Gusts of change

February 2019

The world appears to be on the cusp of an explosion in personal and passenger air travel and commercial exploitation of space. It’s exciting, but the environmental and societal concerns of the coming revolution need to be considered starting now. Aerospace expert Amir S. Gohardani explains.

Dynamic gusts of change are the hallmark of the 21st century. Limited natural resources on Earth and an increase in global population make access to space and debates about ongoing air and space activities more relevant than ever. The solution to many looming environmental and societal challenges created by the aerospace sector lies in collaboration among those in different disciplines in addition to the identification of synergistic benefits between domains, such as artificial intelligence and aircraft flight control.

Here is the scope of the challenge: The World Bank projects the planet’s population to grow from 7.5 billion in 2018 to 11.2 billion in 2100, with over 80 percent of the world living in either Africa or Asia. If a large percentage of these communities receive packages via drones, fly to work every day, and fly halfway around the world, the environmental impacts of these developments would be enormous.

Technical advances have always posed environmental and societal tradeoffs. Consider the creation of the telegraph as described by historian Tom Standage in his book “The Victorian Internet.” In the 1850s, Paul Julius Reuter, the founder of the Reuters News Agency, delivered news and stock prices to customers via a combination of telegraph cables and carrier pigeons. Determined to offer timely information between Aachen and Brussels, Reuter increased the number of carrier pigeons — exceeding 200 pigeons — in pace with increasing demand. He operated this service for a year until a gap in the telegraph link was finally closed. The future of aerospace technologies bares many resemblances to this historical case.

Swarm of drones

For the aerospace industry, a near-term opportunity and challenge is the advent of drone technologies in our everyday lives. The massive explosion of drones in the consumer market and the operational history of larger drones such as the Predator within the U.S. military and defense sector, showcase how a specific technology can affect society. Two decades ago, pipeline monitoring had to be carried out by a specially designed aerial platform or a military drone whereas today it is possible to use an off-the-shelf quadrotor equipped with a camera and achieve the same objective. The ongoing drone trends raise a legitimate question: Does technology, policy, or society fuel the drone trends?

In a throwback to Reuter’s carrier pigeon solution, one can answer this question in several ways. The short answer is, naturally, that it all depends. Initially, it appears as if these trends are simply driven by supply and demand. In recent years, the toy market identified the demand for toy drones and this resulted in a favorable marketplace for these products based on the colossal consumer demand. Similarly, the use of pigeons as a replacement for the telegraph was a short-term solution propelled by the demand for information. In absence of any pre-existing policy bans, a timely policy was adopted for using pigeons as information carriers. In the case of future aerial drones, unless other robust and efficient technologies would be available in the marketplace to challenge aerial drones, it would be difficult to imagine that drone package deliveries would not be adopted, particularly if safe deliveries are made and smooth and noncongested transportation routes are rigorously established. In February 2018, a study published in Nature Communications and led by researchers at Lawrence Livermore National Laboratory and Carnegie Mellon University found that using relatively small quad- or octocopters (compared with larger military drones, for example) instead of diesel-burning delivery trucks could mean a reduction in both energy consumption and releases of greenhouse gases that contribute to climate change.

Nonetheless, policy crafting and adoption are truly convoluted processes. In case of unmanned aerial systems, policy crafting is likely to enter the scene if drone technologies and the demands of society were to invade public privacy or unfavorably disrupt the societal norms through, for instance, unethical approaches, or mishaps. Contemplate, for instance, scenarios in which a large number of drones accidentally or deliberately overload and interfere with the adopted policies in the developing UAS traffic management systems. A version of this scenario unfolded in the United Kingdom late last year. According to news reports, between Dec. 19 and 21, hundreds of flights were canceled and the runway was closed at Gatwick Airport, due to drone sightings. This incident caused major travel disruption, affecting about 140,000 passengers and over 1,000 flights. On Dec. 21, 2018, Sussex police arrested two suspects, who were released without charge on Dec. 23, 2018. Thus, through this incident, the unfortunate vulnerability of air travel was exposed with only a limited number of drones operating in the skies. Consequently, concerns about undesirable scenarios affecting societal safety and security are legitimate considerations given the increasing number of aerial platforms.

