NASA is constantly researching the possibility of sending humans into space with perfect nutrition. Chlorella has been at the top of this research list for over five decades. This is mainly a result of its perfect nutritional array including over 100 nutrients as well as 60% protein (more than double the content found in meat, fish or chicken). Another main reason is because of its fast/efficient growth capability. It even possesses the highest percentage of chlorophyll of any organism and is therefore very good at filtering carbon out of the air while in space.
Trying to send astronauts to the outer limits of the solar system is one of the greatest challenges in human history. One of the biggest obstacles in this quest is to provide the traveler with enough nutrition to sustain such a long amount of time in isolation.
There are hundreds of articles listed on NASA 's website dealing with chlorella. Most of these are in depth reports showing how chlorella responds to changes in conditions that would be encountered while in space. Three main changes being
1) Loss of gravity
2) Variations in light
3) Variations in air quality
It is fascinating to see that our country's space program has dedicated countless hours to such a seemingly insignificant microalgae that has been in existence for a billion years. Chlorella was only discovered a little over a century ago; this means NASA has been researching this super food for half the time mankind has known of its existance
The vast majority of these reports are either classified or not available online so here are some links to various NASA reports dealing with Chlorella.