What do you want to be remembered for? 

It's a big-picture question, spurred by NASA's epic announcement that it has found evidence of liquid water flowing on Mars. 

You could argue the "remembered for" question is more spiritual than entrepreneurial--particularly if you believe in the separation of those spheres. But whenever I ask founders about entrepreneurs they admire, their answers return to company-builders whose vision is to change the world in a major, water-on-Mars-like way.

They name leaders like Elizabeth Holmes, Marc Lore, and Elon Musk. The reason? All three are making big bets on epic challenges. All three are playing the long game. They are tackling tasks that transcend the quick buck. Challenges so game-changing, so paradigmatic in scope, that some of them are more like societal initiatives than traditional businesses. 

If you haven't yet heard of Holmes, you soon will. She is the founder and CEO of Theranos, a Silicon Valley company with a $9-billion valuation. Theranos has developed an inexpensive, comprehensive blood test using a simple pinprick. At age 31, Holmes owns more than half of the company, making her America's youngest female self-made billionaire.  

All of which is great fodder for flashy headlines. But the reason founders admire Holmes is because she did it so slowly, for so long, without any fanfare. She founded Theranos in 2003, when she was 19. But her first 15 minutes of fame did not arrive until late 2013, when the company announced its partnership with Walgreens. Last year, her celebrity increased following profiles in Fortune, Forbes, and The New Yorker

In other words, she and her company were around for more than a decade before coming out of the woodwork. Go ahead and search for media mentions of Theranos prior to 2013. You'll find a few, but for the most part, Theranos was under the radar. (Though it behooves me to point out Inc. wrote about Holmes in 2006.)

That kind of walk-before-you-talk behavior is refreshing and respectable in today's hype-strewn entrepreneurial landscape. Most startups in 2015, especially those backed by loads of VC money, talk boldly before they've survived a year or turned a profit. By contrast, Theranos stayed quiet until its very visible partnership with Walgreens.

As for Lore, what's admirable is the scope of his ambition. In 2010, Amazon bought Quidsi, which Lore had co-founded, for $545 million. Now Lore is taking aim at Amazon with his new venture, Jet.com, which raised $220 million before its launch in July. It's a daunting challenge. And that is what inspires the admiration.

Regarding Musk, these things go without saying. His two startups, Tesla and SpaceX, are big bets with the potential to change our lives. They are epic, water-on-Mars-like propositions with long-term horizons. Which is fitting, considering how long it took for NASA's Mars Reconnaissance Orbiter (MRO) to be certain enough of water on Mars to make an announcement. 

Lujendra Ojha of the Georgia Institute of Technology, the lead author of the water-on-Mars report (which initially appeared in Nature Geoscience), first noticed images that might be water when he was an undergrad at the University of Arizona in 2010. And the MRO itself has been examining Mars since 2006. So, depending on how you slice it, the water-on-Mars announcement was five-to-nine years in the making. 

Talk about epic. Talk about admirable. Talk about playing the long game.

"It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet," Michael Meyer, lead scientist for NASA's Mars Exploration Program, noted in NASA's announcement. "It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future."

Which is why it's a mission that will always be admired--and remembered.