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User:ChenKB91/深空網路

< User:ChenKB91
深空網路
1988年NASA深空網路成立40週年紀念圖章
組織NASA / JPL
座標34°12′3″N 118°10′18″W / 34.20083°N 118.17167°W / 34.20083; -118.17167
設立1958年十月一日
網址deepspace.jpl.nasa.gov
望遠鏡
金石深空聯絡設施
美國加州巴爾斯多
馬德里深空聯絡設施
西班牙馬德里自治區羅夫來多-德查韋拉
坎培拉深空聯絡設施
澳大利亞提德賓比拉自然保留區

美國太空總署深空网络（英語：Deep Space Network）是NASA設置的一个用以聯絡航天器的全球網路設施，位于美国(加洲)、西班牙(马德里)和澳大利亚（坎培拉），用以為美國太空總署的行星際航行太空船提供通訊，也被用來執行射電天文學和雷达天文學對於太陽系和宇宙的观测，并對地球轨道上的人造衛星提供支持，是NASA噴射推進实验室 （JPL）的一部份。欧洲、俄罗斯、中国、印度和日本也有類似的網路。

一般資訊

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噴射推進實驗室內部的深空網路運作中心

DSN目前包含三个深空通信设施，以约120度的間隔围绕著地球。[1]分別為：

每個设施皆位于半山腰、碗状地形，以帮助阻擋无线电波干扰。[2] 考慮到地球的自轉，三座設施的地點以約120度的間距為繞著地球，目的是為了當地球自轉時，一座設施轉到背對著目標的一側，而無法進行觀測，但同時另一座設施便轉到了可進行觀測的一側，如此DSN便能24小時持續觀測目標。

NASA倚賴DSN以進行太阳系內的科學調查：可以双向溝通，地面基地可以引导並控制各种NASA的太空探測器，讓這些探測器可以傳回他們所收集的照片和數據資料。所有DSN天线皆具備高增益、附帶抛物面反射器的天线。這些天線盒數據傳送系統，使其能夠：

  • 自航天器获得遥測数据。
  • 向航天器发送指令。
  • 更新修改航天器內建软體。
  • 追蹤航天器的位置和速度。
  • 执行特長基线干涉测量。
  • 测量無線電波的變化，以進行無線電波科學實驗。
  • 收集科学数据。
  • 监测和控制整個系統的性能。

控制中心

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三座DSN設施的天線都直接連結到加州帕萨迪纳噴射推進實驗室內部的深空控制中心（也称为深空网络操作控制中心）。

在早期，控制中心內並没有所謂的永久设施，只有一个臨時搭建的，以好幾張桌子与和電話拼装在一个大房间電腦旁邊，以用來计算轨道。1961年七月，NASA开始建造永久设施：太空飞行操作设施（SFOF）。 该设施於1964年十月建造完成，並於1964年5月14日啟用。 一開始共有31座主控台，100個闭路电视摄像机和200多台显示器，用以支持游騎兵6號到9號，以及水手4號任務。[3]

目前，控制中心的工作人员在SFOF內监测並主導行动，并监側探測器的通訊品質，並掌管資料以提供給提供給通訊網路的使用者。此外，DSN的各個設施和操作中心，設有地面通訊設施，將三座設施的資料傳送給JPL的控制中心，再傳到世界各國的太空飛行控制中心，以及世界各地的科学家。

深空的定義

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從北極點上空向下看的示意圖，顯示DSN觀測站的位置及視角。當一台探測器距離地球超過30,000公里，它便隨時處於一個以上探測站的視野之中，並與之建立聯繫。

追踪太空深处的探測器相当不同于追踪低地球轨道上的探測器。深空飞行任务通常可見於大部分地球表面，並且可持續很長一段時間，因此只需要很少觀測站便可達成長時間追蹤的目的（DSN只有三个主要觀測站）。然而，由於這些探測器距離地球相當遙遠，這些觀測站則需要巨大的天线、非常灵敏的接收器，以及强大的訊號发射器，才能與探測器聯繫。

