On-orbit rendezvous is expensive and dangerous.

Final Artemis Project crew arrives at the orbiting assembly fixture. Artwork by Vik Olliver

This technical objection focuses on the Artemis Project Reference Mission. Our mission plan calls for assembling the spacecraft in low Earth orbit, using two or more launches to get all the parts of the moonship into space.

The concern comes from a perceived risk in bringing the spacecraft together in orbit. The Apollo spacecraft were all launched on a single Saturn V booster, which might lead someone to believe that this is the only way to do it.

However, we're not at all worried about this flight technique. On-orbit rendezvous was a big worry for NASA, when the agency first got its commission to land a man on the moon. At that time, nobody knew if it was even impossible; but in the years to come NASA would perform the rendezvous maneuver again and again.

On-orbit rendezvous has a long and proven history; NASA and the Russian Space Agency have honed the techniques and all the supporting data (such as models of Earth's gravitational field) to near perfection.

Gemini proved it

NASA has been conducting spacecraft rendezvous in Earth orbit since they developed the techniques as part of the Gemini program in the 1960's.

Apollo did it

The Apollo spacecraft were launched on one huge Saturn V rocket, but they still had two docking maneuvers and one full rendezvous -- in lunar orbit -- on every landing mission. Once the Apollo spacecraft were on their way to the moon, the Command Module separated from the booster and turned around to rendezvous and dock with the Lunar Module. Then, after their explorations on the lunar surface were complete, the Apollo astronauts flew the Lunar Module Ascent Stage back to lunar orbit, where they made their rendezvous with the orbiting command module.

Apollo spacecraft also performed on-orbit rendezvous, in Earth orbit, for each of the three Skylab manned missions, and for the Apollo-Soyuz Test Project.

Shuttle does it

NASA has performed so many on-orbit rendezvous maneuvers with the Space Shuttle that we've lost count of them all:

• Every time the Space Shuttle has deployed a subsatellite and recovered the satellite.
• Each servicing mission to the Hubble Space Telescope.
• Recovery of the Palapa and Westar communication satellites.
• Each mission to the Russian Mir space station.
• The dramatic rescue of Intelsat, where NASA had 3 astronauts go outside the spacecraft on the same EVA sortie, required multiple rendezvous maneuvers.
• The Japanese launched a satellite from Japan, which the Shuttle picked up and returned to Earth.

Russians keep on doing it

Throughout the long history of Russian space stations, from the seven Salyut stations to the Mir, the Soviet Union and then the Russian Space Agency made repeated on-orbit rendezvous maneuvers. Each crew rotation with Soyuz spacecraft required a rendezvous with a space station. They even perfected the technique of automated, unmanned rendezvous for their resupply missions and the flights that added additional laboratories to the Mir.

On-orbit rendezvous saves us money

We plan to build our spacecraft in pieces and launch each piece separately. Our crews will assemble the parts in Earth orbit before they head out for the moon. This adds quite a burden of cost to the program, to integrate all those individual pieces and plan all those flights. However, it also saves the Artemis Project a lot of money.

The initial cost saving comes from not having to develop a huge booster to put all the spacecraft on orbit in one launch. It costs a lot more to develop a reliable launcher than an orbital spacecraft. Launchers have to deal with Earth's deep gravity well. They have to work in varying condidtions of winds and weather. They have to be designed with extensive analysis of range safety -- where the booster stages fall back to Earth and where things go if there's a mission abort. And during the initial ascent to orbit, things happen fast; there's not much time to recover from a glitch, so everything has to be tested, analyzed, and test again until it's as nearly perfect as human ingenuity can make it.

In the long run, the modular design of our spacecraft saves the program money because the sundry components can be used in future spacecraft without the need for a lot of redesign. The propulsion module for the Lunar Transfer Vehicle can be adapted to future moonships. So can its forward and aft service modules, as well as its pressurized command module. The berthing systems can be perfected and adapted to new missions as they come along.

Solar power arrays, external antennas, and EVA support equipment can also be used as off-the-shelf designs once the initial development is done. And instead of developing each flight to the moon as a unique design project, we can learn from each mission to tune the parts for future missions.

Rendezvous experience prepares us for the future

Finally, we need to develop experience with on-orbit rendezvous to prepare for the future of the lunar community. Moon-bound commercial spacecraft will make rendezvous with fuel depots and eventually with orbiting hotels. Lunar industries involved in servicing and salvaging satellites will need to make rendezvous with their customers' hardware. Returning spacecraft will need to brake into Earth orbit to make rendezvous with orbiting space stations and hotels. Nearly everything the lunar community does in space will require rendezvous.

The time may come when spacecraft bound for Mars and other planets launch from the moon on electric mass drivers. We can image a series of spacecraft modules, all interconnected, speeding along acceleration rails like an interplanetary freight train before they make it to orbit and form up into their cruise configuration.

It's just as likely, though, that these spacecraft will be launched in pieces and make their rendezvous on the way to Mars. Then, once they arrive in Mars orbit, they will again need to perform a rendezvous maneuver with a space station there.

So, we will continue to include on-orbit rendezvous in our mission plans, and we will perfect these techniques in each environment -- Earth orbit, lunar orbit, and even in interplanetary space -- as we begin our journey into the Cosmos.

Artemis Project Reference Mission spacecraft images in this document are provided courtesy of The Lunar Resources Company. They can be ordered on line from Lunar Traders: Post cards, posters, and other prints of these spacecraft images are available from the Lunar Traders Catalog. Spacecraft designs are copyright and trademarks of The Lunar Resources Company; all rights reserved.