The real challenges of a Lunar Landing include the extreme temperature swings on the Moon's surface (-173 C to +127 C at the Equator). Safe operation of the Micro-Space system will require landing about 24 hours after local sunrise on the Moon (with the Sun 15 degrees above the horizon). This will produce a surface temperature of about + 8 C (in the equatorial zone). Our spacecraft will cool slowly, and soon be warming up as the Sun climbs higher. The low sun angle during landing will produce good topographic shadows that will help to identify rocks to avoid while landing, and optimize the performance of optical Sun sensors and Horizon sensors to orient the Lander. A slightly later landing will be OK since the landing pads can easily be made heat tolerant.

Twenty four hours after landing the Moon's surface will have heated to about +58C (the Sun 30 degrees above the horizon). The Lander and Rover will be warming up. The use of white paint on these craft will reduce their solar heating. Gold plated or aluminized foil can reduce the absorption of Infrared radiated from the Moon's surface, but it would be very difficult to continue operation through Lunar noon (+127 C surface temperature).

Consideration of this temperature range pushed us to research the “Radio Emission Temperature” of the Moon, since its wide surface temperature range can impact the noise level for radio communications. Available data shows that the effective radio surface is at some depth, and that the radio temperature shows a much smaller, delayed swing. We discussed this in the last Micro-Space posting.

Note for the “esoteric” part of the prior discussion that widely spaced radio antennas in an array have the same mathematical effect as widely spaced samples (beyond the Nyquist Criteria) in signal processing. The “Aliases” produced in signal processing are like the “side lobes” in antenna theory. Regularly spaced samples produce discrete aliases, often related to harmonics of the desired signal. The same is true of the spaced antennas. Both can be moved to pseudo random spacing which increases the number of aliases, but decreases their amplitude.