MARCUS LINDROOS (firstname.lastname@example.org)
(This article was written in December 1994-March 1995 on an HP95LX palmtop computer. Illustrations were done with Arts & Letters. Special thanks to Nadia Soderman for proof-reading the finished text)
Luna 2001 is a basic, low cost manned lunar program based on an earlier Soviet proposal ("LK-700") from the 1960s. Key elements include Russia's 2-man Merkur capsule from the LK-700, Zvezda programs and a new service/propulsion module or Orbital Transfer Vehicle. The latter will be based on American technology. No heavy lift launch vehicle is required, only medium capability launchers such as Russia's Proton rocket. The number of launches per mission is two, decreasing to one once an unmanned LOX fuel mining/cryo storage facility has been set up on the lunar surface.
This paper also (briefly-) deals with other aspects of incremental lunar programs (geopolitical & economic considerations) such as ESA's Moon program and Krafft Ehricke's Extraterrestial Imperative.
-Cost effective, Apollo level pathfinder missions using existing systems mostly developed for other, commercial purposes.
-Creating a number of useful "building blocks" (lunar LOX mining, Orbital Transfer Vehicle upper stage) that will be required by future lunar colonies once the reusable "SSTO era" of space exploitation has begun.
-Initially, the Luna-2001 vehicle will serve as the lunar equivalent of the Russian Soyuz/Progress spacecraft - i.e. a small, expendable system capable of delivering 2-3t payloads to a small Moonbase. Eventually the reentry capsule may be dropped and replaced by an Apollo Lunar Module type crew cabin (Phase 3). The vehicle would then be permanently based in lunar orbit and on the Moon, and be fully reusable.
2.PREFACE - CHELOMEI'S LK-700 PROGRAM
On November 16, 1966 the Chelomei design bureau proposed a direct manned flight to the Moon and back - the more complicated lunar orbit rendezvous option used by Apollo and the failed Soviet L-3 project would not be required. Chelomei's program was called LK-700 and would have used a heavy lift derivative of the Proton rocket, the UR-700. No authoritative drawings or descriptions of the vehicle are available, but we know the UR-700 would have used a new giant, modular first stage while slightly modified Proton hardware was to serve as its upper stages. The first stage would have used eight or nine RD-270 engines, producing a launch thrust of up to 56,500kN (vs. 34,000kN for the Saturn V). The RD-270 was developed by Valentin Glushko, the chief designer of Soviet rocket engines who boycotted the N-1/L-3 project because of a personal feud with program leader Sergei Korolev. Consequently the N-1 designers had to make do with comparatively inefficient engines, a major reason for the program's eventual failure. UR-700 was cancelled in 1970. Hindsight suggests a compromise between the Korolev (main designer of all Soviet spacecraft at the time) and Chelomei/Glushko (engines, large carrier rockets) design bureaus could have saved the Soviet manned lunar program.
The LK-700 craft is shown in Figure 1(source:Ralph Gibbons/QUEST magazine (4/92)). On top is the small 2-man descent capsule, described as "similar to the American Gemini," which would turn up again in the 1980s as part of the Zvezda modular spacecraft. This capsule, also known as Merkur, would have a mass of only two metric tons (compared with 3t for Soyuz or 5.5-6t for Apollo). The cylindrical section attached to it contains the fuel for the return trip, while the central bulbous rocket unit below the spacecraft is used for the major part of the descent to the lunar surface. It would have been jettisoned a few km above the surface. Finally, there is a large translunar injection stage. This has four engines and is apparently a modified Proton second stage. All LK-700 propulsion units would use a dense, storable hypergolic propellant. The total mass of the LK-700 craft might be about 40-41t, including a braking motor of approx. 28-29t. The whole assembly (including the translunar injection stage) probably weighted about 130t in low Earth orbit.
3.LUNA-2001:A MODERN VERSION OF CHELOMEI'S PROGRAM
Computer, material and propulsion advances since the late 1960s make it possible to build a far more efficient version of the LK-700 craft. In fact, if America's highly reliable RL-10 engine were used on the lander and descent stage, the mass in low Earth orbit would decrease by 50%. The Phase 1 configuration of Luna-2001 is small enough to be launched on two Proton rockets rather than a heavy lift vehicle. Lunar oxygen mining (where moonsoil is heated to produce oxygen fuel for the return trip - the hydrogen is brought from Earth) would reduce the mass by another 50% - to just nine metric tons from the original total of 41t using inefficient hypergolic fuel! The Phase 2 configuration is compact enough to fit on a single, slightly upgraded Proton launcher. Table 1 lists the projected mass ratios of LK-700 and Luna-2001 Phase 1, 2.
