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The Mars express MARSIS sounder instrument

机译:火星快车MARSIS发声器

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摘要

The Mars advanced radar for subsurface and ionospheric sounding (MARSIS) on Mars Express is the first high-frequency sounding radar operating from orbital altitudes since the Apollo 17 Lunar Sounder flown in 1972. The radar operates from a highly elliptical orbit but acquires data only from altitudes lower than 1200 km. The periapsis altitude is 2501km. This radar has been succesfully operating since August 2005. The radar is a dual channel low-frequency sounder, operates between 1.3 and 5.5 MHz (MegaHertz) with wavelengths between 230 and 55 m in free space for subsurface sounding and between 0.1 and 5.5 MHz (wavelengths between 3000 and 55 m) for ionospheric sounding. The subsurface sounder can operate at one or two-frequency bands out of four available bands at either like or cross polarization. The subsurface sounding radar transmits radio frequency (RF) pulses of 250 (is duration through a 40 m dipole antenna. The return echoes are then converted to digital form and temporarily stored on board for some digital processing. A second antenna, a monopole, provides reception for the cross-polarized return and its data are processed by a second channel. This processing reduces the data rate produced by the instrument to rates allowed by the spacecraft communications channel. These processed returns are then sent to Earth by the telecommunications system on the spacecraft. The advances in digital data acquisition and processing, since 1972, have enabled this technique to be used in a compact spacecraft science instrument.. This sounder has obtained returns from several kilometers below the surface of the Mars. The ionospheric sounder operates at altitudes greater than 800 km in a mode that sweeps the entire 0.1 -5.5 MHz range. During ionospheric sounding, the transmitter sends a 91 us tone at 127 pulses per second rate. The frequency sweep takes 7.3 s to complete the 0.1-5.5 MHz range. Operational aspects of the instrument are described, including the selection of frequency bands and receive antenna selection, which are based on the expected solar zenith angle. The process of data take planning as well as data archiving are described. Results of both subsurface and ionospheric sounding are presented.
机译:自1972年“阿波罗17号”月球探空仪问世以来,火星快车上的火星用于地下和电离层探测的先进雷达(MARSIS)是第一架在轨道高度运行的高频探测雷达。该雷达在高度椭圆轨道上运行,但仅从海拔低于1200公里。根尖周高度为2501km。自2005年8月以来,该雷达已成功运行。该雷达是双通道低频测深仪,在1.3至5.5 MHz(MegaHertz)之间运行,在自由空间中的波长在230至55 m之间,用于地下探测,在0.1至5.5 MHz(波长在3000到55 m之间)进行电离层探测。地下探测仪可在四个可用频段中的一个或两个频段上以相似或交叉极化的方式工作。地下探测雷达通过40 m偶极天线发射250个射频脉冲(持续时间),然后将回波转换为数字形式,并临时存储在板上以进行一些数字处理。交叉极化回波的接收及其数据由第二个通道进行处理,这种处理将仪器产生的数据速率降低到航天器通信通道所允许的速率,然后这些处理过的回波由电信系统通过卫星发送到地球。自1972年以来,数字数据采集和处理技术的进步使该技术得以用于紧凑型航天器科学仪器中。该发声器从火星表面以下几公里处获得了回波。在整个0.1 -5.5 MHz范围内扫描的模式下,大于800 km。在电离层探测期间,发射器发送一个91我们以127脉冲/秒的速率音调。扫频需要7.3秒才能完成0.1-5.5 MHz的范围。描述了该仪器的操作方面,包括基于预期太阳天顶角的频段选择和接收天线选择。描述了数据获取计划以及数据归档的过程。提出了地下探测和电离层探测的结果。

著录项

  • 来源
    《Planetary and space science》 |2009年第15期|p.1975-1986|共12页
  • 作者单位

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Infocom Department, "La Sapienza" University of Rome, Italy;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Infocom Department, "La Sapienza" University of Rome, Italy;

    Alenia Aerospazio, Rome, Italy;

    Alenia Aerospazio, Rome, Italy;

    Infocom Department, "La Sapienza" University of Rome, Italy;

    Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA;

    Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    Laboratorie de Planetologie de Grenoble, 38041 Grenoble Cedex, France;

    Istituto di Fisica dello Spazio Interplanetario, Istituto Nazionale di Astrofisica, 00133 Rome, Italy;

    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA;

    University of Bochum, Bochum, Germany;

    Alenia Aerospazio, Rome, Italy;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    subsurface sounder; ionospheric sounder; ground penetrating radar; sounder; mars;

    机译:地下测深仪;电离层测深仪;探地雷达;海底;火星;

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