深空有數種不同的定義。根據一份1975年NASA的報告，DSN是設計來與「距離地球16000公里以上到太陽系中最遠的行星之間」 建立通訊[4]。JPL聲明，當一探測船位於距離地球30,000公里以上的高度，該探測船便總是位於至少一個觀測站的視野之內。[5]

國際電信聯盟保留了數個頻段，提供給深空網路及近地空間作通訊使用，他們定義：「深空」是指距離地球兩百萬公里以上的空間。

這個定義代表著月球任務，以及地球-太陽拉格朗日點的L1 和L2，都被认为是近地空间，不能使用国际电联的深空保留頻段。其他的拉格朗日点則不��到这条规则限制。

管理

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深空網路所屬於NASA，由JPL對其進行管理和運行，而後者是加州理工學院的一部分。行星際網路理事會（IND）由JPL的研究開發及運作所支撐，並管理JPL的內部計畫。The IND is considered to be JPL's focal point for all matters relating to telecommunications, interplanetary navigation, information systems, information technology, computing, software engineering, and other relevant technologies. While the IND is best known for its duties relating to the Deep Space Network, the organization also maintains the JPL Advanced Multi-Mission Operations System (AMMOS) and JPL's Institutional Computing and Information Services (ICIS).[6][7]

Harris Corporation is under a 5-year contract to JPL for the DSN's operations and maintenance. Harris has responsibility for managing the Goldstone complex, operating the DSOC, and for DSN operations, mission planning, operations engineering, and logistics.[8][9]

天線

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70 m antenna at Goldstone, California.

每座設施都包括至少四座深空終端機，裝載高敏感訊號接收器，以及大拋物面發射天線。他們分別為：

  • 一座直徑34米（112英尺）的高功效發射天線(HEF)
  • 兩座以上的34米（112英尺）波導天線（英语：Beam waveguide antennas）（哥德斯通有三座運行中，馬德里有兩座，坎培拉設有三座。）
  • 一座直徑26米（85英尺）發射天線
  • 一座直徑70米（230英尺）發射天線

Five of the 34-米（112-英尺） beam waveguide antennas were added to the system in the late 1990s. Three were located at Goldstone, and one each at Canberra and Madrid. A second 34-米（112-英尺） beam waveguide antenna (the network's sixth) was completed at the Madrid complex in 2004.

 

一般能力的DSN没有基本改变，因为一开始的星际旅行者的任务在1990年代初期。 然而，许多进步数字信号处理、排列和错误的修正已经通过的DSN。

The ability to array several antennas was incorporated to improve the data returned from the Voyager 2 Neptune encounter, and extensively used for the Galileo spacecraft, when the high-gain antenna did not deploy correctly.[10]

The DSN array currently available since the Galileo mission can link the 70-米（230-英尺） dish antenna at the Deep Space Network complex in Goldstone, California, with an identical antenna located in Australia, in addition to two 34-米（112-英尺） antennas at the Canberra complex. The California and Australia sites were used concurrently to pick up communications with Galileo.

Arraying of antennas within the three DSN locations is also used. For example, a 70-米（230-英尺） dish antenna can be arrayed with a 34-meter dish. For especially vital missions, like Voyager 2, the Canberra 70-米（230-英尺） dish can be arrayed with the Parkes Radio Telescope in Australia; and the Goldstone 70-meter dish can be arrayed with the Very Large Array of antennas in New Mexico. Also, two or more 34-米（112-英尺） dishes at one DSN location are commonly arrayed together.

All the stations are remotely operated from a centralized Signal Processing Center at each complex. These Centers house the electronic subsystems that point and control the antennas, receive and process the telemetry data, transmit commands, and generate the spacecraft navigation data. Once the data is processed at the complexes, it is transmitted to JPL for further processing and for distribution to science teams over a modern communications network.

Network limitations and challenges

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70m antenna in Robledo de Chavela, Community of Madrid, Spain

There are a number of limitations to the current DSN, and a number of challenges going forward.

