MESSENGER RSS Antenna Configuration Record (ANT)

ANT – Antenna Configuration Record

Instrument: MESSENGER Radio Science Experiment

PDS Data Set ID: MESS-V/H-RSS-1-EDR-RAWDATA-V1.0

For more information about the RSS ANT product, see the ANT File Description.

The Radio Science Subsystem (RSS) Antenna Configuration Record (ANT) file contains the configuration of the MESSENGER spacecraft RF antennas during the period when MESSENGER was in orbit about Mercury. There are also configurations for each of the three flybys of Mercury and for a period of a few weeks before and after each Mercury flyby. The primary purpose of the ANT file is to supply information to the navigation and Radio Science teams for use in their trajectory-construction analyses. A new version of the ANT file is created with each PDS release. The ANT file is in accumulating time, with each row indicating a change in antenna configuration. In between the rows, antenna configuration is unchanged. Since a row is added only when the antenna configuration changes, the rows are not separated by equal increments in time.

The data in the ANT file is based on the command load sent to the spacecraft. In rare cases, the as-flown configuration may be different due to a real-time command that changed the antenna configuration or due to a spacecraft anomaly that triggered a spacecraft autonomous response that reconfigured the RF system. For example, when the spacecraft enters a safe mode, it may reconfigure the RF system to use the fan beam antenna. In some such cases, such as the third flyby, the ANT file is modified to reflect the as-flown configuration.

Each row has five entries or columns, separated by spaces. The first three entries describe the time that the change in antenna configuration occurred. The last two entries describe the antenna configuration. Note that each row contains two times. The first time is the ground-receive time (in UTC), and the second time is spacecraft time (in MET). These times differ by the one-way light time.

The RSS ANT file is named MESS_RS_ANT.TXT, with its corresponding label file.

In ODE, the ANT file has the following product ID:

MESS_RS_ANT