Stratolaunch, the world’s largest aeroplane by wingspan, has recently taken flight for the first time. The 117-metre wingspan aircraft entered the record books with its first flight on Saturday, April 13th 2019. But the future of this unique plane, dedicated to sending rockets into orbit, is more than uncertain.
It must theoretically be used to carry and drop at a 10-kilometre altitude a small rocket that will then light its engine, and will propel itself to outer space to place satellites in Low Earth Orbit (LEO). This is a more flexible and cheap method of accessing outer space, since a simple large take-off runway would suffice.
Will the huge Stratolaunch, built for Stratolaunch Systems (an American space transportation venture) by Scaled Composites (an American aerospace company founded by Burt Rutan) to carry air-launch-to-orbit rockets (the method of launching rockets at altitude from a conventional horizontal-take-off aircraft, to carry satellites to LEO), whose size is almost fifty percent larger than that of an Airbus A380, will have a more successful commercial career than that of the European airplane? Will it end up in a hangar after its first flight, like the Hughes H-4 Hercules, also known as the Spruce Goose, the previous record-holder in the world? The British did not have much more success with their project of the Bristol Type 167 Brabazon, a British large propeller-driven airliner, whose size exceeded that of a Boeing 747, but which never found a buyer and never exceeded the prototype stage…
The future of Stratolaunch is unclear since the death in 2018 of Paul Allen, co-founder of Microsoft, who had funded this company whose goal was to reduce the cost of access to outer space. The initial idea was to gain performance and flexibility by launching a rocket from an altitude of ten kilometres.
The two fuselages must allow to carry under the central wing a powerful rocket, with a mass of up to two hundred and twenty six tons, to send large satellites in orbit. Initially, in 2011, this rocket was to be provided by the private American company SpaceX, but seeing that the project required too much modification so that the rocket could be carried away by an airplane, SpaceX abandoned the project at the end of 2012.
Stratolaunch then turned to the American aerospace manufacturer and defense industry company Northrop Grumman Innovation Systems (formerly Orbital ATK Inc.) to develop a more powerful version of its air-launched Pegasus rocket, already launched by Stargazer. Stargazer, a Lockheed L-1011 TriStar built in 1974, was modified in 1994 to be used by Orbital ATK Inc. as a mother ship launch pad for Pegasus rockets; as of January 2017, forty-three rockets (containing ninety-four satellites) had been launched from it, using the Pegasus-H and Pegasus-XL configurations.
Finally, the American company now announces that its giant plane will only be able to carry a charge that will launch three small satellites, each weighing four hundred and forty kilograms, very far from the six tons that had to carry the launcher that should have been provided by SpaceX…
On paper, the idea of avoiding friction of the lowest layers of the atmosphere and of taking off a rocket with speed at high altitude is very attractive. Unfortunately, the performance advantage over a standard spaceport does not exceed ten percent. An ultimately small gain, which does not seem interesting when taking into account the operating costs of a giant carrier aircraft.
The legal status of Stratolaunch
Let’s first look at some definitions given by the Oxford English Dictionary. An aircraft is defined by the Oxford English Dictionary as an “aeroplane, helicopter, or other machine capable of flight”. An airplane (or aeroplane) is defined by the Oxford English Dictionary as “a powered flying vehicle with fixed wings and a weight greater than that of the air it displaces”. A spacecraft is defined by the Oxford English Dictionary as “a vehicle used for travelling in space”. Finally, a spaceplane is defined by the Oxford English Dictionary as an “aircraft that takes off and lands conventionally but is capable of entry into orbit or travel through space”.
In many articles, the object is presented as an aircraft. Plus, its first “flight” happened this way: it took off horizontally from the Mojave Air and Space Port, also known as the Civilian Aerospace Test Center (the first facility to be licensed in the United States of America for horizontal launches of reusable spacecraft), it then reached an altitude of seventeen thousand feet, flying at a speed of roughly one hundred and sixty-five knots, and finally landed after having flown for two and a half hours over California.
