This year marks 46 years since Neil Armstrong became the first person to walk on the moon . In all , 12 American astronauts have walked on the moon , the last - Eugene Cernan and Harrison Schmitt - doing so in 1972 . Enthusiasm for space travel has always decreased and increased . In 2010 , President Barack Obama cut funds for a NASA mission that would have put humans back on the moon by 2020 . " I understand that some believe that we should attempt a return to the surface of the moon first , as previously planned . But I just have to say here : We've been there before , " Obama said . NASA Administrator Charles Bolden has also thrown cold water on the idea of a return mission to the moon . But others believe there are benefits to going back to the moon . " It's the closest body to us , making it the least challenging to explore of all the planets , moons and asteroids in our solar system , " wrote Gene R. Grush , from NASA Johnson Space Center . " It's an opportunity to establish a permanent presence off Earth - a moon base for scientists or a colony for all of humanity . " " There is a lot of good science on the moon that we've only scratched the surface on , " said former astronaut Tom Jones . Richard Vondrak , from NASA's Goddard Space Flight Center , agrees , saying , " Astronauts can accomplish scientific exploration that is beyond the capability of robotic explorers . " And then there's the private business . In the last few years , several private companies - including Elon Musk's SpaceX - have launched rockets of their own , ending the national control over space flight . NASA is even considering a partnership with SpaceX , and Musk has said that if demand to go to the moon exists , his company will help fill it . Meanwhile , Buzz Aldrin , the second person to walk on the moon , believes that there's a much better target for exploration : Mars . " We've done the moon - we understand it better than anything else , " Aldrin said . " We've got to start thinking of long-term investments . " Richard Vondrak may support that   _   .
we have had a full understanding of the moon going back to the moon is a short-term investment we cannot merely rely on robots to explore the moon it is a waste of money to put humans back on the moon
Question: This year marks 46 years since Neil Armstrong became the first person to walk on the moon . In all , 12 American astronauts have walked on the moon , the last - Eugene Cernan and Harrison Schmitt - doing so in 1972 . Enthusiasm for space travel has always decreased and increased . In 2010 , President Barack Obama cut funds for a NASA mission that would have put humans back on the moon by 2020 . " I understand that some believe that we should attempt a return to the surface of the moon first , as previously planned . But I just have to say here : We've been there before , " Obama said . NASA Administrator Charles Bolden has also thrown cold water on the idea of a return mission to the moon . But others believe there are benefits to going back to the moon . " It's the closest body to us , making it the least challenging to explore of all the planets , moons and asteroids in our solar system , " wrote Gene R. Grush , from NASA Johnson Space Center . " It's an opportunity to establish a permanent presence off Earth - a moon base for scientists or a colony for all of humanity . " " There is a lot of good science on the moon that we've only scratched the surface on , " said former astronaut Tom Jones . Richard Vondrak , from NASA's Goddard Space Flight Center , agrees , saying , " Astronauts can accomplish scientific exploration that is beyond the capability of robotic explorers . " And then there's the private business . In the last few years , several private companies - including Elon Musk's SpaceX - have launched rockets of their own , ending the national control over space flight . NASA is even considering a partnership with SpaceX , and Musk has said that if demand to go to the moon exists , his company will help fill it . Meanwhile , Buzz Aldrin , the second person to walk on the moon , believes that there's a much better target for exploration : Mars . " We've done the moon - we understand it better than anything else , " Aldrin said . " We've got to start thinking of long-term investments . " Richard Vondrak may support that   _   .
A. we have had a full understanding of the moon
B. going back to the moon is a short-term investment
C. we cannot merely rely on robots to explore the moon
D. it is a waste of money to put humans back on the moon
Answer: