How sustainable is Elon Musk's Starship?

A day for the history books, engineers at SpaceX declared that the booster had landed safely.

The chances of the bottom part of the rocket, known as the Super Heavy booster, being caught so cleanly on the first attempt seemed slim.

Prior to the launch, the SpaceX team said it would not be surprised if the booster was directed to land in the Gulf of Mexico instead.

You might hear all the above during the execution of starship booster capture. Maybe this is the first attempt the capture passed, but there is a decade of work behind it.

Let's dive into History first and get some perspective from the scientist who is working on mitigating climate change, According to Andrew Wilson, assistant professor in environmental management at Glasgow Caledonian University in Scotland. Historically, the space sector has been granted a lot of exemptions from different legislations, and, as a result, they have gotten away with doing what they want. Right now, the overall amount of greenhouse gas emissions from spaceflight is negligible, equivalent to 1% or 2% of the carbon footprint of aviation, which by itself makes up about 2.5% of overall global greenhouse gas emissions. However, the number of rocket launches has been rising steeply in recent years. Right now, the overall amount of greenhouse gas emissions from spaceflight is negligible, equivalent to 1% or 2% of the carbon footprint of aviation, which by itself makes up about 2.5% of overall global greenhouse gas emissions. However, the number of rocket launches has been rising steeply in recent years. According to astronomer and space age historian Jonathan McDowell, 2023 saw a record-breaking 223 attempted spaceflights worldwide. That's more than double the 85 attempts made in 2016. SpaceX alone launched a record 96 orbital rockets last year and aims for nearly 150 in 2024. SpaceX's bold ambitions are what worry scientists like Wilson. That's more than double the 85 attempts made in 2016. SpaceX alone launched a record 96 orbital rockets last year and aims for nearly 150 in 2024. SpaceX's bold ambitions are what worry scientists like Wilson.

The above thought is the perspective of one of the scientists. Let's decode it in the opposite way, Starship is a space transportation system consisting of two parts — the Starship spacecraft and the Super Heavy booster rocket. A booster is a powerful first-stage rocket engine designed to provide the initial thrust needed to lift a spacecraft off the ground and into space.

Boosters

Boosters are typically used to help heavy payloads overcome Earth's gravity during the early phases of launch. Once their fuel is depleted, boosters are thrown back to Earth — making them unusable for further future missions.?

But now, with SpaceX's latest breakthrough technology, it is possible to catch the booster and keep it for future use.

SpaceX built a 400-foot tall tower for catching the Super Heavy booster rocket once it is detached from the spacecraft. The Mechazilla tower, with its large mechanical arms known as 'chopsticks', is located at SpaceX's Starbase in Texas.

Space missions are costly as most rocket systems are expendable, that is, they can be used only once.?

Mechazilla cuts the cost in terms of both money and time. Engineers have been trying to design reusable systems for decades, and finally, the SpaceX engineers have done it.

Capex & Opex

Traditional rockets typically have high capital expenditures (CapEx) because a new rocket must be built for each launch. In contrast, Starship has lower CapEx because of its reusability, allowing the initial development and manufacturing costs to be distributed across multiple launches.

Operating expenses (OpEx) for conventional rockets are higher due to the costs involved in preparing each new rocket for launch, such as fuel, ground support, and crew. However, Starship's OpEx is expected to be lower since it can be reused. Refurbishing and readying a Starship for its next launch is anticipated to be much less expensive than building an entirely new rocket.

Reusability - Reducing Waste and Emissions

Traditionally rockets are discarded after a single launch, which results in a tremendous amount of waste and high source consumption to build new rockets for each mission. In contrast, Starship is designed to be reused multiple times, drastically reducing the need to manufacture new rockets for every flight. This reuse model is similar to that of commercial airlines, where the vehicle is turned around quickly and flown again.

Every time a rocket can be reused, it prevents tons of steel, aluminum, and composite materials from being discarded or manufactured anew, resulting in fewer emissions from production processes and raw material extraction. Reducing the production of new rockets also lowers the carbon footprint of each space mission.

Do you wonder how much carbon is being emitted at each time of manufacturing new rockets?

Furthermore, the rapid reuse of rockets like Starship can reduce the number of launches required to fulfill the same mission goals. For instance, launching a constellation of satellites or resupplying a space station could be done more efficiently with fewer overall flights, lowering the total emissions per mission.

Methane as a Cleaner Fuel

Starship’s Raptor engines use liquid methane (CH?) as a propellant, which is cleaner and more efficient than traditional rocket fuels like RP-1 (refined kerosene). Methane burns with fewer soot particles and produces less black carbon, which is one of the most concerning pollutants from rocket launches.

Black carbon is a form of particulate matter that can contribute to global warming, especially when released in the upper atmosphere, where it can remain for extended periods and absorb sunlight.

By choosing methane over kerosene, SpaceX is working to minimize these harmful emissions. While methane combustion still produces carbon dioxide (CO?), its lower soot production helps reduce the overall climate impact.

Additionally, methane is more efficient in terms of energy produced per unit of mass, meaning that Starship can carry heavier payloads while using less fuel per flight, which further reduces emissions per launch.

SpaceX also envisions producing methane sustainably on Mars through the Sabatier process, which involves reacting CO? from the atmosphere with water to generate methane and oxygen. If this system can be implemented on Earth, it could theoretically reduce the reliance on fossil-fuel-derived methane, enabling a more sustainable fuel cycle for space exploration.

Over to you

Despite these innovations, the environmental sustainability of rocket launches is not without challenges. Rocket emissions, particularly black carbon, released into the upper atmosphere have unique and complex environmental effects. Unlike emissions from planes or cars, which occur lower in the atmosphere and are more easily mitigated, rocket emissions at high altitudes can linger for longer periods, influencing the ozone layer and contributing to warming on a global scale.

Experts, like Dr. Eloise Marais, have noted that while methane is a cleaner fuel, the exact extent of black carbon emissions from liquid methane rockets is not yet fully understood, and more data is needed to assess their long-term impact.

Additionally, the Federal Aviation Administration (FAA) has raised concerns about the potential environmental impact of frequent launches, particularly in sensitive regions like Boca Chica, Texas, where SpaceX’s launch facility is located.

SpaceX’s Starship program, through its focus on reusability, cleaner fuels, and innovative booster recovery methods, represents a significant step forward in reducing the environmental impact of rocket launches.

While challenges remain—especially concerning high-altitude emissions—the program’s technological advancements offer promising pathways for both sustainable space exploration and contributions to climate change mitigation.

By making space more accessible and environmentally responsible, SpaceX is paving the way for new solutions to Earth’s environmental challenges, while simultaneously aiming for multi-planetary sustainability.