The National Aeronautics and Space Administration (NASA) is the United States government agency that is responsible for the civilian space program as well as for aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.
Many microbes (such as bacteria and yeast) maintain the basic functions of life, such as nutrient consumption, internal chemical regulation, waste removal, reaction to external stimuli and reproduction. They definitely fit the scientific definition of life. Simpler things, such as viruses, do not eat nor reproduce on their own. Whether or not they are "alive" has been subject to debate for quite some time. Microbes don't have brains the way humans do, so they can't truly about what they are doing. Instead, it might be best to think of them as little pre-programmed machines. They react automatically to certain external cues based on the way they are constructed. For example, if there is a sudden increase in the salt levels (sodium and chloride ions) in their surrounding environment, these ions will diffuse into the cell and cause their cytoplasm to become more saline. Certain parts of the cell's organelles will be designed to react automatically to the increase in salinity. For example, it might set off a chain of chemical signals inside the cell which cause it to move away from the source of the salt (if levels rise too high to control via metabolism).
There is no evidence for visits of intelligent aliens to Earth, either now or in the past. The are many claims concerning UFOs and aliens, but no evidence to support these claims. The photos that are posted on the Internet are mostly fakes, and no one has ever produced an artifact or any other tangible scientific evidence of UFOs or aliens. One of strongest cases against the reality of these claims is that the group of people who spend the most time observing the sky are amateur astronomers, and they don’t report UFO sightings. If there were any evidence of aliens, astrobiologists would be among to first to hail such a discovery and analyze the data. However, there is no evidence that withstands scientific investigation. If you are still interested, you can use the search engine to find posted answers to specific questions about aliens and UFOs.
The discovery of life beyond Earth is one of the ultimate goals of astrobiology, but so far there is no convincing evidence of life. Today, astrobiologists are mostly concentrating their research on understanding Earth life, including its origin and range of habitable environments, and on determining if habitable environments exist beyond Earth (on Mars, for example). There have been very few actual searches as yet for life on other worlds.