As partially alluded to earlier, policies need to take public privacy into consideration and account for the possibility of misuse and illicit activities. This is rather similar to the case with Reuter’s carrier pigeons if one imagines a fictitious scenario in which a large invasion of pigeons would cause disruptions to the normal procedures and the flow of life in either Aachen or Brussels. Surely, such interruptions would not remain without any consequences. Likewise, drone technologies are considered beneficial or detrimental based on their impact. In short, if drone utilization does not paralyze societies or invoke privacy or safety concerns as in the case of Gatwick Airport, they could potentially prove to be advantageous. Nonetheless, it should also be noted that drone deliveries made to urban areas might invoke a different set of privacy concerns than those considered for remote areas. Through this hypothetical exercise, it is readily evident that drone use is not explicitly confined or driven by the technology sector. In effect, regardless of the concerns about drone use and whether or not they are related to noise, line-of-sight issues, or any other factors, from a holistic perspective, the intersections among technology, policy and society dictate the final impact of drone utilization in our future societies.

Green aerial and space transportation

Originally, throughout the technical evolution of air and space transportation systems, the environmental impacts of these vehicles were viewed secondary to their enabling technologies. Following the decision to phase out lead as an ingredient of automotive gasoline in the early 1970s, aviation fuel became the largest source of lead emissions in the United States. Today, the majority of commercial aircraft do not burn leaded fuel, but piston-engine planes continue to burn the leaded aviation fuel (nicknamed avgas). According to scientists at the U.S. Department of Health and Human Services’ National Toxicology program, lead and lead compounds are reasonably anticipated to be human carcinogens. EPA further estimates that 16 million people live close to one of 22,000 airports where leaded avgas is used, and about 3 million children go to schools near these airports.

Even though it has been established that lead is extremely toxic to humans, wildlife and the environment, and causes health problems even at low doses, there are no plans to ban leaded aviation fuel in the U.S. In 2018, the FAA temporarily suspended flight testing and certain engine trials of the two drop-in unleaded fuel options. These were under evaluation to replace leaded aviation gasoline through the Piston Aviation Fuels Initiative. The suspension resulted in a delay in testing completion from December 2018 to mid-2020.

The impact of aviation on the environment has always been an interest of NASA. Thus, it is not merely coincidental that NASA has pursued initiatives such as the ERA, for Environmentally Responsible Aviation, project. Some of the goals were to enable reduced fuel burn, emissions and noise for futuristic air vehicles. These goals have independently been pursued by the aviation industry for decades and partially motivated additional measures to electrify air vehicles into hybrid electric aircraft, more electric aircraft, and all-electric aircraft concepts. Following the ERA project, aircraft designers are looking at more sustainable options to fly aircraft from point A to point B. Some of these options include changing the airframe to a blended wing body or hybrid body concepts, using alternative fuels such as biofuels and designing new aircraft power management and distribution architectures.

Environmental effects could have a larger impact in the future. According to FAA’s Aerospace Forecast report for fiscal years 2018-2038, the number of aircraft in the U.S. commercial fleet is predicted to increase from 7,141 in 2017 to 8,290 in 2038, an average annual growth rate of 0.7 percent. Increased demand for air travel and growth in air cargo are expected to bring increases in the passenger and cargo fleets. With an increase of aerial transportation around the globe, the ability to sustain such growth is likely to be influenced by environmental constraints. For instance, if there are no alternative aircraft fuel options available and the aviation industry were to encounter a fossil fuel shortage, the industry would fail to meet the mobility demands and its projected annual growth rate. Yet, the switch to more sustainable aviation is unlikely to gain momentum in the absence of business incentives or measures by global bodies targeting aircraft emission reductions. In 2016, the International Civil Aviation Organization agreed on a resolution for a global market-based measure that would reduce CO2 emissions from international aviation as of 2021. The Carbon Offsetting and Reduction Scheme for International Aviation, or CORSIA, aims to stabilize CO2 emissions at 2020 levels by asking airlines to offset the growth of their emissions after 2020. Moreover, inefficient utilization of infrastructures that do not support new flight routes from remote areas will contribute to additional hurdles related to airport and air traffic congestion.

