The asteroid Ryugu comes relatively close to Earth twenty seven times before the end of the century. It also comes close to the orbit of Mars on its journey around the Sun. Some of those orbits will include both a close encounter with Earth and with Mars. According to the web site Asterank, on December 29, 2020, Ryugu comes very close to Earth, relatively speaking. It will be 0.061 AU, about 5.7 million miles, away. It will be even closer on December 21, 2033; a scant 4.4 million miles. These distances are 6 to 8 times closer than 36 million miles, which is the closest Mars gets to Earth, and a hundred times closer than 400 million miles, the farthest point.

Orbits Ryugu, Mercury, Venus, Earth, Mars

What if we intercept Ryugu with autonomous drones towing the equipment necessary to mine Ryugu for some of the $83 billion dollars worth of nickel, iron, cobalt, water, and frozen gasses that it contains? This equipment is set up, solar panel arrays are unfolded and activated, and the asteroid swarms with prospector drones cataloging material and locations. All this takes place as the asteroid proceeds in its orbit about the Sun. It will be quite busy until a suitable load of material is collected and secured for a trip back when the asteroid comes close to Earth again.

What if the holes and tunnels the mining drones excavate for ore are repurposed as living quarters for astronauts to hitch a ride to Mars, do a year or three of studies, and then hitch a ride back? That presupposes a workable spacecraft that can land on Mars and take off again after sitting months, possibly years, on the surface of Mars and be attached or otherwise stowed on our shuttle asteroid. Does this idea sound any more incredible than a ship that will do that plus make the journey from Earth to Mars while keeping passengers safe from radiation, bone loss, and well fed? Besides that, it would be there for future missions for hundreds of years into the future; a permanent, luxury shuttle to Mars and back.

Ryugu; an asteroid about a kilometer in diameter.

A hollowed out asteroid could haul power, water mining, food growing, and shelter building equipment packaged in appropriate landers to Mars orbit. The asteroid shuttle could even be spun up to provide artificial gravity to minimize bone loss over the course of the journey. A deep space tug stowed on the asteroid would drag this equipment from the asteroid to an orbit around Mars for insertion and landing. Autonomous robots could begin setting up camp, so to speak, getting ready for the human occupation.

On the next trip, the asteroid shuttle will carry a vehicle with the ability to orbit Mars, land, and take off. Along with that vehicle will be the first people, a cherry-picked group of scientist explorers. With so much of their survival equipment already in place, the first humans on Mars will have much more time to devote to science rather than just staying alive. The asteroid itself would lend itself to a great lab for deep space, vacuum, and microgravity experiments. A good telescope would be included for closer looks at denizens of the asteroid belt.

This is similar to the scheme Elon Musk proposes, a two-part trip using the Big Falcon Rocket. Two BFRs locate water and deliver equipment in 2022. A second pair of crewed BFRs plus two drone cargo BFRs, in 2024, deliver more equipment and the astronauts.

NASA’s version of the Mars mission depends on the development of a Deep Space Gateway, DSG, sort of a mini-ISS orbiting the Moon. A Deep Space Transport, DST, would be NASA’s answer to SpaceX’s BFR.

Deep Space Gateway and Deep Space Transport — courtesy NASA

Even if it were decided to use an asteroid as a shuttle to Mars, the BFR or the launch system for the DST would still have to be developed and used to get the bigger pieces of equipment into orbit for the mission. From there the BFR, DST, or a space tug would ferry the equipment to the asteroid at its closest approach to Earth. If the space tug is used, it would free up the BFRs to be loaded with some of the more expensive metals mined from the asteroid and haul that back to the Earth’s surface. Everybody wins! The Mars explorers would get there more safely and in much more comfortable quarters. Elon Musk makes money hauling exploration equipment into space and asteroid material down to Earth. The only musical chairs loser might be the DST, which is basically a deep space ferry similar to the space tug. But there definitely is still a need for this type of vehicle, and it may very well be used in conjunction with the BFR for the role of role of deep space tug. It may be better suited for that purpose than the BFR because a large portion of its capacity is not given over to reentry shields and landing engines as in the BFR.

There are many asteroids out there that swing by Earth before heading back into space. They will do this for centuries. We should take advantage of these durable, long-lasting, natural shuttles to other parts of our Solar System.

The exploration of space is a juggle of restraints put in place by the physical laws of our universe. In the end we must make a decision on how it will be done. Hopefully, that decision will be made with the safety of the crew uppermost in mind. Using an asteroid to make the journey to Mars and back sounds, on paper at least, like a safe, comfortable, less expensive route to take. It very much depends on how quickly and intelligently the asteroid mining industry advances over the next few years.