Table 1 - summary of Luna-2001
dry wt.: 2.2t?
wet wt. 9.0t?
dry wt.: 5.0t?
wet wt.: 30t?
dry wt.: 2.1t
wet wt. 7.0t
dry wt.: 1.8t
wet wt.: 9.0t
TOTAL: 2 x 9t
TLI stage:2 x 13t
= 2 x 22t
Launcher: 2 x Proton
Same Isp,mass as L-2001 Phase One descent stage
3.1 Luna-2001 Phase 1 configuration
While fuel production facilities on the lunar surface are inevitable in the long run, a "quick" mission to the Moon would not require this capability if two medium capability launchers and OTVs are used. Figure 2 shows a summary of the Phase 1 mission profile. The carrier rockets depicted are Russia's Proton with an American Centaur G' 4th stage, and ESA's Ariane-5 with an H10 upper stage from the Ariane-4 program. Notably, both rockets currently lack a powerful enough upper stage. The US Air Force's Titan IV - Centaur G' could, on the other hand, be used almost off-the-shelf but is probably too expensive at almost $300 million per launch.
The Luna-2001 Merkur/OTV spacecraft with two cosmonauts is launched on a translunar trajectory by one of the rockets mentioned earlier on. The other lifts a descent/braking stage based on the OTV propulsion module but without any long duration cooling, power, RCS systems etc.. It would carry 2t of additional fuel for lunar orbit insertion and landing. Both units dock shortly after the translunar injection burn out of low Earth orbit (rendezvous in Earth or lunar orbit would be too costly in terms of fuel). The descent stage provides the lunar orbit insertion burn, and powers the craft during the lunar descent phase as well. At an altitude of a few dozen km, the stage would become empty and be jettisoned as the Merkur/OTV craft fires its own engine to land.
Phase 1 recurring costs would obviously be higher since two rocket launches are required. On the plus side, Phase 1 would be a "stand alone" program since no expensive moonbase hardware (LOX propellant factory etc.) would have to be landed in advance. Consequently any area could be visited, not just sites located near the propellant factory. Phase 1 would also be safer, the crew could return from the Moon without first having to refuel the craft with lunar oxygen.
3.2 Luna-2001 Phase 2 configuration
The next phase, a single-stage, single-launch manned lunar mission, will require that a significant infrastructure be set up on the Moon. The following equipment will be essential:
-Robotic soil excavator/hauler
-Lunar liquid oxygen plant
-Mobile laboratory rover (MOLAB)
-Mobile LOX storage facility & habitat module (MOLAB trailer)
This may seem like a lot of equipment, but keep in mind that countless unmanned telerobotic landers and rovers will probably have been sent to the Moon before that, performing a systematic exploration of the Moon's resources. Until these robotic "pathfinders" have done their task, there is no compelling reason to send humans to the Moon. Luna-2001 is the beginning of the final phase, or the initial development of a manned lunar outpost. Before that, unmanned robots will have demonstrated the feasibility of _in situ_ fuel production and construction techniques using lunar materials. The "building blocks" listed above would each have a maximum mass of about 2-2.5t. They would be brought to the moonbase site by conventional unmanned landers such as International Space Enterprise's ISELA-1600, or an unmanned version of the Luna-2001 craft. As before, existing ELVs such as Proton or Ariane would be used rather than heavy-lift boosters.
Luna-2001 makes as much use of lunar resources as possible to keep down launch costs. The spacecraft is very cramped and contains living space for a crew of two, plus some room for their spacesuits and other equipment. The journey will take three days and the crew will transfer to the Mobile Laboratory (MOLAB) immediately after landing on the Moon. MOLAB will be their home on the lunar surface. Using this, the crew could travel to interesting sites several hundred kilometers away or visit unmanned outposts containing scientific equipment (telescopes etc.) in need of repair. When it is time to bid adieu to the Moon, the crew transfers some 3t of lunar LOX from the cryo storage facility to the lander, then blast off from the lunar surface. The LH2 would be brought from Earth.
One drawback is that the Luna-2001 lander only can reach sites where the LOX cryo storage facility is. This restricts all missions to where the moonbase (=LOX plant) is located, probably the south polar regions. But the MOLAB could carry liquid oxygen for the return trip to a site chosen in advance. Since the Luna-2001 craft would have to make a rather risky direct landing in order to save fuel, it is very important that the MOLAB acts as a landing beacon, guiding the lander to a safe site. Unfortunately, Luna-2001 will have very limited maneuverability so a detailed map of the lunar terrain will be required to ensure a safe landing.
Since the Luna-2001 craft only can carry limited supplies of food and water ( < ~100kg ), initial missions would be limited to about two weeks. A lunar outpost might recycle all water and waste products, growing most of the food inside a closed loop life support system. This would drastically reduce the amount of supplies that would have to be brought from Earth.