Environmental concerns for space activities are equally as important as those for the aviation sector. Reusable rockets and calls for daily space travel mark a technical evolution and vision for future space transportation. In an analogy to the switch from pigeons to the telegraph, reusable rockets lead to a greener approach in comparison to nonreusable rockets. In Reuter’s service, mortal pigeons were replaced with a virtually immortal telegraph system that did not depend on the lifespan of living creatures. Hence, the reusability of rockets is analogous with that of the telegraph system.

In line with an anticipated increase of space transportation activities and efforts to minimize environmental impact, green space propellants are already being investigated as replacements for hydrazine rocket fuel, a highly toxic and carcinogenic chemical. If the policy adoption framework expands beyond the sole use of chemical propulsion in space, then electric space propulsion or a combination of chemical space propulsion and electric space propulsion for several space missions has already been suggested. Just as in air transportation, weight is a big concern for spacecraft. The fact that space electric propulsion provides a much higher specific impulse means the requirements call for less propellant — in comparison to chemical propulsion — and contributing to an overall lighter spacecraft. Hence, the option for a more sustainable solution utilizing electric space propulsion is available if it is in line with the overall mission objectives and in case the intended propellants are environmentally unfriendly. On the flip side, because an electric space propulsion device provides lower thrust, it must run for a longer period to produce the desired change in trajectory or velocity. Therefore, it could be ideal for a deep-space probe. Human presence in orbit contributes to additional design constraints and new calls for a thorough understanding of a radiation environment that affects human health.

A connected world

Reuter’s past ambitions to share information resonates with the Information Age in which many aspire for global connectivity. One of the key objectives of the planned satellite constellations in orbit is to enable an unprecedented capability of reaching remote areas of the globe for communication purposes. Global connectivity could prove to be beneficial for humanity’s progress in a world with consistent population growth. However, there is a dormant risk to space sustainability. In the case of cubesats, for instance, they have indeed proved to be beneficial for scientific and educational purposes. Be that as it may, there is a risk that technical glitches and inadequate oversight of operation of cubesats and other satellite constellations could contribute to the theoretical Kessler syndrome in which the density of objects in low Earth orbit is high enough that collisions could cause a cascade in which orbital debris increases the likelihood of further collisions. Therefore, the orbital debris threat is imminent and undoubtedly remains a likely disruption to many current and future space activities. With many ambiguities revolving around orbital debris and policy, legal uncertainties that pour into national defense and international concerns, a solution inspired by the fusion between policy and technology would be optimal for minimizing the threat of orbital debris and enabling sustainable space architectures for a connected world.

The global community would indeed greatly benefit from a sustainable environment in which many space and aerial activities could take place without major disruptions and disasters. Communication across a number of multidisciplinary subject areas and a thorough understanding of how technology interacts with society and policy is a future requirement for such endeavors.

Amir S. Gohardani. Credit: Courtesy

A SpaceX Falcon 9 booster lands back in Florida after launching Es’hail-2, a communications satellite owned by Qatar Satellite Co. Credit: SpaceX

A NASA HU-25C Guardian aircraft flies behind NASA’s DC-8 aircraft before it descends into the DC-8’s exhaust plumes to sample ice particles and engine emissions. Credit: National Research Council of Canada

NASA’s DC-8 research aircraft leads an aircraft collecting exhaust samples. Credit: NASA