The Space Review

 
Soyuz flying around the Moon
A Soyuz, with a logistics module attached, rounds the Moon on a circumlunar mission proposed last month by CSI. (credit: CSI)

Soyuz to the Moon?

Conventional wisdom over the last several months has been that any human return to the Moon will not—barring an unlikely crash Chinese program—take place for a decade or more. The shuttle, obviously, is not capable of such a mission, and its successor, the Crew Exploration Vehicle (CEV), is not planned to enter service before about 2014, assuming all goes as planned. That would indicate that it will be at least that long, and perhaps longer, before humans again venture beyond low Earth orbit.

The shuttle, however, is not the only means of carrying people into orbit; the Soyuz spacecraft has performed that duty for over three decades. The Soyuz today is seen exclusively as a taxi and lifeboat for crews on the International Space Station, but a few see an expanded role for the venerable spacecraft. At a presentation during the Return to the Moon conference in Las Vegas July 17, David Anderman, chief operating officer of Constellation Services International (CSI), offered an innovative approach that could turn the Soyuz from an ISS ferry to a circumlunar spacecraft with potential commercial applications.

A Soyuz lunar architecture

At first glance it seems unlikely, even preposterous, that a Soyuz spacecraft could be sent to the Moon and back. However, with the right approach, and the right additional hardware, Anderman believes that “every Soyuz launched to the ISS is a potential lunar spacecraft.”

With the right approach, and the right additional hardware, Anderman believes that “every Soyuz launched to the ISS is a potential lunar spacecraft.”

The key to this “Lunar Express” approach is addition of a new component, a logistics module, to the Soyuz. In the strawman mission architecture Anderman outlined in his conference presentation, the logistics module and an upper stage are launched into an ISS orbit by a generic launch vehicle. Anderman stressed that the logistics module was not tied to a specific launch vehicle to aid in the flexibility of the mission design; in an animation he showed at the conference the module was launched by a rocket bearing a NASA logo but resembling neither an Atlas nor a Delta.

Once the module and upper stage were in orbit, a Soyuz spacecraft that had completed its half-year stay at the ISS would undock from the station and dock with the logistics module. The upper stage attached to the other end of the logistics module then fires, sending the complete spacecraft on a free-return circumlunar trajectory. The upper stage is jettisoned after the translunar injection burn, leaving the Soyuz and logistics module to complete the six-day round-trip mission. Back at Earth, the Soyuz return module separates from the rest of the spacecraft, as normal, and performs a double-dip reentry to handle the higher velocity of returning from the Moon.

A similar approach could be used to recycle Progress cargo spacecraft at the end of their ISS missions. Instead of allowing the spacecraft to burn up in the Earth’s atmosphere, they could be docked with a logistics module and upper stage. In this case, instead of sending the spacecraft around the Moon, the Progress spacecraft would be sent to the Earth-Moon L1 point. Several such spacecraft could be docked together there, Anderman suggested, creating a supply depot and perhaps the core of an eventual human base that would be used a staging point for missions to the lunar surface or beyond.

While sending a Soyuz to the Moon might seem novel, Anderman noted that it had already been done, in a sense: In the late 1960s the Soviet Union sent several stripped-down unmanned Soyuz spacecraft, called Zond, to the Moon in a bid to beat the Americans.

The linchpin to both architectures is the logistics module, a spacecraft that doesn’t yet exist. As envisioned by Anderman, the logistics module would be a simple cylindrical module with docking interfaces at either end, one for the Soyuz or Progress and the other for the upper stage. The module would be equipped with a docking radar and communications system designed to work at lunar distances. The module would also carry the food, water, and other supplies needed for a manned circumlunar mission, and provide additional habitation volume. Perhaps most importantly, though, Anderman said, is that the module would carry a new toilet: the toilet currently used on Soyuz missions, located in the orbital module, is designed to support three people for only two to four days. Anderman gave no estimates about how long it would take to develop this module, or at what cost. Given that CSI’s focus to date has been on commercial resupply missions to the ISS, the implication was that the logistics module might be derived from vehicles the company would develop to carry supplies to the station.

While sending a Soyuz to the Moon might seem novel, Anderman noted that it had already been done, in a sense. In the late 1960s the Soviet Union sent several stripped-down unmanned Soyuz spacecraft, called Zond, to the Moon in a bid to develop a manned lunar vehicle that could beat the Americans to the Moon. The Zonds, superficially similar to today’s Soyuz but lacking an orbital module, suffered some problems during their flights, including guidance problems, and the program was canceled before any manned missions could fly once the US beat the USSR to the Moon. The Soyuz spacecraft used for Lunar Express missions would have to carry the heavier heat shields developed for the Zond program, incurring a 300-kilogram mass penalty. However, Anderman suggested that this mass could be recouped as more powerful variants of the Soyuz booster enter service in the years to come.

Commercial potential

It’s one thing to say that it’s possible, at least in theory, to convert a Soyuz spacecraft into a manned lunar spacecraft. A bigger question is why anyone would want to do it. In his presentation Anderman offered several reasons why the Lunar Express plan could prove worthwhile. The missions would, first and foremost, allow humans to return to the vicinity of the Moon far sooner than currently envisioned by the Vision for Space Exploration. These missions could also serve as a pathfinder for the development of the CEV, providing guidance for designing new vehicles that would fly in cislunar space. The missions could also serve as a platform for new experiments, such as lunar polar flyby missions as well as the use of tethers (between the spacecraft and the upper stage) to test partial-gravity environments.

“Would someone be willing to pay for a premier space adventure—first an initial week-long stay at ISS, and then a week-long trip around the Moon like Apollo 8 or 10?” Miller asked.

With the US committed, though, to developing a CEV, how could a Lunar Express mission be developed? Anderman suggested that it might be possible for a commercial company—presumably CSI—to put together such a mission with international partners. He outlines one hypothetical mission involving Russia, ESA, and a commercial customer. Russia would provide a Proton launch of the logistics module, as well as use of the Soyuz spacecraft after its mission to the ISS is completed. ESA and the commercial customer would then each pay an unspecified fee for a seat on the lunar portion of the mission. Alternatively, he said, ESA could launch the logistics module on an Ariane 5; that booster is powerful enough, he noted, that it might permit a lunar orbit mission, rather than a free-return flyby.

Charles Miller, chief executive officer of CSI, said in an interview after the conference that the company was looking at the commercial potential of such a mission. “Would someone be willing to pay for a premier space adventure—first an initial week-long stay at ISS, and then a week-long trip around the Moon like Apollo 8 or 10?” he asked. “Would another nation be willing to pay for the second seat, and send their first citizen ever around the Moon? What are the advertising possibilities? These are very interesting questions. We might be able to do this without a dime of NASA money.”

While Anderman’s presentation about Lunar Express at the conference seemed more in the mode of a thought experiment—what could be done to convert a Soyuz into a lunar spacecraft—Miller said that his company was actively pursuing partners to help develop such a mission. “CSI is primarily focused on commercial ISS resupply,” he said. “Therefore, CSI has decided to look for partners, and is in early discussions with potential partners, to find out if there is interest in a commercial lunar flight in the 2008 time frame.”


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