Rocket Science: A Tug Between Sustainability and Space Travel [edit]
The future of space travel is going green, but is that good enough?
3…2…1…
Blast off!
A rush of steam clouds swirl around a rocket as the engines fire to full power. It accelerates into the atmosphere like a comet but with a streak of flames. Amidst its journey into space and beyond, the rocket sprays an abundance of pollution straight into the sky. Its carbon footprint from one launch compares to the emissions 65 vehicles will produce in a year, but this would be something that we would not immediately think about. I, too, dream about how far we can go and when we can get there. But in this perfect reality, I failed to realize that the continued neglect for the climate crisis — even for rockets — will turn our quest for the cosmos into a dire search for a new home.
Rockets are no less exempt from air pollution than a plane. (Speaking of, planes need air to fly and wings to lift; rockets do not need either and can blast into space.) Rockets may contribute only a small percentage to the total carbon emissions, but that doesn’t mean they are sustainable. A passenger in a long plane ride may have a carbon footprint of two or three tons. Take them on a rocket, and their footprint shoots up to 300 tons. That doesn’t even consider how rockets deposit their emissions straight into the upper atmosphere, where those gases can claim home for up to three years.
Most space agencies veered their operations toward better environmental consciousness. NASA has its own sustainability base dedicated to its green mission. Two years ago, the European Space Agency contracted $35 million towards the Themis program, which will be a reusable first-stage rocket. About 5300 miles over, the Japan Aerospace Exploration Agency has also been setting goals for minimizing CO2 emissions and electricity consumption.
These efforts all have different standards for defining sustainability. I have realized that their sustainability comes in gradients. One end is practical (like recycling a plastic water bottle), and the other systemic (having a reusable water bottle). Rockets are the same way with their setup. Germany’s Johann Schmidlap 16th century “step rocket” remains the gold standard for rockets today. The process calls for stages: the first stage for blast-off and the second stage for when the larger rocket disbands and the smaller rocket flies to higher altitudes. Sometimes just the booster engine is reusable. Maybe even the first stage. But when the launch is reusable, that’s when a rocket is “fully” sustainable, at least in hardware. For the sake of this blog, a reusable rocket is capable of repeated flights and manages to complete several missions (not just the test runs). Rockets are more complicated than water bottles, so to make them reusable, they would have to survive the reentry environment; for any rocket ready for a journey into space and back, it’ll need thermal protection and a robust structure. On top of that, a rocket isn’t so reusable if it needs a three-month repair after each mission.
Notable space explorers are already pumping sustainability into their rockets. The pioneer that started it all is hands-down NASA’s Space Shuttle, the world’s first reusable spacecraft. Well…I should say partially reusable because the external fuel tank was not reusable (it burns up in the atmosphere). Over at Space X, the Falcon 9 (a two-stage rocket) is the first orbital-class reusable rocket. Its fuel isn’t as environmentally friendly, rocket grade kerosene being the culprit, but for a powerhouse rocket that is orbital class, one cannot sacrifice all performance for sustainability. Blue Origin’s New Shepard is like the poster child for sustainable rockets. The New Shepard has landing gear, is almost completely comprised of reusable material, and runs on liquid oxygen and hydrogen, with its only emission being water vapor.
It may be hard to believe, but rocketry actually started with water vapor. Back in 400 B.C., Archytas had his wooden pigeon (more or less a sphere) set atop a bowl with water and a fire underneath. Steam traveled through the pipes connecting the bird to the water to give it a spin. Eventually, the steam would propel the bird to fly, and that’s essentially all a rocket does. The Chinese introduced gunpowder rockets to warfare in 1232 during the Battle of Kai-Keng against the Mongols. Described as “arrows of flying fire,” rocketry would later be on Europe’s radar. In 1898, Russian school teacher Konstantin Tsiolkovsky proposed using liquid rocket fuel for better range. Such a move called for fuel tanks, a combustion chamber, and turbines, all ambitious efforts at the time, especially for a rocket. In the early 20th century, American Robert H. Goddard took on the challenge and achieved the first successful rocket flight with liquid-only propellant. (He used liquid oxygen and gasoline.)
The standard for rocket fuel in the 20th century consisted primarily of active chemicals — corrosive, flammable, toxic chemicals. As dangerous as they are to us and the environment, they make for undeniable efficiency, so shifting a rocket’s trajectory from climate devastation to climate preservation takes sacrifice. It’s calling space agencies and companies to forgo flight efficiency in search for a cleaner solution. For large-scale space missions, switching to something like liquid oxygen and hydrogen isn’t so simple. Nonetheless, carbon emissions aren’t the only air pollution to be concerned about.
Climate change has gained the megaphone it deserves to impact how we evolve technology around the environment. Sustainability entering space travel is a sign of progress in tackling the climate crisis at the root cause. Mother Earth has already been through enough; let’s not add rocketry to her headaches.
Updated: October 18, 2022
