the Israel Space Association.

Link to image source

One response

  1. Has Israel considered launching a satellite from the sea, like the Sea Launch company?
    This can solve the launch space problem.

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