Rocket Launches: Pollution, Impact, And Our Future

Rocket launches are an integral part of the 21st century, with the billionaire space race and the growing space tourism industry. However, this also means that the number of rocket launches is increasing, and with it, the pollution they cause. Rocket engines burn huge amounts of fuel, which is then spewed out as emissions into the atmosphere, and this is expected to cause an environmental crisis in the future. The exact implications of rocket propellant emissions on the climate remain unclear, but it is evident that this issue will grow and affect the Earth.

Rocket fuel and emissions

Rocket engines, like any combustion-driven propulsion, emit pollutants into the atmosphere. The type of fuel used determines the kind of air pollutants that are emitted during the launch process. Rocket Propellant-1, or RP-1, a highly refined form of kerosene, is one of the most popular rocket fuels. RP-1 is cheaper, stable at room temperature, and not dangerously explosive. However, RP-1 fuelled rockets produce soot and carbon dioxide, a greenhouse gas responsible for climate change.

Other fuels, such as methane, hydrogen, and hydrazine-based hypergolic fuels, are also used in rocket engines. Methane is considered environmentally friendly due to its high burning efficiency, resulting in minimal residues. Hydrogen or methane-powered rockets can become carbon-neutral if the fuel production is powered by renewable energy sources. However, in practice, most hydrogen is produced from fossil fuels, making it unsustainable. Additionally, methane is controversial as it is a potent greenhouse gas, with a much higher warming effect than carbon dioxide. Solid rocket boosters, commonly used in the first stage of rockets, are considered the dirtiest form of rocket propulsion, producing over 85% of the thrust at takeoff.

Several rocket startups are experimenting with sustainable alternatives to RP-1, such as biopropane and biomass. For instance, Orbex, a UK-based company, is developing a 3D-printed micro-launcher that runs on biopropane, which is expected to produce significantly fewer emissions and less soot than RP-1 fuelled rockets. SpaceX's Raptor and the European Space Agency's Prometheus engine are designed to use gas as fuel, resulting in higher performance and reduced soot emissions.

The exact impact of rocket propellant emissions on the climate remains uncertain due to limited research. However, it is evident that the increasing demand for space services and the growing space tourism industry will exacerbate the issue.

Climate change

Rocket launches are a source of pollution, and with the space industry's growth, the number of launches and the size of rockets are increasing. This increase in launches contributes to the surge in emissions, which affects the Earth's climate and ozone layer. The emissions from rocket engines contain gases and particles, with the most common gaseous emissions being water vapour and carbon dioxide from liquid and solid fuels, as well as hydrochloric acid from solid fuels. The impact of these emissions on the climate has been historically overlooked due to the infrequent nature of rocket launches and the relatively small size of the space industry compared to other industries. However, with the anticipated increase in launch frequency, the climate impact of rocket emissions is expected to become more significant.

The type of fuel used in rockets also plays a role in their environmental impact. For example, SpaceX's Starship spacecraft uses methane instead of kerosene, which burns cleaner and produces less black soot. In contrast, the fuel used at the Baikonur Cosmodrome, the world's oldest spaceport, was UDMH (unsymmetrical dimethylhydrazine), dubbed "devil's venom" due to its highly carcinogenic nature and its ecological impact on the surrounding steppe.

The particles emitted by rockets are particularly efficient at holding heat in the atmosphere, with studies showing that black carbon emissions will more than double after just three additional years of space tourism launches. This increase in emissions will have a warming effect on the climate, potentially undermining the recovery of the ozone layer achieved after the Montreal Protocol. While the current loss of ozone due to space launches is small, the cumulative effect of increased launches and emissions will have a significant impact on the Earth's climate.

It is important to note that the space industry also provides benefits, such as the collection of climate data by satellites. However, the anticipated surge in rocket emissions, particularly from space tourism, underscores the need for further scientific study and mitigation strategies to address the climate impact of rocket launches.

Environmental impact

Rocket launches are an integral part of the 21st century, but they also contribute to air pollution and climate change. The pollution caused by rocket emissions may seem insignificant compared to other challenges, but it is a growing concern as the rate of launches increases. The composition of rocket propellants determines the type of air pollutants emitted during launch, with carbon dioxide (CO2) being a significant issue. Rocket launches generate between 50-75 tonnes of CO2 per passenger, in comparison to 1-3 tonnes of CO2 per passenger on a typical long-haul plane flight. The increase in launch rates is evident, with 144 missions in 2021 and a record-setting 180 launches in 2022.

The impact of rocket emissions on the atmosphere, temperatures, and the ozone layer is a growing area of research. While the amount of pollution emitted by rocket launches is relatively small compared to aircraft, the comparison may be erroneous. Aircraft release pollutants in the troposphere and lower stratosphere, while rockets release pollutants from the surface of the Earth up to the mesosphere. Pollution released into the upper layers of the atmosphere lasts longer and has a more significant impact. Rocket soot, for example, can remain in the stratosphere for up to five years, absorbing solar radiation and contributing to global warming.

