It began with a Tweet. On Wednesday, April 27, SpaceX posted two photos on Twitter, announcing plans to send a Red Dragon space capsule to Mars "as soon as 2018."

That, of course, got everyone wondering what the heck a "Red Dragon" was. And so, in due course, SpaceX CEO Elon Musk clarified that the capsule in question will be SpaceX's new Dragon 2 space capsule. This fact was then further clarified when SpaceX added that the Dragon 2 will be equipped with a "SuperDraco" propulsive landing system.

Questions, questions, so many questions

Of course, even then we had questions: Why is SpaceX going to Mars? What will it do when it gets there? And is SpaceX going alone, or is this some as-yet unannounced NASA mission it will be fulfilling (seeing as Neil deGrasse Tyson has assured us that SpaceX would have to be "delusional" to try to go to Mars without help from NASA)?

You've got questions. We've got answers

To try to clarify these nagging questions, I reached out to SpaceX earlier this week and got a bit more color on the company's upcoming mission to Mars. Basically, the story goes like this:

SpaceX is laser-focused on putting humans on Mars, and the sooner the better. In fact, Elon Musk himself has stated a 2025 deadline for his first manned mission to Mars, opining that "nine years" from now "seems like a long time." That said, there's a lot of prep work that must be done in the meantime.

To name just a few likely issues, the company will want to survey the terrain, and pick a landing site -- preferably one with access to resources useful for sustaining life, and producing rocket fuel. The company will also probably want to prepare the beachhead, so to speak, pre-landing such useful items as a prefab habitat, fuel, food, and water for astronauts to use upon arrival. All this will require a series of unmanned missions to Mars before the first manned mission can take place.

The first such unmanned mission will be in 2018, launching probably in April or May. It will begin with a launch of SpaceX's new Falcon Heavy lift vehicle -- due to make its maiden voyage in November of this year -- and end with a Dragon 2 landing vertically atop its own rocket exhaust on the Red Planet.

None of this, by the way, will be sponsored by NASA. As SpaceX advised, it will foot the bill for this 2018 Mars mission entirely on its own. More than that, the company will share any data generated by the mission with NASA -- free of charge.

How much will it cost?

Speaking of charges, as investors looking forward to the day when SpaceX ultimately IPOs, we're naturally interested in knowing how much SpaceX thinks a mission to Mars will cost. The company was entirely mum on that point. But here's what we know.

On the high end, NASA spent $2.5 billion to send the Curiosity Rover to Mars in 2011. That's about $2.65 billion in today's dollars. The cheaper Phoenix Mars Mission put a lander on Mars for just $386 million in 2008 ($427 million today). Both those missions used extremely high-cost launch vehicles from Boeing (NYSE:BA) and Lockheed Martin's (NYSE:LMT) United Launch Alliance, however, to get them to their destination -- Lockheed Martin's Atlas V in the case of Curiosity, and Boeing's Delta II in the case of Phoenix.

India's recent Mangalyaan orbiter, on the other hand, went to Mars for a grand total of just $74 million (including $25 million for the orbiter). According to new reports, the launcher on that mission, a domestic Polar Satellite Launch Vehicle, cost only $15 million -- roughly an order of magnitude cheaper than anything Boeing or Lockheed have to offer.

That's a price tag I suspect even SpaceX would be hard pressed to match. According to its published prices, the cost of launching a Falcon Heavy into Earth orbit will average $90 million. Add the cost of extra fuel to escape Earth orbit and reach Mars, add a bit more cost for equipment aboard the Dragon lander -- we're still probably only talking a total mission cost in the low $100 million range.

That's a bill Elon Musk should be able to foot easily.

What it means for investors

Unless and until SpaceX goes public, most of the above probably seems academic. We can't invest in SpaceX today; perhaps we never will. Be that as it may, one thing is clear: Mankind is going to Mars, and sooner than you think. That this will open up the possibilities of new investments -- literally out-of-this-world investments -- seems almost certain.

Hold on to your hats, folks. The world is changing as we watch.