The humble element oxygen sustains life on our planet in more ways than one. Three oxygen atoms can bond to form an ozone molecule.  At roughly 20-25 kilometres above the sea level, in the layer of atmosphere we call the stratosphere, these molecules connect with each other forming a protective umbrella over us. It is called the ‘ozone layer’. The Ozone layer absorbs UV radiation from the sun, acting as a sunscreen for life on Earth.


For decades there have been concerns about the depletion of this protective layer. Researches point out that potentially harmful UV-B radiations might already be penetrating to ecologically significant depths of our marine environments. Marine planktons create about half the atmosphere's oxygen; and the nutrients and biomass they produce sustain life and balance of our oceans. Thanks to phytoplankton, our oceans act as a major carbon sink, mitigating the effects of greenhouse gases. If UV radiation reaches a level significant enough to influence the survival and distribution of marine plankton in near-surface waters, then there will be detrimental consequences to both terrestrial and marine ecosystems. Ozone depletion directly affects our health by causing skin cancers, retinal degeneration, cataract formation and immune system disorders. In high doses, UV-B radiation can change the molecular chemistry of our DNA.


Ozone depletion is caused by human-made chemicals, and will continue to be a threat until we are successful in phasing out the compounds responsible for it. Initially, scientists were oblivious to the far reaching consequences of chemicals like chlorofluorocarbons(CFC),  which had found extensive use in industrial and household sectors. Many refrigerators, air conditioners and foam-blowing-equipments are used to emit dangerous levels of chlorine gas into the atmosphere. The alarming fact is that chlorine compounds, bromine compounds and other chemicals that we release into the atmosphere can remain in the troposphere for decades, effectively forming long-term reservoirs of these dangerous chemicals. When these chemicals reach the upper stratosphere, ultraviolet light causes CFCs to break apart, releasing chlorine. Acting as a catalyst, this harmful element is not used up in the chemical reaction that breaks down the ozone molecule. Instead, being a catalyst means that a single chlorine atom can destroy thousands of ozone molecules. Once triggered, ozone destruction is a chain reaction that goes on until the ozone-destroying forms of chlorine are dispersed as the air from the surrounding latitudes mixes into the affected region.


What this means is that ozone layer recovery is a very slow, long process. In fact the monitoring bodies and the WHO are not expecting a full recovery until the year 2050. That is, if the world nations care enough to abide by the Montreal Protocol.  The United Nations established the Montreal Protocol in 1987, to regulate the quantities of harmful gases in our atmosphere.  The treaty has had the privilege of universal ratification and since the treaty there has been reduction in the ozone depletion process.  The controlled substances list in the treaty is updated to reflect the results of current scientific monitoring and research. This is a hopeful and promising scenario where the world nations join hands today, to work towards future environmental goals.


Recently, researchers have detected an increase in CFC-11 emissions, majorly over the Asian continent - possibly the result of unauthorized industrial production, going against the Montreal Protocol.  What is more worrisome is the ‘rocket race culture’ that has now been sometime in the making. SpaceX recently made the headlines when its flagship rocket Falcon 9, deployed 143 satellites into orbit. Studies conducted as far back as 2009 clearly state the perils that unregulated rocket launches could cause to our ozone layer.  


If left unchecked, rocket launches could result in more ozone destruction than was ever realized by CFCs. Rocket combustion products are the only human sources of ozone-destroying compounds injected directly into the stratosphere. This means that the destruction they cause is more direct and immediate.  Microscopic particles, including chlorine, black carbon and aluminium oxide, emitted by rocket engines, act as catalysts providing chemically active surfaces that facilitate ozone destruction. To make matters worse, the particles emitted directly into the stratosphere have a tendency to accumulate there. There they absorb and reflect solar energy, changing the flow of radiation in the atmosphere, heating the stratosphere and cooling the surface, respectively. This ‘radiative forcing’, adversely affects Earth’s climate patterns and accelerates ozone destruction.


As the rocket launch market grows, so does the need for stringent regulatory measures to safeguard our ozone layer.  CFCs and HCFCs, when discovered, were deemed the miracle chemicals that found a myriad of uses in many different industries.  For decades we let these harmful chemicals accumulate in our atmosphere.  The harm caused by frequent rocket combustion materials being injected directly into the stratosphere might be even more catastrophic. It’s high time the space industry was made part of the Montreal Protocol.  Enticing might be the call of barren planets light-years away, but our allegiance first and foremost lies with the planet we call home.