The type of fuel used in rockets also affects the environmental impact. Unsymmetrical Dimethylhydrazine (UDMH), also known as "devil's venom", was used in many early rocket launches, including those from the Baikonur Cosmodrome in Kazakhstan. UDMH is highly carcinogenic, and it is blamed for turning a large area of the Kazakh steppe into an ecological disaster zone. More recently, rockets have used a mixture of liquid oxygen and kerosene, which produces black soot that contributes to climate change and damages the ozone layer. SpaceX's Falcon 9, the most active rocket in the US, is a major contributor to rocket soot.

Some companies are experimenting with sustainable alternatives to traditional rocket fuels. For example, Orbex, a UK company, is developing a 3D-printed micro-launcher that runs on biopropane, which could produce 86% less emissions than similar-sized RP-1 fuelled rockets. Blue Origin's New Shepard rocket is even cleaner, burning liquid oxygen and liquid hydrogen and producing only water vapour as exhaust. While these alternatives are promising, the growing demand for space tourism and satellite internet services could still lead to a significant increase in rocket launches and their environmental impact.

Air pollution

The impact of rocket launches on air pollution is a complex issue that is currently the subject of ongoing research. While rocket launches are relatively infrequent compared to aviation, the propellants used can release significant amounts of carbon dioxide (CO2) and other pollutants into the upper atmosphere. For example, a typical long-haul plane flight produces between 1-3 tonnes of CO2 per passenger, while a rocket launch can generate between 50-75 tonnes of CO2 per passenger. Rocket launches can also emit other pollutants such as nitrogen oxides and soot, which have been linked to ozone depletion and climate change.

The type of propellant used in rocket launches determines the specific air pollutants emitted. Rocket Propellant-1 (RP-1), a highly refined form of kerosene, is one of the most popular fuels due to its stability, low cost, and non-explosive nature. However, the burning of solid rocket fuels can result in a significant carbon footprint, while liquid hydrogen fuel produces 'clean' water vapour exhaust. Nonetheless, the production of hydrogen can also lead to carbon emissions.

The altitude at which rocket emissions are released is an important factor in understanding their impact on air pollution. Unlike aircraft emissions, which are released in the troposphere and lower stratosphere, rocket pollutants are discharged from the surface up to the mesosphere, or even higher. This means that the pollutants can persist for longer periods and have a more prolonged impact on the atmosphere.

The increasing frequency of rocket launches and the expected growth in the space industry, including space tourism, highlight the urgency of addressing this issue. Experts warn that if no action is taken within the next few years, the world could face another major environmental crisis. While the exact impact of rocket launches on air pollution is not yet fully understood, it is clear that this topic warrants further investigation and preventive measures to mitigate any potential harm to the environment.

Some efforts are being made to explore sustainable alternatives to traditional rocket propellants. Startups are experimenting with biofuels and waste products to reduce emissions and carbon footprint. These technologies are still in their early stages, but they show promise in making spaceflight greener and less polluting.

Space tourism

Rocket launches are an integral part of the 21st century, with applications in satellite internet services, space tourism, and scientific research. However, the increase in rocket launches has brought attention to the environmental impact of these ventures. While the number of rocket launches is currently low compared to commercial flights, the growth in demand for space tourism is expected to significantly increase the number of launches in the coming decades. This raises concerns about the potential impact on the environment, specifically the protective stratospheric ozone (O3) layer and climate change.

The impact of space tourism on the environment has been studied by researchers, who have found that black carbon emissions will more than double after just three additional years of space tourism launches. The particles emitted by rockets are almost 500 times more efficient at holding heat in the atmosphere than other sources of soot, leading to an enhanced warming climate effect. This warming effect can cause significant temperature anomalies in the stratosphere and interfere with the Earth's magnetic field, allowing more harmful cosmic radiation to reach the planet's surface.

Additionally, the increase in rocket launches will result in more space debris falling back to Earth. This includes old satellites and spent rocket stages, which contribute to air pollution and can create an environmental crisis if left unchecked. The impact of space tourism on the ozone layer is also a concern, as the emissions from rockets can deplete the ozone and expose the planet to dangerous ultraviolet (UV) radiation. The success of the 1987 Montreal Protocol, which banned substances that deplete the Earth's ozone layer, could be undermined by the increase in rocket launches and the resulting emissions.

While the space industry brings numerous benefits and advancements, it is crucial to address the environmental impact of space tourism and find ways to mitigate its effects on the atmosphere and climate. This includes reducing the use of polluting fuels, regulating air pollution from rocket flights, and conducting more research on the potential impact of rocket engines on the stratosphere and climate. As the demand for space tourism grows, addressing these issues becomes increasingly urgent to ensure that the benefits of space exploration do not come at the cost of environmental degradation.

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