Once upon a time, the space race was all about the US and Russia. Now it's about private companies competing for innovations and bragging rights. No accomplishment would be bigger than landing a human on Mars. 

Boeing says it will get to the Red Planet before SpaceX does. SpaceX founder Elon Musk had a short response to that idea: "Do it."

This mild war of words started when the TheStreet interviewed Boeing CEO Dennis Muilenburg, who told the publication, "I firmly believe that the first person to step foot on Mars will get there on a Boeing rocket."

TheStreet founder Jim Cramer shared this sentiment on Twitter and Musk responded with his two-word statement: "Do it."

SpaceX says it wants to send a cargo mission to Mars in 2022 while targeting 2024 for a crewed mission using an advanced rocket system called the BFR. Musk sees this as the first step to creating a self-sustaining human civilization on Mars.

If would be interesting if the SpaceX BFR arrived at Mars and found a Boeing rocket already there. Boeing is currently working with NASA on a Space Launch System meant to propel people and cargo "beyond our moon and into deep space."

Musk's short comment in response to the Boeing story may not be as chippy as it sounds at first. It's not a snipe. It's a challenge. There's a healthy spirit of competition in the commercial space race, which also involves Amazon founder Jeff Bezos' Blue Origin venture. 

A human-crewed spaceship will eventually launch to Mars. Only time will tell if it's powered by Boeing, SpaceX or someone else entirely.