Vega 2

This spacecraft mission combined a Venus swingby and a Comet Halley flyby. Two identical spacecraft, Vega 1 and Vega 2, were launched December 15 and 21, 1984, respectively. After carrying Venus entry probes to the vicinity of Venus (arrival and deployment of probes were scheduled for June 11-15, 1985), the two spacecraft were retargetted using Venus gravity field assistance to intercept Comet Halley in March 1986. The first spacecraft encountered Comet Halley on March 6, 1986, and the second three days later. The flyby velocity was 77.7 km/s. Although the spacecraft could be targetted with a precision of 100 km, the position of the spacecraft relative to the comet nucleus was estimated to be known only to within a few thousand kilometers. This, together with the problem of dust protection, led to estimated flyby distances of 10,000 km for the first spacecraft and 3000 km for the second.

The spacecraft was three-axis stabilized. Its main features were large solar panels, a high-gain antenna dish, and an automatic pointing platform carrying those experiments that required pointing at the comet nucleus. The automatic platform could rotate through + or -110 deg and + or -40 deg in two perpendicular directions with a pointing accuracy of 5 arc-min and a stability of 1 arc-min/s. It carried the narrow- and the wide-angle camera, the three-channel spectrometer, and the infrared sounder. All other experiments were body-mounted, with the exception of two magnetometer sensors mounted on a 2-m boom and various plasma probes and plasma wavw analyzers mounted on a 5-m boom. The total scientificpayload weighed 125 kg and had a data rate of 65 kbs in fast telemetry mode for encounter. There was also a slow telemetry mode for the cruise mode. The comet-encounter science data-take was from 2.5 h before until 0.5 h after the closest approach, with several periods of data-take before and after, each lasting about 2 h. Continuous coverage for plasma and dust instruments was provided by an onboard memory (5-megabit tape recorder). The spacecraft was shielded from hypervelocity dust impacts by a shield consisting of a 100-micrometer multilayer sheet 20 to 30 cm from the spacecraft, and a 1-mm Al sheet 5 to 10 cm from the spacecraft. Approximately half of the VEGA spacecraft was devoted to the Halley module, and half to the Venus lander package. The total scientific payload weight was 144.3 kg.

The Venus package consisted of a sphere 240 cm in diameter, which separated two days before arrival at Venus and entered the planet's atmosphere on an inclined path, without active maneuvers, as was done on previous Venera missions. The lander probe was identical to those of Venera 9 through 14 and similarly had two objectives, the study of the atmosphere and the study of the superficial crust. In addition to temperature and pressure measuring instruments, the descent probe carried a UV spectrometer for measurement of minor atmospheric constituents, an instrument dedicated to measurement of the concentration of H2O, and other instruments for determination of the chemical composition of the condensed phase: a gas-phase chromatograph; an X-ray spectrometer observing the fluorescence of grains or drops; and a mass spectrograph measuring the chemical composition of the grains or drops. The X-ray spectrometer separated the grains according to their sizes using a laser imaging device, while the mass spectrograph separated them according to their sizes using an aerodynamical inertial separator. After landing, a small surface sample near the probe was to be analyzed by gamma spectroscopy and X-ray fluorescence. The UV spectrometer, the mass spectrograph, and the pressure- and temperature-measuring instruments were developed in cooperation between French and Soviet investigators.

In addition to the lander probe, a constant-pressure instrumented balloon aerostat was deployed after entry into the atmosphere from the upper heat protection hemisphere. It floated at approximately 50 km altitude in the middle, most active layer of the Venus three-tiered cloud system. Data from the balloon instruments were transmitted directly to Earth for the 47-hr lifetime of the mission.

此次航天器任务结合了对金星的重力助推和哈雷彗星的掠过观测。两艘完全相同的航天器，分别是维加1号和维加2号，分别于1984年12月15日和21日发射。在将金星进入探测器运送到金星附近（探测器的到达和部署计划于1985年6月11日至15日）后，两艘航天器利用金星引力场辅助进行重新定位，以便在1986年3月拦截哈雷彗星。第一艘航天器于1986年3月6日遇到哈雷彗星，第二艘则是在三天后。掠过速度为77.7公里/秒。尽管航天器的定位精度可达100公里，但相对于彗星核的位置估计仅知其大致在数千公里范围内。这，连同尘埃防护问题，导致估计的掠过距离为第一艘航天器约10000公里，第二艘约3000公里。

航天器采用三轴稳定。其主要特点包括大型的太阳能帆板、高增益天线碟以及一个自动对准平台，该平台搭载了对彗星核进行对准所需的实验。自动平台可以在两个垂直方向上旋转+/-110度和+/-40度，具有5角分对准精度和1角分/秒的稳定性。它携带了窄角和广角相机、三通道光谱仪和红外声音探测器。所有其他实验均为机身安装，除了两个磁力计传感器安装在2米长的杆上，以及各种等离子体探测器和等离子体波分析仪安装在5米长的杆上。总科学有效载荷重量为125公斤，在快速遥测模式下数据传输速率为65千比特每秒。此外，还有一种慢速遥测模式用于巡航模式。彗星遭遇的科学数据采集从接近前2.5小时开始，直到接近后0.5小时结束，前后各进行了几次约2小时的数据采集。等离子体和尘埃仪器由机载存储器（5兆比特磁带录音机）提供连续覆盖。航天器通过位于航天器20至30厘米处的100微米多层屏蔽板和5至10厘米处的1毫米铝板屏蔽板，抵御高速尘埃撞击。大约一半的VEGA航天器用于哈雷模块，另一半用于金星着陆器组件。总科学有效载荷重量为144.3公斤。

金星组件包括一个直径240厘米的球体，在到达金星前两天分离，并以倾斜的轨迹进入行星大气层，没有进行主动机动，这与之前的维纳任务类似。着陆器探测器与维纳9号至14号相同，同样具有两个目标：研究大气层和研究地表地壳。除了温度和压力测量仪器外，下降探测器还携带了一个用于测量大气中次要成分的紫外光谱仪、一个用于测量H2O浓度的专用仪器以及其他用于确定凝结核化学组成的仪器：一个气相色谱仪、一个观察颗粒或液滴荧光的X射线光谱仪以及一个测量颗粒或液滴化学组成的质谱仪。X射线光谱仪使用激光成像装置根据颗粒大小进行分离，而质谱仪则使用空气动力学惯性分离器根据颗粒大小进行分离。着陆后，探测器附近的小表面样品将通过伽马光谱学和X射线荧光分析。紫外光谱仪、质谱仪和压力及温度测量仪器是在法国和苏联研究人员之间的合作下开发的。

除了着陆器探测器外，在进入大气层后，从上部热保护半球部署了一个恒压仪器化气球浮体。它在约50公里的高度漂浮在金星三层云系统中最活跃的中层。气球仪器的数据在任务47小时的寿命内直接传送到地球。