It may sound strange, but it is true that scientists are quite concerned about bacteria from Earth reaching to Mars through probes landing on the Red Planet.

NASA unveiled about these organisms as, "have the potential to contaminate other celestial bodies, making it difficult for scientists to determine whether a life form existed on another planet or was introduced there by explorers".

It has become vital to reduce their presence and that is possible by knowing which organisms can survive the flight. Some studies reveal about how certain microbes are able to survive in interplanetary journey and tougher than others.

NASA found spore-forming bacteria to be the one posing maximum risk. They have the ability to survive certain sterilization procedures as well as can withstand the harsh environments of outer space. Spores from Bacillus pumilus SAFR-032 are able to restrict the techniques used to clean spacecraft like peroxide treatment and ultraviolet radiation.

These spores were able to survive 30 minutes in a simulated Martian environment. Another test was carried out in space, where spores were exposed to outer space for 18 months aboard the European Technology Exposure Facility (EuTEF).

Kasthuri J. Venkateswaran, a researcher at NASA's Jet Propulsion Laboratory and co-author of three papers said some of the spores were able to survive for 18 months. One more experiment was carried out on the spores of Bacillus pumilus SAFR-032 and other spore-forming bacteria called Bacillus subtilis 168.

The spores were dried on pieces of spacecraft and were kept in vacuum of space for 1.5 years. Most of the spores were not able to survive, but when the UV rays were filtered out and the samples kept in dark then 50% or more of the spores were able to survive. All the three experiments present a picture that spores could survive a trip on spacecraft to Mars if they are sheltered against solar radiation.