Rocket launches are an impressive culmination of human ingenuity as they push us into the future, but there is growing concern that not enough research has been done on their impact on the environment.
While some may be worried about potential greenhouse gas emissions, that’s not the main issue. Instead it is about depletion of ozone and the possible effects on our upper atmosphere, specifically the stratosphere, along with concerns about toxic fuels.
The problem flew under the radar, according to Martin Ross, an atmospheric scientist at The Aerospace Corporation, as people still think of rocket launches as rare.
But the time has come to face the fact that we may be entering an explosive era, he said.
“One of the arguments people have used in the past has been to say that we don’t really have to pay attention to rockets or space industry, or the space industry is small, and it will always be small,” Ross said.
“But I think the developments we’ve seen over the past few years show that … space is entering this very rapid growth phase, as aircraft have seen in the 20s and 30s.”
Black soot in the atmosphere
The stratosphere is a major weather driver for Earth’s systems, and here are some particles of rocket launches coming to an end.
The ozone layer, which helps protect us from the sun’s harmful ultraviolet rays, is also found in the stratosphere. In 1990, the Montreal Protocol was signed into law, banning harmful ozone substances, such as chlorofluorocarbons (CFCs), used in refrigerators and air conditioners, after it was revealed that the ozone layer had been removed from these chemicals. While the protocol concerned airlines, no mention was made of the aerospace industry.
But now some industry experts are worried that without oversight, we could have a problem.
There are various types of rocket fuses. Some, such as liquid oxygen and liquid hydrogen, produce mainly water vapor and have little environmental impact. These have been used in past ferries and even in the Saturn vehicles of the Apollo era.
Then there are those that produce alumina particles in the stratosphere, such as those in solid rocket accelerators, which were also used in past ferries, and are still used today by some launch companies.
Finally there are those that deposit black soot into the stratosphere, such as kerosene used in SpaceX’s Falcon 9 rockets and the Russian Soyuz.
It is the alumina and the black soot that are of most concern to experts.
“The atmosphere is complex,” said Jessica Dallas, a doctoral student at the Australian Center for Research in Space Engineering, in New South Wales. “We don’t have a complete understanding of atmospheric circulation and how all the mechanisms in the atmosphere actually work. And so that means we also don’t have a good idea of what happens when we inject these particles into the stratosphere.”
Dallas, who has written a comprehensive analysis of rocket fuse research, said she is concerned that there are no studies on how these particles interact in our atmosphere.
“Things tend to stay in the stratosphere for a long time, because it’s actually a very low mix [lower in the atmosphere], “she said.
“So you have black particles deposited in the stratosphere and then they stay in the stratosphere for three or four years … while with the alumina particles, they stay a little bit more locally because they’re bigger and heavier.”
Dawn of the new space age
Although experts say these rocket emissions are not an urgent issue right now, they are worried they will become one as the industry grows.
Launches into space are extremely rare: In 2016, there were about 80; in 2018, there were about 111, marking the first time since 1990 that there have been more than 100 launches. Since then, there have been close to 100 launches each year, and by April 20 there were already 30 launches this year, only half from the United States.
And there seems to be no indication that it has slowed down. On the contrary: with more and more countries getting involved in the “new space race,” smaller and cheaper satellites and NASA and commercial entities like SpaceX and Blue Origin looking at the moon and possibly Mars, are likely to grow launches.
In 2018 report from The Aerospace Corporation’s Center for Space Policy and Strategy, the authors compared the potential of atmospheric rocket emissions to that of orbital space debris – another problem that was not addressed when it was small half a century ago. Today worn-out rocket engines, decaying satellites or debris due to collisions are a threat to satellites and even the International Space Station. Several space agencies, including NASA and the European Space Agency, as well as private companies, are trying to develop ways to either collect it or mitigate it.
“If the potential magnitude of the space debris problem was recognized early in the space era, and coordinated international actions were taken at the time to address it, space debris may not have become the significant risk we face today,” the authors wrote.
“Today’s launch vehicle emissions present a distinct eoon of the problem of space debris.”
Develop cleaner fuels
In addition to the atmospheric effects, there is also the danger to the environment here on Earth.
Producing certain fuels, such as hydrazine used primarily in satellites, is highly toxic and carcinogenic. There is also a risk of spills. But some companies are trying to develop a fuel that may not only be less toxic here on Earth, but also in the atmosphere.
Tomislav Friscic, a professor in the chemistry department at McGill, is developing a new type of fuse that can be used for orbiting satellites that do not use hydrazine. Instead it is a metal-organic framework (MOF), where molecules form a literal framework.
“Because this frame is full of holes, and you can put things in them, that means you have material that you can modify on a few levels,” Frscic said. “You can insert high-energy components into them to increase energy density … and produce more responsive or possibly less responsive material if necessary.”
And a lot of Canadian research is going on on “greener” fuel, including companies in Quebec like Advanced Chemical Synthesis and Manufacturing (ACSYNAM) and Reaction Dynamics.
“My vision of how things will be is that we are no longer limited by the chemical limitations we have,” said Cristina Mottillo, co-founder of ACSYNAM. “My vision is that … we can actually learn more about how to unlock the chemical energy in the new fuse candidates … versus simply finding chemicals from the periodic table that have the necessary chemical energy.”
But even those agencies or companies launching today are looking for better options.
The SpaceX spacecraft, which CEO Elon Musk hopes will someday transport humans to the moon or Mars, is in its testing phase, but unlike its Falcon 9 rocket, it uses methane and liquid oxygen, which burns cleaner compared to some of the other fuses available. . And in 2019, NASA did its own test on greener fuel.
Although the good news is that investigations are underway, more players are needed around the world, Dallas said.
“There is a lack of such international cooperation. We need to start considering all the launches that are happening worldwide, because it’s not just about the United States. There are India and China, and there are so many more launches everywhere.”