Don't confuse results with effort.
"Cancer" is a nebulous area. You can't really study "cancer". Cancer isn't a disease. It's a class of diseases characterized by a breakdown of your own cells' reproductive process. Not to mention, it's a breakdown that can just happen. You can take every precaution, avoid every carcinogen, and still get cancer. The biggest predictor to whether or not you will get cancer is time. The longer you live, the greater your chances.
And we might "get" cancer far more often than we realize. It's just that our bodies do have ways to excise cancer from our own bodies. It's just that sometimes, it's not enough.
And there is a lot of research that goes into cancer prevention and treatment. But it's not like one day we'll have the anti-cancer pill. That's just magical thinking.
Life extension research is also in a weird place. Because, like cancer, there isn't just one thing that ends our life. It's a host of things. And a lot of those things are being looked into. And we've already made amazing strides. We are able to get way more people to advanced ages than before. Prior to modernity, it was basically luck as to whether or not you'd make it to 60.
And I don't even know what you want to mean by "brain-computer" research. But I assume it would eventually involve fucking around with living brains. You absolutely cannot make a mistake there. You don't go poking around in the brains of healthy people unless you want to make them very unhealthy, very quickly.
So each of the things you've picked out are vague and/or fraught with their own perils.
Chucking a meat-filled metal tube at a space rock and getting the meat back is an objective with a clear goal.
And also, I'd like to point out, that failure was an option. Michael Collins was trained in everybody's job just in case he had to come back alone. During the first orbit, when he was out of contact with everybody for 48 minutes, he had no idea what he would find when he came back around. That and this was a process of years. The mission that landed on the moon was Apollo 11. Preceded by the Gemini program, whose main purpose was to lead into the Apollo program. 8 years for the singular goal of having a man go to the moon and return.
"Curing cancer" is not the same. "Brain research" is not the same. "Life extension" is not the same. Pick one thing. One simple goal. Not "cure cancer", but something like "make non-nauseating chemotherapy". Then dedicate 8 years to achieving that one task, no matter the cost. Which is something they do do. Any time you see something about "targeted cancer medications", that's to end-run around chemotherapy. Because chemotherapy is kind of like setting your house on fire to get rid of termites.