Hydrogen Powered Rocket Engines That Don't Hurt the Environment

A liquid-rocket propulsion system, according to Encyclopædia Britannica, is composed of the "engine, fuel tanks and vehicle structure with which to hold these parts in place and connect to payload and launch pad or vehicle." The lightweight fuel tanks typically operate at a low pressure. According to Britannica, propellants such as hydrogen and oxygen are gaseous at ambient temperatures. To remain in the liquid state, the materials must be kept extremely cold.

Hydrogen Peroxide

• According to Tecnologia Aeroespacial Mexicana (TAM), hydrogen peroxide (H2O2) passes through a catalyst pack and decomposes into superheated oxygen. According to TAM, you get 5,000 times the volume of liquid injected at the catalyst when it's expelled through the nozzle. The process is flameless.

  The process uses an 80 percent to 98 percent concentration of hydrogen peroxide. Since this is the only propellant used, it falls within the monopropellant liquid rocket fuel classification.

  Although the fuel produces oxidation burns on unprotected skins and eyes, hydrogen peroxide is nontoxic and, when uncontaminated, nonvolatile. It's stable when properly stored and ventilated.

Hydrogen & Oxygen

• According to Encyclopædia Britannica, each of the space shuttle's main engines uses liquid oxygen (LO2) and liquid hydrogen (LH2) propellants. The National Aeronautics and Space Administration (NASA) states that the orbiter's fuel cells use the two liquids to "produce electrical power through a process best described as electrolysis in reverse. Liquid hydrogen and oxygen burn clean, leaving a by-product of water vapor."

  The liquid hydrogen and oxygen must be stored at around 20 degrees above absolute zero to remain in a liquid state. According to NASA, using hydrogen permits a mission to launch with a smaller quantity of propellant and in a smaller vehicle. If the mission calls for a larger payload, it would still require less propellant than conventional propellants.

  The flame produced by the burning of hydrogen and oxygen is nearly invisible to human eyes. Leicester University's Space Research Centre's director, Professor George Fraser, told BBC News that the exhaust gas resulting from the hydrogen and oxygen mixture consists of water vapor and is harmless to the atmosphere.

Controversy

• Professor Fraser told BBC News, "As a shuttle launches, a 'cloud' becomes visible, which contains solid rocket booster exhaust products, either dissolved or as particles in the water vapor released by the main engines." According to Fraser, the surrounding area gets acidic deposits from hydrochloric acid formed in the cloud. The dispersal distance is dependent on the wind conditions.

  According to BBC News, a 1993 NASA technical manual stated that the area surrounding Kennedy Space Center has a reduced number of plant species and total cover. Acidic deposits can, according to the manual, impact nearby water lagoons and their wildlife.

  According to the BBC News article, the manual states, "These impacts on wildlife appear minimal and manageable."