The Long Term Temperature Variation in the Lunar Subsurface

Introduction: Lunar surface heat flow values were measured directly during the Apollo missions. These experiments were carried out on Apollo 15 and 17 for about six years between July 7, 1971 and September 30, 1977. The heat flow values derived from these two measurement sites were 21 mW/m2 and 14 mW/m2 respectively [1]. Langseth et al. concluded the repre-sentative global lunar heat flow to be around 18 mW/m2 based on approximately the first 3 years of data until the end of the 1974 (see Figure 1). Recently, Saito et al. (2006) succeeded in archiving the heat flow data from March 1 1976 until September 30th 1977 [2]. These data are very useful for identify-ing this very long-term variation because we could extend the period of data almost by a factor of two (from 3 years to 6 years) compared to the data ar-chived previously. Because an anomaly had occurred on April 28th, 1976 on the Apollo 15 experiment, the data of Apollo 15 could not be expanded. Therefore, the data obtained by Apollo 17 were used for long term analysis

Re-Analysis of HFT Data Using the Apollo Lunar Surface Gravimeter Data

Introduction: The Apollo Passive Seismic Experiment (PSE) was carried out on Apollo 12, 14, 15 and 16. Network observations of four seismic stations were performed for five years from 1972 to 1977. The PSE was a successful mission that informed us of the lunar crustal thickness and seismic velocity structure of the Moon from direct observations of the lunar interior (e.g. [1]). However, the paucity of seismic stations and the limited number of usable seismic events have been a major problem of lunar seismology. An additional observation point enables us to expand the network and the observable area will expand accordingly. Using a data set called the Work Tape, Kawamura et al. (2008) [2] showed that the Lunar Surface Gravimeter (LSG) on Apollo 17 functioned as a seismograph. With this additional seismic station, we tried the first seismic analysis using the LSG data

The Lunar Surface Gravimeter as a Lunar Seismograph

Introduction: The primary objective for the Lunar Surface Gravimeter (LSG) on Apollo 17 was to search for gravitational waves, but it failed in detecting them [1]. When the instrument was deployed on the Moon, the sensor beam could not be balanced in the proper equilibrium position. Consequently, the LSG was not able to function as originally designed. Lauderdale and Eichelman (1974) [1] concluded that “no provision has been made to supply data from the experiment to the National Space Science Data Center.” However, it was reported in Giganti et al. (1977) [2] that though they had not detected gravitational waves, after a series of reconfigurations the beam was recentered and the LSG gathered useful data. Besides the observation of gravitational waves, the LSG was also designed to observe seismic signals and tidal deformations [3]. According to Giganti et al. (1977) [2] LSG’s sensitivity covered the frequency range from 1~16Hz (Fig.1). There are several types of moonquakes reported, deep moonquakes, meteorite impacts, and high frequency teleseismic (HFT). Each of the moonquakes is known to have a resonant frequency around 1Hz and in addition, HFT has a predominant frequency around 10 Hz [4]. Therefore it is likely that the LSG was detecting the seismic events on the Moon. However, the LSG data have not been analyzed from a seismological point of view

Lost Apollo heat flow data suggest a different lunar bulk composition

Lunar surface heat flow values were measured on the Apollo missions between 1971 and 1977. However, the late-term data have been lost. We succeeded in archiving the data after March 1, 1976. We will introduce the new set of archived data

How to avoid potential pitfalls in recurrence plot based data analysis

Recurrence plots and recurrence quantification analysis have become popular in the last two decades. Recurrence based methods have on the one hand a deep foundation in the theory of dynamical systems and are on the other hand powerful tools for the investigation of a variety of problems. The increasing interest encompasses the growing risk of misuse and uncritical application of these methods. Therefore, we point out potential problems and pitfalls related to different aspects of the application of recurrence plots and recurrence quantification analysis

Re-determination of deep moonquake sources using the Apollo 17 lunar surface gravimeter

We performed the first seismic analysis of deep moonquakes using the Apollo 17 Lunar Surface Gravimeter. We redetermined the seismic source of the deep moonquakes and evaluated the contribution of the LSG

Recurrence-based time series analysis by means of complex network methods

Complex networks are an important paradigm of modern complex systems sciences which allows quantitatively assessing the structural properties of systems composed of different interacting entities. During the last years, intensive efforts have been spent on applying network-based concepts also for the analysis of dynamically relevant higher-order statistical properties of time series. Notably, many corresponding approaches are closely related with the concept of recurrence in phase space. In this paper, we review recent methodological advances in time series analysis based on complex networks, with a special emphasis on methods founded on recurrence plots. The potentials and limitations of the individual methods are discussed and illustrated for paradigmatic examples of dynamical systems as well as for real-world time series. Complex network measures are shown to provide information about structural features of dynamical systems that are complementary to those characterized by other methods of time series analysis and, hence, substantially enrich the knowledge gathered from other existing (linear as well as nonlinear) approaches.Comment: To be published in International Journal of Bifurcation and Chaos (2011