Characterizing the Performance of Haleakala as a Ground Site for Laser Communications
Characterizing the Performance of Haleakala as a Ground Site for Laser Communications
复制标题
描述哈雷阿卡拉作为激光通信地面站点的性能
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Alliss
中科院分区：
文献类型：
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作者：
B. Felton;R. Alliss
自近60年前卫星通信开始以来，无线电频率（RF）信号一直是唯一和成功地与航天器通信的依赖。但是，特派团现在要求更高的数据速率以满足其数据收集需要。为了应付这一需要，若干组织已开始采取步骤，通过发展激光通信终端机和未来特派团的业务概念来增加未来特派团的数据能力。例如，2013年秋季，NASA的月球激光通信演示（LLCD）成功地演示了与绕月轨道运行的LADEE卫星之间的高数据速率通信链路。下一步，激光通信中继演示（LCRD）将以LLCD获得的经验为基础，从地球同步轨道上对自由空间光通信（FSOC）进行多年测试。这些任务的规划包括确定候选地面站位置，量化大气对数据链的影响，以及制定业务概念，以减轻由于云层、湍流和气溶胶造成的传输损失。由于空对地光通信受到云层、湍流和其他大气现象的不利影响，因此研究大气对通信链路的影响非常重要。为了支持这一点，诺斯罗普·格鲁曼公司正在领导一项运动，测量和模拟大气对哈雷阿卡拉山顶地面站和地球静止轨道卫星之间连接的影响。这项工作的一部分包括使用天气研究与预报（WRF）模式的修改版本来生成光学湍流参数的长期气候学，以及在运行期间从地面站到卫星的视距（LOS）上的大气特征，以用作链路诊断工具。虽然地面仪器可用于测量沿整个LOS综合的湍流的影响，但它们通常不能用于识别湍流的垂直结构。在这项工作中，WRF被用于生成行星边界层和自由大气中Cn和其他大气参数的三维表示。这允许沿平均海平面以上20公里以下LOS的整个部分的Cn特征，以及沿LOS的弗里德相干长度（r0）和其他观测参数的估计。此外，还将部署一套地面传感器，包括气象站、全天空成像仪和ceilometer。他们的测量结果将与世界资源基金的产出相结合，以支持任务规划和制定减轻链路中断的业务概念。特别是，现场云数据将与多光谱地球静止卫星图像和WRF模式探测一起使用，以表征和预测云高度和云对Haleakala山顶的侵蚀。在这项工作中，WRF模型被配置为在一个区域以1公里的水平分辨率运行，该区域包括夏威夷大岛和毛伊岛的哈雷阿卡拉的主要天文台。这项工作的结果将用于量化大气对FSOC通信的影响，诊断链路中断，并制定大气缓解策略。
Radio Frequency (RF) signals have been relied on exclusively and successfully to communicate with spacecraft since satellite communications began nearly 60 years ago. However, missions now demand higher data rates to meet their data collection requirements. In response to this need, several organizations have begun to take steps to increase the data capacity of future missions by developing laser communications terminals and operational concepts for future missions. For example, NASA’s Lunar Laser Communications Demonstration (LLCD) successfully demonstrated high data rate communications links to and from the LADEE satellite orbiting the moon during the Fall of 2013. As a next step, the Laser Communication Relay Demonstration (LCRD) will build upon the experience gained from LLCD and perform multi-year testing of Free-Space Optical Communications (FSOC) from geosynchronous orbit. Planning for these missions has included identifying candidate ground station locations, quantifying the impacts of the atmosphere on the data links, and developing operational concepts for mitigating transmission losses due to clouds, turbulence, and aerosols. Since space-to-ground optical communications are adversely affected by the presence of clouds, turbulence, and other atmospheric phenomena, it is important to study the effects of the atmosphere on the communications link. To support this, Northrop Grumman is leading a campaign to measure and model the atmospheric effects on the link between a ground station on the summit of Haleakala and a satellite in geostationary orbit. Part of this effort involves using a modified version of the Weather Research & Forecast (WRF) model to generate long-term climatologies of optical turbulence parameters as well as to characterize the atmosphere along line-of-sight (LOS) from the ground station to the satellite during operations to be used as a link diagnostic tool. While ground-based instruments can be used to measure the effects of turbulence integrated along the entire LOS, they cannot generally be used to identify the vertical structure of turbulence. In this work, WRF is used to generate a three-dimensional representation of Cn and other atmospheric parameters in both the planetary boundary layer and the free atmosphere. This allows for the characterization of Cn along the entire portion of the LOS below 20-km above mean sea level along with estimates of the Fried Coherence length (r0) and other seeing parameters along the LOS. In addition, a suite of ground-based sensors will be deployed, including a meteorological station, a whole-sky imager, and a ceilometer. Their measurements will be combined with output from WRF to support mission planning and the development of operational concepts for mitigating link outages. In particular, the in situ cloud data will be used along with multispectral geostationary satellite imagery and WRF model soundings to characterize and predict cloud heights and cloud encroachment over the summit of Haleakala. For this work, the WRF model is configured to run at 1-km horizontal resolution over a domain that includes the major observatories on the Big Island of Hawaii as well as Haleakala on Maui. Results from this work will be used to quantify the effects of the atmosphere on FSOC communications, diagnose link disruptions, and to develop atmospheric mitigation strategies.