Catching Some Z's: Selene Survives a Lunar Night

After spending a week on the moon, Selene will move onto her next task, surviving a lunar night. A lunar day consists of about 29 days--roughly a month on an Earth calendar. For about half of that time, a portion of the moon, in this case where Selene is located, is facing away from the sun. This is called a lunar night, and it is one of the toughest obstacles she will face. During this lunar night, temperatures on the surface of the moon drop to about - 167.7o C [15] making for a frigid, icy, and bitterly cold two weeks. To combat these conditions, Selene will be equipped with several special features specifically designed for lasting the lunar night. In order to keep some of the heat trapped within the carbon fiber body, the rover will be fitted with thermal blankets on her exterior. A thermal blanket is made of a thin sheet of metallic foil spaced out with insular fabrics [16]. In most of these blankets, the coating is aluminum vapor, distributed by a vacuum. The space blanket is not only beneficial for preserving heat for the rover, but also because it is practically weightless and will not hinder the rover in any other way. Another possible heat source was radioactive materials. Some of these materials, such as plutonium-238 or plutonium- 239, have been used on certain Mars expeditions. However, they would require a generator which would add to the weight of the rover and require too much power to operate. The use of aerogels [17] on the rover was also considered, although it was dismissed because the moon's environment lacks air [10]. Therefore, through an examination of all of the heating options, thermal blankets were found to be the best fit for this mission: surviving a lunar night.

However, these materials and provisions are not sufficient on their own. In addition to thermal blankets, several aspects of Selene's nocturnal activity will be used as methods to protect her from the intensity of a lunar night. The first method is rather simple: to keep the equipment that requires warmth together and only heat that portion of Selene. This will conserve more energy than trying to heat multiple parts of the rover. Furthermore, the rover will start up periodically and travel a certain distance before shutting down again. This will prevent the motor and gears from freezing or sticking due to disuse. This idea was inspired by the advice of car dealers, who tell their customers to drive their new vehicles at least once every few weeks. This method will also conserve power that will be scarce during the lunar night as the rover will be running only on battery power. These strategies will help Selene complete the near impossible task of surviving a lunar night.


Looking to the Future In conclusion, Selene will complete the required tasks along with some of the bonus tasks specified by the Google Lunar X Prize Competition. These responsibilities include sending a Mooncast, consisting of at least 1 GB of information back to Earth; recording High Definition (HD) videos; photographing a 360 degree image of the surface of the Moon; and taking a self-portrait while on the Moon [2]. The Mooncast will be made possible through Selene’s various technologies such as her stereo pairs of cameras and omniantenna. With the help of six wheels and a combination of solar and battery power, the rover will travel a minimum of 500 meters. While coping with the challenge of surviving a lunar night, a bonus requirement, Selene will employ the use of thermal blankets. She will also be taking on the challenge of imaging man-made artifacts, such as debris from the Apollo Mission, when she lands in the Sea of Tranquility. The information Selene returns will hopefully inspire other similar missions just as prior missions have inspired us. Lunar exploration is full of possibilities and should not be ignored. As we look to the future, we hope to find more opportunities to take an active role in lunar exploration.