Besides greenhouse gas pollution, kerosene-fueled rockets transport large amounts of black carbon, also known as soot, into the upper layers of the atmosphere. There, it remains for a long time, creating an umbrella that may add to global warming. Besides greenhouse gas pollution, kerosene-fueled rockets transport large amounts of black carbon, also known as soot, into the upper layers of the atmosphere. There, it remains for a long time, creating an umbrella that may add to global warming. Ross estimates that rocket launches around the world inject 10 gigagrams, or 11,000 tons, of soot and alumina particles into the atmosphere each year.
Rockets emit a variety of substances depending on their propellant. Some, like liquid hydrogen and oxygen (H2/O2) are very clean, emitting mainly water (H2O) and some nitric oxide (NO), which is produced by the heat of combustion. Others, like aluminum/ammonium perchlorate (or “Solid Rocket Motors”, SRMs) release hydrochloric acid (HCl) and alumina (Al2O3) particles. Rockets that use hydrazine (N2H4) and nitrogen tetroxide (N2O4) (sometimes called “hypergolic”, because these chemicals spontaneously ignite on contact) produce large quantities of nitrogen oxides, which can further react with water vapor and sulfate in the atmosphere to form small particles containing nitric acid. Kerosene rockets (essentially “aircraft fuel”) produce CO2 and black carbon (“soot”), which are climate-active gases (meaning that they absorb infrared or visible light, heating the surrounding air).
There is a new type of propellant called “hybrid” that is being used by some private companies. Hybrids are a mixture of a liquid oxidizer, nitrous oxide (N2O), and solid synthetic rubber (butadiene) that, when burned in the oxygen-poor environment of the upper atmosphere produce CO2 and large amounts of soot and probably large amounts of nitric oxides (although there are no measurements in these plumes to verify the presence of NOx).
The Chairman of the Indian Space Research Organization, K. Shivan has informed that the Indian space rockets are ready to go green as the space agency has been working to replace its existing hazardous fuels for its satellites and rockets.
ISRO Chief also informed that the space agency has been looking at green propulsion through hydrogen peroxide in its rocket propulsion through hydrogen peroxide in its rocket that will take Indians into space under its ambitious ‘Gaganyan’ mission. He further added that since humans will be inside the rocket, there should only be non-hazardous fuel to power the human space mission’s rocket.
The space agency has also been looking at the rocket engines that are powered by hydrogen peroxide as a bi-propellant or as a mono-propellant along with ethanol. It has also been developing another green fuel- LOX/Methane-where liquid oxygen will work as oxidizer and methane as fuel.
This propellent also has advantages in terms of storability, specific impulse, cost, and low toxicity. As per the ISRO Chief, the space agency has also been looking to replace its existing liquid engine fuels with environment-friendly fuel-powered ones. ISROSENE has been developed by the space agency which is a rocket-grade version of Kerosene. It will be an alternative to the conventional hydrazine rocket fuel.
While talking about powering the satellites, ISRO Chief informed that the space agency has been working towards lightweight electrical propulsion in place of the chemical fuel.
Currently, ISRO can put into orbit communication satellites that weigh up to four tonnes with its rockets. Satellites over four tonnes are being orbited using Ariane rocket of Arianespace, a European Space Agency.