by Manfred “Dutch” von Ehrenfried

An early design for a crewed nuclear-powered Mars mission

Credit: NASA

There are many types of early human Mars mission profiles but which will be used won’t be determined for many years. There are various reasons why; it is not because we don’t know how to get there, are unprepared for the risks, or don’t know how to build the vehicles. So what’s stopping us from planning the mission, building the hardware, and departing for the Red Planet? We have discussed sending people to Mars for at least 70 years, since Wernher von Braun first released his seminal book The Mars Project in 1953.

No matter the mission type, it will take a continued effort by many nations over a period of time that transcends most political administrations to reach Mars, so the need for assured continued funding and resources is profound and the costs will be enormous. While a few nations could fund a modest mission—such as a crewed Mars flyby—it may take a global commitment involving many nations for a crewed mission to the Martian surface. NASA is currently funding the International Space Station, the Artemis Program, and robotic missions to Mars and elsewhere—and they do so with a budget approximately one-tenth of that during the Space Race. How many initiatives can they undertake at one time? And if such a sortie is first attempted by a private entity such as SpaceX—as Elon Musk plans—can this possibly be done without a substantial government infusion?

HOW TO FLY TO MARS

There are seven types of human missions to Mars.

A Free Return Flyby is arguably the cheapest, quickest, and safest way to send humans to Mars. In this scenario, the spacecraft would simply fly past the planet, not orbiting or landing. There is a lot of science that can be learned along the way, as well as while in the neighborhood of Mars. In addition to the basic human mission, satellites with a propulsive capability can be launched when near the planet and left in orbit.

These can be instrumented to achieve specific science goals in addition to serving as navigation and communication aids for subsequent missions and could be targeted to Mars’ twin moons. A cluster of small satellites might also be deorbited for different science objectives.

While there are several ways to perform a Mars flyby, the option requiring the lowest delta-v, or velocity change, is to launch into a heliocentric orbit that intersects the planet on either the outbound or inbound leg. As a result, there are two opportunities, seven months apart, during each two-year Earth-Mars synodic period (the time required for Mars to return to the same position relative to the sun as seen by an observer on Earth). Such missions would spend between one and two days within Mars’ sphere of influence. In one case, the closest approach to Mars is on the order of 6,214 miles (10,000 kilometers) and occurs near the dawn-dusk terminator. In another case the closest approach is 311 miles (500 km).