  • The Deep Space Network is something of a misnomer, as there are no current plans, nor future plans, for exclusive communication satellites anywhere in space to handle multiparty, multi-mission use. All the transmitting and receiving equipment are Earth-based. Therefore, data transmission rates from/to any and all spacecrafts and space probes are severely constrained due to the distances from Earth.
  • The need to support "legacy" missions that have remained operational beyond their original lifetimes but are still returning scientific data. Programs such as Voyager have been operating long past their original mission termination date. They also need some of the largest antennas.
  • Replacing major components can cause problems as it can leave an antenna out of service for months at a time.
  • The older 70M & HEF antennas are reaching the end of their lives. At some point these will need to be replaced. The leading candidate for 70M replacement had been an array of smaller dishes,[11][12] but more recently the decision was taken to expand the provision of 34-meter (112 ft) BWG antennas at each complex to a total of 4.[13]
  • New spacecraft intended for missions beyond geocentric orbits are being equipped to use the beacon mode service, which allows such missions to operate without the DSN most of the time.

DSN and radio science

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Illustration of Juno and Jupiter. Juno is in a polar orbit that takes it close to Jupiter as it passes from north to south, getting a view of both poles. During the GS experiment it must point its antenna at the Deep Space Network on Earth to pick up a special signal sent from DSN.

The DSN forms one portion of the radio sciences experiment included on most deep space missions, where radio links between spacecraft and Earth are used to investigate planetary science, space physics and fundamental physics. The experiments include radio occultations, gravity field determination and celestial mechanics, bistatic scattering, doppler wind experiments, solar corona characterization, and tests of fundamental physics.[14]

For example, the Deep Space Network forms one component of the gravity science experiment on Juno. This includes special communication hardware on Juno and uses its communication system.[15] The DSN radiates a Ka-band uplink, which is picked up by Juno's Ka-Band communication system and then processed by a special communication box called KaTS, and then this new signal is sent back the DSN.[15] This allows the velocity of the spacecraft over time to be determined with a level of precision that allows a more accurate determination of the gravity field at planet Jupiter.[15][16]

See also

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参考文献

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  1. ^ Haynes, Robert. How We Get Pictures From Space (PDF). NASA Facts Revised (Washington, D.C.: U.S. Government Printing Office). 1987 [2013-09-19]. 
  2. ^ DSN:antennas. JPL, NASA. （原始内容存档于2011-04-11）. 
  3. ^ Deep Space Network Operations Control Center at the Jet Propulsion Laboratory, Pasadena, California. Picture Album of the DEEP SPACE NETWORK. NASA/JPL. [26 January 2014]. （原始内容存档于17 February 2013）. 
  4. ^ N. Renzetti. DSN Functions and Facilities (PDF). May 1975. 
  5. ^ Dr. Les Deutsch. NASA’s Deep Space Network: Big Antennas with a Big Job (PDF).  p. 25
  6. ^ IND Technology Program Overview. JPL. 
  7. ^ Weber, William J. Interplanetary Network Directorate. JPL. May 27, 2004. hdl:2014/40704.  Missing or empty |url= (help)
  8. ^ ITT Exelis selected for NASA Deep Space Network subcontract by Jet Propulsion Laboratory (新闻稿). ITT Exelis. 23 May 2013 [5 July 2016]. 
  9. ^ Gelles, David. Harris Corporation to Buy Defense Contractor Exelis for $4.7 Billion. DealBook. [2016-10-31]. 
  10. ^ Uplink-Downlink, Chapter 5, The Galileo Era – 1986–1996.
  11. ^ The Future Deep Space Network: An Array of Many Small Antennas. JPL. （原始内容存档于July 14, 2009）. 
  12. ^ Durgadas S. Bagri; Joseph I. Statman & Mark S. Gatti. Proposed Array-Based Deep Space Network for NASA (PDF). IEEE. 
  13. ^ DSN Aperature Enhancement Project. 
  14. ^ Radio Science. JPL. 
  15. ^ 15.0 15.1 15.2 [1]
  16. ^ [2]

[[Category:噴射推進實驗室]] [[Category:射电天文学]]

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