The organic molecules in the Martian meteorite were not from aliens.

Image 1: "The Allan Hills 84001 meteorite courtesy of NASA/JSC/Stanford University. Credit: Courtesy of NASA/JSC/Stanford University" (ScitechDaily/The Search for Life on Mars: Organic Molecules in Martian Meteorite Not From Aliens.)

The organic molecules in the Martian meteorite were not from aliens. The fact is that proving the lifeform or fossil as extraterrestrial is not a very easy thing.  When we try to prove the origin of molecules or fossils there should be an environment where those samples would stay untouchable. 

The deep ice in polar ice caps might seem very promising. But in that environment, those samples are very easily polluted. When meteorite comes through the atmosphere it will heat. 

And when it touches the ice cap that temperature melts the ice. That thermal effect will activate bacteria and primitive algae in that ice. And some of those tiny organisms are searching for temperature. So the meteorite that comes from Mars is polluted by domestic organisms. And even if some procaryotes. 

Image 2) Planet Mars in natural color. (Wikipedia/Mars)

Which are the most primitive organisms on Earth traveled to the Earth from Mars they are hard to separate from domestic eucaryotes like cyanobacteria. For confirming the origin of the bacteria fossils the samples must be taken to Earth or some moon laboratory straight from Mars. That thing is necessary for keeping samples sterile. 

If there are some prokaryotic bacteria on Mars. That means those bacteria would be extremely small fossils. And the remaining metabolism of those hypothetical bacteria or their microscopic fossils uncovers their origin. The idea is that the metabolism forms chemicals that remain in those fossils or holes that were remaining of those hypothetical ancient bacteria. 

The theory of life on Mars goes like this. There was a short period in the history of that planet. When lifeforms could form. Those lifeforms would look similar to the cyanobacteria on Earth. But then meteorites or cosmic impact caused the planet Mars to lose its core and atmosphere. 

There is the possibility that those tiny lifeforms would remain active when the temperature of the surface decreased. But then the UV radiation whipped them out. This thing is the most common theory of the lifeforms of Mars. If those ancient lifeforms would somehow flow to Earth riding with some meteorite and remain active they are hard to separate from the domestic bacteria. 

There are needed DNA tests. When the DNA tests are made there must be confirmed Martian bacteria DNA or RNA for those tests. And UV radiation could destroy the entire genomes of those hypothetical bacteria. 

And there is the possibility that the remainings of the hypothetical Martian-origin bacteria. Like their genomes are destroyed by UV radiation. Of course, is the possibility that the impact that wiped out those organisms was not the last one. So if some bacteria came from Mars that bacteria could be a fossil. Or they could be vaporized while the meteorite flew to the sky by some cosmic impact. 

When the meteorite left Mars that thing was the drop of the melted material. And while the travel from Mars to Earth. It was under the influence of cosmic radiation. Also, the flow of the particles that came from the Sun terminated the organic material. That means that the alien bacteria could not even exist anymore in that meteorite even if there were the lifeforms on the red planet far away in history. 

https://scitechdaily.com/the-search-for-life-on-mars-organic-molecules-in-martian-meteorite-not-from-aliens/

Image 3) The advancing of the Image of Cydonian face. Images from the left: two first images. A and B  are from Viking.  Image C is The 2001 FaceA second "full-faced" image of the "Face" NASA/JPL MOC E03-00824. Note: the distinct "Feline" features on the right side. The erosion has destroyed the form of the face. And there is the small crater. So somebody might say, that could something whip that thing away in purpose. (Images by NASA)

Image 4)  The "Cydonian pyramids". : Pinterest

The alien story begins from here. The data is not confirmed. 

In some hypotheses, the (alien) civilizations would go interstellar travel only when they must do that thing. So if the hypothetical civilization would leave from the stars like Van Maanen 2. That thing means that those creatures would go on a one-way trip. 

When we are thinking about the colonization of the Milky Way we must understand one thing. That thing is not possible quite soon. If that project will someday start. The creatures who go on those journeys will never return. They would go on a one-way trip which takes even millenniums. 

Those creatures would travel in the form of genetic material. And during that journey, artificial intelligence would control the craft. When that craft will reach its target. The genetic material would transfer to cells. So those cells would be infected by the virus that transforms them into aliens. 

And things like the "face" of Mars (Image 2) and "Cydonian city" (Image 3) are bringing imaginational visions in the mid of people. There introduced a theory or hypothesis. That alien from some other solar system is behind those structures. And they would be created by some kind of robot. 

The theory is that the faces that might be lost are created by machines that are copying structures. Even if that thing would be true the alien would not necessarily use those structures. 

In some other vision, those structures came to NASA flight control accidentally. When some spy satellite used the frequency that the Viking probes used. The idea of the base where the Mars astronauts will use is taken from that theory. The idea is that the robots are making the base ready for astronauts before they will land on the red planet. 

https://scitechdaily.com/the-search-for-life-on-mars-organic-molecules-in-martian-meteorite-not-from-aliens/

https://en.wikipedia.org/wiki/Van_Maanen_2