3.3 Luna-2001 & Rendezvous in Lunar Orbit
After Phase 2, the logical next step is rendezvous in lunar orbit between two craft - an expendable Orbiter launched on a Proton or Ariane-5, and a reusable Lander permanently based on the Moon. Figure 3 shows the flight plan. The Orbiter (which could be based on the Luna-2001 craft, perhaps carrying a larger Apollo type 3-man crew capsule but no landing equipment) would transfer two Moonbase-bound astronauts and hydrogen fuel to the Lander, after the spaceships have docked in lunar orbit. The Orbiter then returns to Earth with two astronauts from the Moonbase. As before, the Lander's LOX would be extracted from moonsoil.
The advantage with this method is that the payload brought from LEO to the lunar surface increases by up to one metric ton per launch (plus ~0.9t of LH2 for the Lander). This is because the Lander can be made lighter since there is no need to land the reentry capsule (heatshield,parachutes etc.) on the Moon. Another advantage is that the Lander can now be used many times, while using an intermediate lunar orbit is safer than Phase 2's direct descent to the surface. The main disadvantage is that if the fuel transfer in lunar orbit does not come off, the Lander crew will be stranded in orbit. A small orbiting space station / "fuel depot" would solve this problem.
3.4 Luna-2001, space stations & reusable launch vehicles
When reusable single-stage-to-orbit vehicles such as the Delta Clipper or Europe's SKYLON replace expendable rockets in the early 21st century, the Phase 3 Orbiter can be retired from service. Instead, a fully reusable aeroshell equipped OTV would ferry satellites and other payloads from LEO to GSO and lunar orbit.
Small space stations in Earth and lunar orbit could serve as extremely useful "space docks" and repair/refuelling nodes. Russia's Mir, ESA's Columbus module and Space Industries' Industrial Space Facility (ISF) could be adapted into habitats for such bases. In-orbit repair of equipment and reusable upper stages (both were briefly part of NASA's Shuttle Transportation System and Space Station in the early 1970s and 1980s) would finally make economic sense.
A circumlunar space station would be much more accessible than a base on the lunar surface, especially if small expendable launchers have to be used. In my opinion, the development and launch of the lunar space station (plus a Phase 3 Orbiter) should precede manned missions to the lunar surface. It could act as a control center for telerobotic ground systems launched from Earth directly to the lunar surface. This station could also function as an industrial research laboratory, experimenting with lunar samples brought to it by unmanned landers. Tasks include research and manufacturing of materials from lunar resources in a microgravity environment, and life sciences (the lunar space station would require the same capabilities [radiation shielding etc.] as a manned spacecraft to Mars or near-Earth asteroids).
A major problem with the circumlunar space station is how to launch it from LEO to an orbit around the Moon. If Proton or Ariane rockets are used, even a small 15-20t station would require three launches per mission plus in-orbit assembly in LEO. Alternatively, a heavy-lift rocket such as the Energia could be used. There is a better method, however. Both the station and unmanned cargo craft could be put into translunar trajectory using ion thrusters. An electrically propelled "tug" powered by solar energy could slowly spiral out from LEO with the payload (Mir, Columbus, ISF modules, or ESA's ATV cargo craft). The solar-powered ion rocket could also transport satellites to higher orbits, so the technology will clearly be important in the long run.
4.LUNA-2001 SPACECRAFT COMPONENTS
See Figure 4 for an illustration of the basic Luna-2001 craft (Phase 1,2). The vehicle is about the size of an Apollo CSM and consists of the following elements:
-"Merkur" space capsule (Russian,developed)
-Service Module (Russian, loosely based on LK-700)
-OTV Propulsion Module (USA, new)
-Proton/Ariane/Titan ELV (slightly upgraded, new upper stage)
-MOLAB rover (USA?, new)
4.1 "Merkur" space capsule
As noted earlier, the Merkur capsule was briefly revived in the late 1970s and early 1980s with the TKS/Zvezda program. The Mir modules and International Space Station Alpha's FGB propulsion module are based on the Zvezda craft. Although Merkur was not retained, restarting production of this relatively small and simple capsule should not prove too difficult.
4.2 "Merkur" Service Module
The OTV/Merkur adapter (which tapers from about 4m to 3m at the base of the Merkur heatshield) contains water tanks, batteries, and a small cargo bay. It would have to be developed from scratch.
4.3 Orbital Transfer Vehicle
The OTV is the pivotal technology. It uses advanced electronics, lightweight materials and powerful rocket engines the Soviets did not have in the late 1960s. The OTV is loosely based on a study by the European Launcher Development Organization (ELDO) from the early 1970s, briefly proposed for NASA's Space Shuttle program.
