Exist aliens? Even if extraterrestrial life has not been found, it is still possible. Astrobiologists at NASA like Lindsay Hays are working to find the answer to one of humanity's most important questions: Is there life elsewhere in the universe?

NASA's Scientists : Our understanding of livable habitats keeps growing. We've only just started searching beyond Earth. Four landers and five rovers have been deployed by NASA to Mars. Additionally, incredible cameras have been added to orbiters so they may capture images of the whole surface of the Red Planet. But we've only really looked at a small portion of Mars. And that is just one of the promising bodies in our solar system to search for life.

The frozen worlds of the outer solar system, such as Jupiter's Europa and Saturn's Enceladus, appear to have potentially habitable subsurface oceans. And only that is contained within our solar system. The more exoplanets we discover orbiting other stars, the more we discover about the many settings that potentially support life.

We are unable to definitively state that aliens exist at this time. "The universe is a pretty big place," said Carl Sagan. If it's just the two of us, it seems like a terrible waste of room. NASA will therefore keep looking.

NASA's Scientist statement Highlights :

1) NASA doesn't deny or confirm that aliens exist

2) However, NASA said it will keep on looking for it

3) There are 2 - 5 % of cases about UFO sightings are mysterious and cannot find what really happend

Others dismiss the notion outright, while still others will hauntingly recount their own experiences of extraterrestrial probings after taking a leisurely evening stroll across the fields of a small town in America. Some people claim that it is evident that we are not alone. But these days, disbelief is tougher to maintain with everything from increasingly odd news from increasingly reliable sources to elementary mathematical probability showing the likelihood of alien life. The following instances may well have an effect on your opinions, regardless of what they are : 
1. In a game of numbers, the likelihood that aliens exist is high.
2. Hundreds of possibly habitable planets are already known to us.
3. Life has been discovered on Earth in places where we had no reason to believe it could exist 
4. The life that exists may not be intelligent life
5. Intelligent lifeforms may exist in environments that make communication challenging 
6. We may be attempting to communicate with one another through diametrically opposed means 
7. Given the distance between stars and Earth, it may take a message from extraterrestrials thousands of years to reach us. 
8. For contact to occur, both our civilization and the alien civilization must have existed at the same time.
9. We may never be able to travel across the solar system in long-distance space.
10) Also we are going to find something which is unpredictable

And this is one of the most craziest factor , Whether humans are able to survive on Mars then Humans start migrate to  the Mars and continue their lifes , It would be the starting point of new civilization, when the first human child born on Mars then it is considered as a alien for earth, so we are not going to find the aliens we are going to create it 
What is your statement about this craziest factor? mention on your comments....