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The accumulation rate is a key parameter in computing the mass balance of glaciers and ice sheets to estimate sea level rise. A shallow-layers-detection ice sounding radar (SLDISR) is developed to measure the accumulation rate and shape of near-surface internal layers with high resolution. With a transmitting frequency from 500 to 2000 MHz, this frequency-modulated continuous wave (FMCW) radar provides a range resolution of about 16 cm in free space by using a Hanning window and a penetrating depth about 150 m under polar ice. The spectral analysis and coherent integration techniques are used to obtain a high processing gain and to improve the signal-to-noise ratio of the system. A phase-locked loop with wideband yttrium iron garnet (YIG) oscillator is applied to generate a sweeping chirp signal as an input source for the transmitter. A stable, low-frequency reference chirp signal is generated with a direct digital synthesizer (DDS) integrated in field-programmable gate array (FPGA). To reduce the high-speed requirement to the analog-to-digital converter (ADC), dechirp technology is adopted at the RF section of the receiver. The implementation of the digital unit is based on an FPGA chip. The designed radar has been successfully deployed in Antarctica during the 31st Chinese Antarctic Research Expedition (CHINARE 31) and CHINARE 33, mainly over the East Antarctic Ice Sheet (EAIS). The echograms indicate the effectiveness of the radar system on detecting clear internal reflecting horizons (IRHs) over ice sheets.

Sampling return in Chang'E-5 (CE-5) mission is the third phase of three strategic steps of China's lunar program. The three strategic steps are orbiting, landing, and returning. The sampling and drilling device is mounted on the Lander. One task of the CE-5 Lunar Regolith Penetrating Radar (LRPR) is to provide information support for the drilling and sampling device. This article introduces the scientific objectives of CE-5 LRPR and the difference with Chang'E-3 lunar penetrating radar. The system design, working principle, imaging, and calibration methods of LRPR are the highlight. Considering that the Lander is stationary, and its bottom is about 90 cm from the lunar surface, an antenna array is adopted to probe the subsurface structure and the regolith thickness for supporting the drilling. The design uses a pre-amplifier circuit to increase the dynamic range of the whole system, which enhances the detection effect of shallow lunar soil structure. For verifying the probing ability of LRPR, the marble slabs, metal balls, and stones are buried in the volcanic ash pool in advance for detection and verification. The pre-stack Kirchhoff depth migration imaging method is adopted to identify the burial depth and thickness of the target. The verification results meet the task requirements.

The Tianwen-1 of China is expected to land and explore on the planet Mars in May 2021, carrying a Mars Rover-mounted Subsurface Penetrating Radar (RoSPR) system. A VHF band ultra-wideband (UWB) monopole antenna integrated on the Mars Rover, and described in this paper, has been designed for the subsurface exploration of Mars tens of meters deep. Conventional antenna design methods usually prove difficult in taking into account several key parameters such as miniaturization, broadband characteristics and radiation efficiency. Moreover, there is almost no special research on the reliability of antennas. For this purpose, a miniaturized air-coupled monopole antenna integrated with the Mars Rover has been designed. The overall length of the antenna is 0.13 λ at the lowest operating frequency. In addition, the classical Wu–King profile is improved, which not only satisfies the operating bandwidth of the antenna, but also increases the gain by 3–4 dB. In the design, the innovative application of planar embedded resistance greatly enhances the reliability of the antenna and thereby ensures that the antenna can work on Mars for a long term. This is the first application of this antenna design method in the aerospace field. Because it is difficult to test the low-frequency antenna accurately, a 1:4 scale model of the antenna and Rover is fabricated to equivalently measure the radiation characteristics of the antenna. Furthermore, the performance and practicability of the antenna and radar system are verified on the glacier.

This paper presents the ice thickness, fine resolution internal reflecting horizons (IRHs), and distinct bottom topography measurements of Chinese Kunlun Station and Grove Mountains, Antarctica, derived from sounding these glaciers with a high-resolution radar. To enable the development of next-generation ice-sheet models, we need information on IRHs, bottom topography, and basal conditions. To this end, we performed measurements with the progressively improved ice-sounding radar system, currently known as the high-resolution ice-sounding radar developed by the Key Laboratory of Electromagnetic Radiation and Sensing Technology of Institute of Electronics, Chinese Academy of Sciences, Beijing, China. We processed the collected data using focused synthetic aperture radar (SAR) algorithm named the modified range migration algorithm using curvelets and the modified nonlinear chirp scaling algorithm to improve radar sensitivity and reduce along-track surface clutter. Representative results from selected transects indicate that we successfully sounded 3-km-thick ice with a fine resolution of 0.75 m. In this paper, we provide a brief description of the radar system, discuss the focused SAR processing algorithms, and provide sample results to demonstrate the successful sounding of the ice sheet in Antarctica.

The Chang&rsquo, e-5 lunar exploration mission of China is equipped with a Lunar Regolith Penetrating Radar (LRPR) for measuring the thickness and structures of the lunar regolith in the landing area. Since the LRPR is stationary, an ultra-wideband multiple-input multiple-output (MIMO) array is designed as a replacement for conventional mobile subsurface probing systems. The MIMO array, with 12 antenna elements and a switch matrix, operates in the frequency band from 1.0 to 4.75 GHz. In this work, the design and layout of the antenna elements were optimized with respect to the lander. To this end, the antenna elements were designed as miniaturized Vivaldi antennas with quarter elliptical slots (i.e., quarter elliptical slotted antenna, or QESA). QESAs are significantly small while being able to mitigate the impact of the lander on antenna electrical performances. QESAs also have a wide operating bandwidth, flat gain, and excellent time domain characteristics. In addition, a high-temperature resistant ultra-light radome with high transmissivity is designed to protect the external antenna array. After calibration, the MIMO array is used to detect targets embedded in volcanic ash. The detection depth reaches 2.5 m, and the detection effect is good.

Lunar Penetrating Radar (LPR) is one of the important scientific instruments onboard the Chang'e-3 spacecraft. Its scientific goals are the mapping of lunar regolith and detection of subsurface geologic structures. This paper describes the goals of the mission, as well as the basic principles, design, composition and achievements of the LPR. Finally, experiments on a glacier and the lunar surface are analyzed.