Is There Life On Mars ?

Probably Mars had life

Scientists at NASA, ESA(European Space Agency) and some other organizations now claiming Mars had life, as per new study reports.

We know, life originated on Earth around 3.5-4 billion years ago, but scientists now theorizes that life on Mars may had began before Earth, around 4.48 billion years ago. The interior surface of Mars had water, which later came on surface to create oceans, by meteor showers, where first life could have thrived. Western University's Desmond Moser said, "Giant meteorite impacts on Mars between 4.2-3.5 bliion years ago may have accelerated the release of early waters from interior of the planet setting life-forming stages."
Some craters and landscapes on Mars have been found, that carries the hard evidences that water flowed over there once.

In 1993, at NASA, scientist David McKay and his team discovered a Martian rock(from a Martian Meteorite that fell on Earth), from Antarctica, called ALH84001(which is 4 pounds), which had a peculiar chemical makeup. He said that it had organic molecules Polycyclic Aromatic Hydrocarbon(PAH), which's produced by biological activities. The rock contained a combination of minerals and carbon compounds, which are created by microbes on Earth. It also had crystals of magnetic iron oxide, called magnetite, which family of Magnetotactic bacteria species produce(on Earth) for navigation. The rock also had chains of carbonate globules(composed of siderite, magnesite, magnetite crystals, pyrrhotite and gneigite) that bore a striking resemblance to chains that some bacteria formed on Earth and most important, his report told that there were bacterial blobs(shaped wormly) on the meteorite which looked like a dead colony of bacteria.
This could be the proof that Mars had life once, it's a solid evidence, as NASA claimed that time.

But as soon as his team did it, some researchers opposed his ideas. They said the PAH can also be formed through inorganic process and doesn't stands as a strong evidence of past life on Mars. Then, they also told that bacterial blobs in that meteorite were smaller than any bacteria seen on Earth. They were too smaller to be free living organisms because they couldn't have held all the proteins, DNA and other molecules necessary for even the simplest metabolic processes. So, the bacterial blobs were rejected as being created due to inorganic processes. But David then came with a point, that they could be smaller pieces of large organisms. But half of his colleagues didn't pay heed.
Then, he said that the complex carbonate globules and magnetite crystals can't be produced inorganically. But in 2001, his brother Gordon McKay and his team showed that those can also be produced inorganically. In the lab, Gordon and his team created a simulating environment(that once the meteor faced on Mars) and inorganically managed to cook up batch of magnetite grains--similar to meteor's ones. They also incorporated the magnetite grains into balls of carbonate, and finally created complex globules of carbonate chemically. So, as a result, around, more than half of the NASA scientists dismissed the theory of David McKay about past microbial life on Mars. But David kept on insisting that Gordon's experiment didn't accurately described the process of formation of bacterial magnetite crystal chains and carbonate globules on meteorite and aren't sufficient similar to meteor's ones, but half of his colleagues didn't pay heed.
Additionally, NASA scientist Chris McKay said about David's research, "However, magnetite crystals from Mars might more persuasively indicated life if they had been found in string-of-pearl formations as we see on Earth. But, the meteorite's magnetite crystals weren't in that accurate formation. And moreover, shockwaves created during meteor blasts can also generate such magnetite crystals in it. But we appreciate David's works."
Meanwhile, in 1999, while David and his team was being questioned about the size(they were too small to be bacteria) of bacterial blobs, a biology workshop, supporting the theory of David and his team, claimed that those bacteria could've been primitive based on single polymer system. They could've been RNA(ribonucleic acid) based life with ribozymes(catalytic RNA), which can act like large ribosomes of modern bacterial cells(who are DNA based lifeforms) for cell replication. Cells having ribozymes(means RNA based life) won't needed proteins and DNA. They totally gave a hypothesis on a nanobacteria, the bridge between primitive nano-life forms and modern bacteria. According to them, these nanobacteria can be sized upto 50 nm(nanometers), similar to the size of bacterial blobs found on meteorite. But, the scientific community had a debate in that time about RNA based life. It is doubted that whether such life ever thrived, but recently(21st century), biologists are finding evidences of possible RNA based life, as they are discovering some nanobacteria (50-200 nm) and making theories that may had evolved to today's DNA-based life.
However, the workshop didn't wanted to go further on RNA-based life researches. They just tried to support David's researches through several logics like;
1) Bacterial cells can shrink after death.
2) The discovered mineralized fossils could be remains of fragments of much larger organisms.
3) Those organisms could've been pathogens or symbiotes which depend on host.
4) They could live in consortia of smaller cells unable to survive independently.
5) They could've been based on different biological system, unknown to us(RNA-based world).