火衛一計畫

火衛一計畫 (Фобос, Fobos) 是一項蘇聯太空計劃，該計畫由兩顆無人空間探測器組成，以探測火星及其的衛星(火衛一和火衛二)。火衛一1號和火衛一2號分別在1988年7月7日和1988年7月12日使用質子K型運載火箭發射。

火衛一1號在前往火星的途中失聯。火衛一2號成功進入繞火軌道，但在著陸器著陸之前失去聯繫。兩個探測器使用了全新的探測器設計，繼承了1975 年至 1985 年期間金星計畫使用的4MV型探測器，以及維加1號和維加2號哈雷彗星任務中使用的5VK型探測器。每個探測器的質量為2600公斤（安裝入軌機動部件後質量為6220公斤，為2011年發射的福布斯-土壤之前的最重深空探測器）。

這次計畫除了蘇聯之外，還與其他14個國家合作，其中包括瑞典、瑞士、奧地利、法國、西德和美國等國（美國貢獻了其深空網路來追蹤這對探測器）。

## 目的

The objectives of the Phobos missions were to:

- conduct studies of the interplanetary environment;
- perform observations of the Sun;
- characterize the plasma environment in the Martian vicinity;
- conduct surface and atmospheric studies of Mars; and,
- study the surface composition of the Martian satellite Phobos.

## 設計

The main section of the spacecraft consisted of a pressurized toroidal electronics section, surrounding a modular cylindrical experiment section. Below these were mounted four spherical tanks (the Fregat stage) containing hydrazine for attitude control and, after the main propulsion module was to be jettisoned, orbit adjustment. A total of 28 thrusters (twenty-four 50 N thrusters and four 10 N thrusters) were mounted on the spherical tanks, with additional thrusters mounted on the spacecraft body and solar panels. Attitude was maintained through the use of a three-axis control system, with pointing maintained with Sun and star sensors.

## 火衛一1號

火衛一1號一開始運作正常，但在前往火星幾週後，原定於1988年9月2日的聯繫卻失敗。控制人員與探測器失聯，事後被查明是因為在1988年8月29日或30日上傳的軟體發生故障，姿態推進器停止運作。導致太陽能板無法再對準太陽，從而耗盡了電池電量。

Software instructions to turn off the probe's attitude control, normally a fatal operation, were part of a routine used when testing the spacecraft on the ground. Normally this routine would be removed before launch. However, the software was coded in PROMs, and so removing the test code would have required removing and replacing the entire computer. Because of time pressure from the impending launch, engineers decided to leave the command sequence in, though it should never be used. However, a single-character error in constructing an upload sequence resulted in the command executing, with subsequent loss of the spacecraft.

## 火衛一2號

火衛一2號在1988年7月12日使用質子K型運載火箭發射，並於1989年1月29日進入火星軌道。1989年1月29日，火衛一2號巡航階段和火星軌道插入階段成功，並收集了有關太陽、行星際介質、火星和火衛一的數據。火衛一2號號探測了火星表面和大氣層及傳回了37張解析度高達 40 米的火衛一圖像，火衛一2號在準備著陸器著陸之前失去聯繫。

## 系統和科學儀器

Phobos probes carried several instruments: solar x-ray and ultraviolet telescopes, a neutron spectrometer and the Grunt radar experiment designed to study the surface relief of Phobos.

The lander had an x-ray/alpha spectrometer to provide information on the chemical element composition of the surface of Phobos, a seismometer to determine the internal structure of Phobos, and the "Razrez" penetrator with temperature sensors and an accelerometer for testing the physical and mechanical properties of the surface.

The Phobos 2 infrared spectrometer (ISM) obtained 45000 spectra in the near infrared (from 0.75 to 3.2 μm) in the equatorial areas of Mars, with a spatial resolution ranging from 7 to 25 km, and 400 spectra of Phobos at 700 m resolution. These observations made it possible to retrieve the first mineralogical maps of the planet and its satellite, and to study the atmosphere of Mars. ISM was developed at IAS and DESPA (Paris Observatory) with support from CNES.

List of instruments:

- "VSK" TV imaging system
- PROP-F "hopping" lander. Only carried by Phobos 2.
- ARS-FP automatic X-ray fluorescence spectrometer
- ferroprobe magnetometer
- Kappameter magnetic permeability / susceptibility sensor
- gravimeter
- temperature sensors
- BISIN conductometer / tiltmeter
- mechanical sensors (penetrometer, UIU accelerometer, sensors on hopping mechanism)
- "DAS" (long-lived autonomous station) lander
- TV camera
- ALPHA-X Alpha-Proton-X-Ray Spectrometer
- LIBRATION Sun sensor (also known as STENOPEE)
- Seismometer
- RAZREZ anchor penetrometer
- Celestial mechanics experiment
- "ISM" thermal infrared spectrometer/radiometer - 1–2 km resolution
- near-infrared imaging spectrometer
- thermal imaging camera; magnetometers
- gamma-ray spectrometers
- X-ray telescope
- radiation detectors
- radar and laser altimeters
- Lima-D laser experiment - designed to vaporise material from the Phobos surface for chemical analysis by a mass spectrometer
- Automatic Space Plasma Experiment with Rotating Analyzer (ASPERA), an electron spectrometer and ion mass analyser from the Swedish Institute of Space Physics.
- "Grunt" imaging radar - Only carried by Phobos 1

## 後續

本計畫的設計方案後來再次被用於延期已久的火星96任務（探測目標改為火星），但該任務最終因運載火箭D2組級點火失敗而告終。此外，同樣旨在探測火衛一的福布斯-土壤任務也在2011年失敗。迄今為止，還沒有探測器能夠完全成功地抵達火衛一。

## 參考資料

- Articles in Nature 341 (1989) pages 581 - 619
- Phobos Project Information (NASA NSSDC)
- Fobos 1F
- ISM - Phobos-2 archive
- The Airport Terminal - also known as Mariner 9 #4209-75

## 外部連結

- High quality processed images from the Phobos 2 mission
- Phobos mission images from the Space Research Institute (IKI)
- Raw image data from the Phobos 2 ISM infrared instrument
- What we are searching for on Phobos - an article on the Phobos program at the Web site of the Russian Space Agency
- Another site with processed images from the Soviet Phobos 2 mission