The spacecraft consists of a payload and bus. Before sizing the lander, the payload mass and its envelope have to be defined.

Simple Sizing of the Lander

Figure 4-27 shows an overview of the lander system.

Table 4-3 shows the basic charasteristics of the payload.

Appendix C summarizes mass and dimension calculations.

Lander Outline

As shown in Figure 4-28, the lander consists of two elements. The first element consists mainly of a propulsion subsystem and landing gear. The second consists of a payload container and avionics equipment. The container area consists of two floors. The first floor contains four rovers and a media vehicle, while the second contains six rovers.

After separation from the launcher, the lander will use the main engine to aquire the necessary deltaV. During lunar approach, high precision retroburns will be commanded from Mission Control to position the lander within a 1 km radius of the Apollo 17 landing site. After the lander has deployed its solar panels, ground control investigates the lunar environment with the on-board cameras to find an adequate direction for rover deployment. Some directions may not be suitable to deploy the rovers because there may be obstacles such as rocks and small craters. The container area will rotate around the lander's center axis to point in the selected direction. The lander then deploys the slider along which the rovers will descend to the Lunar surface.

Simple Sizing of the Lander

The fairings of many current launchers are normally about 4 m in diameter. In order to be installed in a current fairing, the lander width is assumed to be 2.5 m (square lander cross-section). From the mass and the density of propellant, the propellant tank dimensions are calculated. The shape of the tanks is assumed to be spherical Table 4-4 shows the dimension of the propellant tanks. The lander size is consistent with the propellant volume.

The width of each rover is 0.5 m (maximum). As shown in Figure 4-29, four rovers can be lined in one row, including spatial margins, along the 2.5 m width of the lander. Four rovers and the media vehicle on the first floor fill two rows. The six rovers on the second floor also fill two rows.

Launcher

From the mass of the spacecraft, a launcher is selected. The total mass of the launcher's payload (lander, media vehicle, and rovers) is 1.6 tons.

The lander is light enough to be carried by current medium launchers, such as the Delta 2 or the Ariane 4 family. Since performance data was almost exclusively available on LEO/GTO capability, the baseline design of the lander looks at a trans-lunar injection from GTO. Due to the fact that the deltaV to the Moon from GTO is approximately 700 m/s higher than for a spacecraft that is directly inserted to the Moon by the launcher, this is a worst case assumption. Spacecraft cost and mass will decrease significantly if the launcher provides the injection. The reliability is reflected by the ratio of successful flights versus previous flights. For launcher types with a small number of launches, the reliability of the launcher family was also taken into account. An interesting point here is the high dependency of the reliability of the Molniya launcher on the launch site (Baikonur versus Plesetsk).

The table was compiled with the most recent information available. The ratio of average cost divided by reliability reflects success rate and is approximately what can be expected for launch cost plus launch insurance. The main conclusion we can reach from analysis of this table is that it is feasible to bring the lunar lander proposed here into space for 30 to 50-million US$. Again, in this report the worst case was chosen as baseline for the cost calculation (50-million US$).

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