At first glance, we could say that this Stratolaunch is an aircraft. Let’s recall that “air navigation” is the set of techniques allowing an aircraft pilot to control his movements. Navigation allows the aircraft to follow a trajectory called “airway” or “air route”. Air navigation is largely heir to maritime navigation and the terminology used is identical. The Paris Convention of 1919 (formally, the Convention Relating to the Regulation of Aerial Navigation) was the first international convention to address the political difficulties and intricacies involved in international aerial navigation. It deals with the notion of aircraft and states in its Article 30 that “All State aircraft other than military, customs and police aircraft shall be treated as private aircraft and as such shall be subject to all the provisions of the present Convention”. The Convention on International Civil Aviation, also known as the Chicago Convention, established the International Civil Aviation Organization (ICAO), a specialized agency of the UN charged with coordinating and regulating international air travel. It talks about aircrafts and corroborates the definition of an aircraft enacted in the Paris Convention (and adds the notion of Pilotless aircraft in its Article 8 and thus, opens the horizons of flying objects).
The 1944 Chicago Convention does not define the term “aircraft” but Annex 7 defines it as “any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the Earth’s surface”. Under the 1944 Chicago Convention, aircraft have the nationality of, and remains subject to, the law of the State where it is registered. Each State’s domestic law determines eligibility and criteria for aircraft registration. The registering State has an obligation to ensure that its aircraft observes the rules of air safety and navigation locally in force.
The liability rules of the Warsaw Convention of 1929, or the more recent Montreal Convention of 1999, apply to the “international carriage” of persons or property by aircraft, though the term “aircraft” is nowhere defined in the treaties. Liability is imposed upon the air carrier. The Rome Convention of 1952 governs surface damage by aircraft. Liability of the aircraft operator is limited, based upon the weight of the aircraft.
Providing the way Stratolaunch operates, its aspects and how it has been publicly described, we could consider the object to be an aircraft. But, let’s now look at the definition of a space object.
The term Object in reference to outer space was first used in 1961 in General Assembly Resolution 1721 (XVI) titled International cooperation in the peaceful uses of outer space to describe any object launched by States into outer space. Professor Bin Cheng, a world authority on International Air and Space Law, has noted that members of the COPUOS during negotiations over the space treaties treated spacecraft and space vehicles as synonymous terms. The Space Object can be considered as the conventional launcher, the reusable launcher, the satellite, the orbital station, the probe, the impactor, the space telescope…
The term “space object” is not precisely defined by the Onusian space treaties. Let’s note that the five outer space treaties use such phrases as “objects launched into outer space”, object placed “in orbit around the Earth”, “in orbit around or other trajectory to or around the Moon”, or “around other celestial bodies within the solar system, other than the Earth”. Some of the treaties refer also to “spacecraft”, or “landed or constructed on a celestial body”, “man-made space objects”, “space vehicle”, “supplies”, “equipment”, “installations”, “facilities” and “stations”.
Let’s remember that “A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”, article 31 of the Vienna Convention on the Law of Treaties of 1969. In addition, “Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31: (a) leaves the meaning ambiguous or obscure; or (b) leads to a result which is manifestly absurd or unreasonable”, article 32 of the Vienna Convention on the Law of Treaties of 1969.
The term space object effectively triggers application of much of both the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (entered into force in October 1967) and the Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space (entered into force in December 1968). Article VII of the first declares that “Each State Party to the Treaty that launches or procures the launching of an object into outer space, including the Moon and other celestial bodies, and each State Party from whose territory or facility an object is launched, is internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air space or in outer space, including the Moon and other celestial bodies”.
The Outer Space Treaty doesn’t really provide a definition for “object launched into outer space” other than an indication in Article VIII that it includes the “component parts” of the “object launched into outer space”. It states that “A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or component parts found beyond the limits of the State Party to the Treaty on whose registry they are carried shall be returned to that State Party, which shall, upon request, furnish identifying data prior to their return”.
