Developing a new drug, exploring space or mapping the human brain can cost millions of dollars.
But in recent years, there's been a decrease in federal funding for these kinds of projects and more scientists competing for what money there is.
That's made it tough for researchers like USC's Daryl Davies.
He's studying a drug that could help alcoholics kick their addiction. Testing it safely on humans will cost $1 million to $2 million over the next few years.
He's managed to get a few grants to cover a pilot study. For the rest, Davies is going to the public, hat in hand.
"I'm on the phones. I'm sending out e-mails," Davies said.
"I'm talking to friends all the time," he said. He tells them: "You know, can't you help a little more, another $50, another $25?"
Davies said he's raised several thousand dollars that way. He was never trained to fundraise, but it's quickly becoming part of the job for many scientists.
"And so we're learning," he said.
Jai Ranganathan, said the change is good because it encourages scientists to leave their labs and convince everyday citizens of the importance of their research. He is the co-founder of Sci Fund Challenge, a group that teaches scientists how to get the public interested in their work.
"It's a really big shift to say 'hey, wait a minute, we need to go out to the public,' " Ranganathan said.
He admitted not all important science is exciting stuff, like curing cancer or saving whales. But his group has proven that even less glamorous fields can raise plenty of cash. He said the key is scientists need to regularly talk, blog and post videos about why their work matters.
"And not to say we all have to be Don Drapers. We don't have to be black belts in marketing," he said. "But we all ought to have white belts in communication."
Crowd-sourcing funds raises some concerns for MIT science historian David Kaiser.
One benefit of the more traditional system of seeking money from the government is that the government has panels of experts who review proposals for potential problems, he said.
"Is the research ethical? Are their unforeseen or unappreciated risks that could come up?" Kaiser asks. These are the kinds of questions government review boards bring up.
He's worried researchers who get funds straight from the public won't get the benefit of this kind of oversight. But anything that helps fund important discoveries should be encouraged.
For USC scientist Daryl Davies finding new ways to get that funding is a constant concern.
He recently tried using Microryza, one of about half a dozen crowdfunding sites for the sciences. He asked for $20,000 for his research on alcoholism.
"I think it raised three of four hundred dollars," Davies said. "I'm learning by trial and error."
He plans to tweak his message and try again. After all, he figures there has to be a science to fundraising. And science is something Davies understands.