Physicists squibbed out how rocketing a Falcon 9 transforms the atmosphere

Physicists squibbed out how rocketing a Falcon 9 transforms the atmosphere ...

With the cost of launching a rocket into space declining, the number of rocket launches is steadily moving. Last year, governments and companies across the globe successfully launched 133 rockets into orbit, breaking a new high.

A catch is that breaking free from Earth''s gravity requires a rocket to release tremendous amounts of energy in a short period of time. In a peer-reviewed journal Physics of Fluids, a pair of scientists simulated the launch of a SpaceX Falcon 9 rocket blasting into space.

They found several reasons to be concerned.

The carbon footprint isn''''t the problem

Rockets aren''t responsible for putting too much carbon dioxide into the atmosphere. A typical launch uses about as much CO2 as a day-long commercial flight, which is in the hundreds of tons. That''s much more carbon than the average person will generate in their lifetime, but it''s a rounding error compared to the 900 million tons of CO2the aviation industry was spewing annually.

The whole story, however, is not important to a rocket''s carbon footprint. This is not the case for a rocket''s engineer. According to Ross, it''s crucial to distinguish between particles that are mostly alumina and black carbon. These particles increase sunlight and transform the atmosphere and circulation of the planet.

Scientists have limited knowledge of the total environmental implications of a rocket launch. According to Ross, the current level of data on rocket emissions does not provide enough information to fully assess the implications of rocket launches on the globe.

The potential of high carbon emissions in the atmosphere is uncertain.

The researchers behind the new research are bringing the problem into an even greater depth by modeling the exhaust from the nine nozzles of a Falcon 9 rocket as it enters space. These simulations combine data about the rocket and its propellant (RP-1) and equations that show how gases behave under various conditions. A result of some serious computing power, the researchers were able to understand how exhaust behaves following the exit of the nozzles at an angle of roughly 0.6 miles (1 km) in altitude.

The researchers compared the amount of exhaust released during one kilometer of upward travel through a certain area of the atmosphere (e.g. between 2 km and 2.99 km) with the properties of the atmosphere at that specific altitude. This technique was a somewhat awkward process because the physical and chemical composition of the atmosphere is different at different angles.

The amount of total exhaust was found to be "negligible" compared to the air around it even at high altitudes. That''s a surprise because the atmosphere is much less dense at higher altitudes. According to their estimates, the amount of exhaust released by a Falcon 9 as it travels between 70 and 70.99 km (roughly 43 miles) is only one-fourteenth the amount of mass found in one cubic kilometer (roughly.25 mi3) of air at that altitude. (This

Whatisn''tnegligible is the amount of CO2 that a Falcon 9 introduces into higher atmosphere as it passes through (represented by the dotted red line in this figure above)

And rocket exhaust contains more than carbon

"Perhaps even more crucially, the [amount of] carbon monoxide (CO) and water (H2O) [in rocket exhaust] are of a similar order as carbon dioxide," the authors argue. This is because there is hardly any carbon monoxide or water high in the atmosphere. "Therefore, these compounds emissions at high altitudes make a significant contribution to the existing, if any, trace amounts already present."

Water vapor is almost frozen at that altitude, but researchers have no idea where those ice crystals end up. Carbon monoxide (OH) helps to form even more CO2. Finally, researchers discovered that dangerous exhaust emissions calledthermal nitrogen oxides (NOx) can stick around for a long time before dispersing throughout the atmosphere, especially at lower altitudes.

The future is uncertain, but experts and regulators are paying their attention.

Some argue that rocket pollution isn''t an issue. "One of the reasons that people have used in the past was to argue that we don''t really need to pay attention to rockets or the space industry, or the space industry is small, and it will always be small," Ross said.

He doesn''t agree. "I think the recent developments we''ve seen demonstrate that space is entering this very rapid growth phase like aviation in the ''20s and ''30s."

The authors of the new study feel the same way. "We believe that rocket launches'' atmospheric pollution is fundamental and must be addressed appropriately as commercial space flights, in particular, are expected to increase in the near future," they write.

The problem of rocket pollution is slowly getting into a more clear focus, and it''s being taken seriously in high places. Later this year, the World Meteorological Organization and the UN Environmental Program will release a new report that outlines how rocket emissions deplete ozone. This is likely to be a major factor in future rocket designs.

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