VEX-V-VRA-1-2-3-EXT3-0674

Data Set Overview The Venus Express (VEX) Radio Science (VeRa) Data Archive is a timeordered collection of raw and partially processed data collected during the Venus Express Mission. This is a Occultation measurement covering the time 20120824T23:43:17.050 to 20120825T01:17:48.949. This data set contains archival raw, partially processed, and ancillary/supporting radio science data acquired during the Routine Operations phase of the Venus Express (VEX) mission using ground facilities of the European Space Agency (ESA) and/or the NASA Deep Space Network (DSN). VeRa radio occultation observations start shortly before the occultation ingress, when the VEX spacecraft moves behind the planetary disk as seen from the Earth and stop shortly after the occultation egress, when the probe emerges from behind the planet. VeRa occultation data usually cover three recording phases: the occultation ingress (1), the time when the spacecraft is occulted by the planet (2) and the occultation egress (3). The different observation phases can be distinguished by regarding the AGC data, which records the strength of the received signal. In phase (1) and (3) the AGC level is high compared to phase (2). In Phase (2) still a signal may be received at the groundstation due to the strong bending of the radio waves in the dense atmosphere. The strength of the signal is significantly reduced and weakens further the deeper the radio waves penetrate the atmosphere until the groundstation may be unable to lock. Therefore, the beginning of phase (2) is recognized at first order by a sharp drop of the AGC down to 95 dB and lower and ends with a sharp rise in the AGC data back to the former AGC level. For the derivation of higher science products it is recommended to divide the level 2 data into an ingress and an egress part and to process these data seperatetly. This data set was collected during the VEX science subphase 46 (M truncated!, Please se [truncated!, Please see actual data for full text]

数据集概览

金星快车号（VEX）无线电科学（VeRa）数据档案是一个按时间顺序排列的原始及部分处理数据的集合，这些数据是在金星快车任务期间收集的。该数据集涵盖了20120824T23:43:17.050至20120825T01:17:48.949期间的光掩测量。本数据集包含存档的原始、部分处理及辅助/支持性的无线电科学数据，这些数据是在金星快车（VEX）任务的常规操作阶段，通过欧洲航天局（ESA）和/或美国宇航局深空网络（DSN）的地面设施获取的。VeRa光掩观测始于光掩入射前不久，此时金星快车航天器从地球视角移动至行星盘背后，并在探测器从行星背后出现的光掩出射后不久结束。VeRa光掩数据通常涵盖三个记录阶段：光掩入射阶段（1）、航天器被行星掩蔽的时间（2）以及光掩出射阶段（3）。不同的观测阶段可以通过考虑自动增益控制（AGC）数据来区分，该数据记录了接收信号的强度。在阶段（1）和（3）中，AGC水平相对于阶段（2）较高。在阶段（2）中，由于密集大气层中无线电波的强烈弯曲，地面站仍可能接收到信号。信号的强度显著降低，并且随着无线电波穿透大气层的深度增加而进一步减弱，直至地面站可能无法锁定。因此，阶段（2）的开始可以通过AGC数据中的急剧下降至95分贝以下来首次识别，并随着AGC数据中的急剧上升恢复至先前的AGC水平而结束。为了推导出更高层次的科学产品，建议将2级数据分为入射和出射部分，并分别对这些数据进行处理。本数据集是在VEX科学子阶段46（数据截断！请参阅[数据截断！请参阅实际数据以获取全文]）期间收集的。