Let’s recall that a space object causing damage triggers international third-party liability under the Convention on International Liability for Damage Caused by Space Objects (entered into force in September 1972). Article I (d) of which enounces that “the term space object includes component parts of a space object as well as its launch vehicle and parts thereof”. Its Article II adds that “A launching State shall be absolutely liable to pay compensation for damage caused by its space object on the surface of the Earth or to aircraft in flight”. This is very interesting because it completes the definition of a space object by adding that a “launch vehicle and parts thereof” is included in the term space object.
The term launch vehicle is not defined by the five Onusian treaties but only mentioned twice: Article I (d) of the Convention on International Liability for Damage Caused by Space Objects and Article I (b) of the Convention on Registration of Objects Launched into Outer Space. A “launch vehicle” or “carrier rocket”, sometimes defined as “a rocket-powered vehicle used to send artificial satellites or spacecraft into space”, is a rocket used to carry a payload from Earth’s surface through outer space, either to another surface point (sub-orbital transportation), or into outer space (Earth orbit or beyond). A launch system includes the launch vehicle, launch pad, vehicle assembly and fuelling systems, range safety, and other related infrastructure. We could therefore consider Stratolaunch a launch vehicle (hence its name too), and therefore, a space object.
As a conclusion, whether Stratolaunch is a space object or not, Article VII of the 1967 Outer State Treaty enounces that “Each State Party to the Treaty that launches or procures the launching of an object into outer space, including the Moon and other celestial bodies, and each State Party from whose territory or facility an object is launched, is internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air space or in outer space, including the Moon and other celestial bodies”. The United States of America, from which Stratolaunch operates, will be internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air space or in outer space, including the Moon and other celestial bodies.
The future of orbital launch systems
Satellites launched from Earth require dedicated launch vehicles to propel them into the proper orbit. The cost for this launch scenario could be reduced considerably if there was another way to get the satellites into their optimal orbit. In the near future, we could see the development of new ways of launching objects in outer space. First of all, launches from aircraft could develop. Stratolaunch is not the first of its kind, since Stargazer, a Lockheed L-1011 TriStar built in 1974, was modified in 1994 to be used by Orbital ATK Inc. as a mother ship launch pad for Pegasus rockets; as of January 2017, forty-three rockets (containing ninety-four satellites) had been launched from it, using the Pegasus-H and Pegasus-XL configurations.
Also, LauncherOne, a two stage orbital launch vehicle is under development by Virgin Orbit since 2007. It is an air launch to orbit rocket (the method of launching rockets at altitude from a conventional horizontal-take-off aircraft, to carry satellites to Low Earth Orbit), designed to launch “smallsat” payloads of three hundred kilograms into Sun-synchronous orbit (a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet’s surface at the same local mean solar time), following air launch from a carrier aircraft at high altitude.
Let’s add that there are projects of sending satellites from balloons: Bloostar. Also, thanks to 3D printing, satellites might soon be built in outer space and launched directly from a satellite or from a space station. The Japan Aerospace Exploration Agency (JAXA) found a way to cut the costs of this activity by designing a small satellite launcher, installed recently on the International Space Station (ISS). The International Space Station was designed to be used as both a microgravity laboratory, as well as a launch pad for Low Earth Orbit services. The Japan Aerospace Exploration Agency’s (JAXA) Kibō module, or Japanese Experiment Module (JEM), a Japanese science module for the International Space Station (ISS), includes a small satellite-deployment system called the J-SSOD.
Deploying CubeSats from the ISS has a number of benefits. Launching the vehicles aboard the logistics carrier of the ISS visiting vehicle reduces the vibration and loads they have to encounter during launch. In addition, they can be packed in protective materials so that the probability of CubeSat damage during launch is reduced significantly. In addition, the Low Earth Orbit allows a natural decay of the satellites, thus reducing the build-up of orbital debris.
Let’s hope that those way to launch will reduce the cost of sending objects in outer space and thus, democratize access to outer space!