The Orbital Transfer Vehicle will feature a single Pratt & Whitney RL-10 engine, already used on the Centaur upper stage. The RL-10 has been in production since the early 1960s and is considered very reliable. The lunar version would have a thrust of 65,000N and require a 30-100% variable throttling capability. P&W has already developed such an engine, the RL-10A-5, for the DC-X vertical takeoff & landing SSTO testbed vehicle.
Since the Proton and Ariane-5 boosters only can launch approx. 9 metric tons on a translunar trajectory, the OTV will have to be of lightweight construction. Its dry mass is specified as 2.1t, including the Service Module. The fuel tanks of the Phase 2 OTV would have an internal volume of 19 cubic meters. In comparison, ESA's H10 upper stage (31 cubic meters fuel volume) has a dry mass of 1.3t while the original Centaur (40m3) weights 1.7t. The ELDO OTV study assumed a dry mass of 1.8t (31m3 fuel), so the total mass of the Luna-2001 OTV version should be well within the state of the arts.
4.4 MObile LABoratory (MOLAB)
The MOLAB will have a range of a few hundred kilometers and a life support system capable of supporting a crew of two. The rover can be controlled from Earth using telepresence (in unmanned mode) or by the cosmonauts (in manned mode).
A problem is the limited capability of the Proton/ISELA robotic vehicle used for cargo missions - 2000kg per launch. To keep down the weight, the MOLAB consists of two parts: a small pressurized rover and a "wagon" containing a small habitat module plus fuel tanks/LOX transfer equipment. The total dry mass would be 4000kg.
5 POLICY SUMMARY - WHY RETURN TO THE MOON?
Figure 5 shows the main stages of the European Space Agency's Moon program, as well as Krafft Ehricke's lunar development proposal. LUNA-2001 favors the same approach.
The future of space activities is going to depend heavily on the ability of the various space agencies to learn to live within level funding at best, and to carry out "practical" programs which help to deal with real problems such as pollution etc. (i.e. Earth observation). The Cold War and limitless funding for "propaganda missions" such as Apollo is over. Future Man-in-Space activities will require both less costly launchers and international cooperation. The former problem is only now being addressed in the US, Europe and Japan as new reusable spaceplanes have been proposed. Permanent outposts on the Moon or Mars will not be possible until "the next generation" of economical launchers enter service.
Unmanned lunar/planetary exploration will also have to make do with less as well. The American Clementine mission to the Moon is an impressive indication of how cost effective and efficient modern state-of-the-art telerobotic systems can be compared with traditional space probes. Clementine sent back more pictures from the Moon than all previous lunar spacecraft combined despite being much smaller and cheaper. Consequently NASA has now proposed a number of similar "faster,cheaper,better" unmanned planetary missions using inexpensive high-tech concepts. The Luna-2001 proposal assumes that advanced unmanned probes rather than manned missions will do most of the initial exploration.
While Clementine (being part of the US Air Force's "Star Wars" program) was developed for military purposes, future post-cold war high-technology activities will depend on peaceful international cooperation for the common good of mankind. The major space nations are currently working on the International Space Station Alpha. After Alpha is completed in 2002, a return to the Moon would make sense as mankind's next major goal in space. Unlike Mars, the Moon can be explored using telepresence and "virtual reality" telerobotic systems - wide public participation would thus be possible. This "space exploration for the masses" approach would act as a powerful driver for the development of high-tech education, motivating young people and ensuring strong public support. Furthermore, landing astronauts on the Moon is much easier than going to Mars because the former is only three days away as opposed to one year. This means small (and eventually reusable-) spacecraft such as Luna-2001 can be used. Unmanned and manned lunar exploration could be carried out using current expendable rockets and future reusable launchers owned not only by the US and Russia but Europe and Japan as well. In contrast, manned Mars missions would probably require large, expendable craft launched on expensive (and non-existent) heavy-lift launch vehicles.
5.1 Manned vs. unmanned lunar exploration
While there are several compelling reasons to return to the Moon (astronomy, geology, physics, Earth observation etc.), recent advances in computer/robotics technology suggest that an advanced exploration program could be carried out using unmanned systems, at a fraction of the cost of sending humans to the Moon. Still, the fact remains that trained astronauts make far better and efficient explorers than do robots. Even if "robot geologists" eventually do most of the soil sampling surveys, humans will still be required for periodical maintenance of scientific equipment on the lunar surface.
To summarize, Luna-2001 is an inexpensive manned system whose main purpose is to complement rather than replace unmanned lunar exploration and manned activities in LEO. I believe that the Russian Space Agency, NASA -even ESA- could return to the Moon without having to spend vast sums of money or develop expensive new launcher technology. All that will be required is to summon the political will.