Nutation Testing - Ulysses

ULYSSES TEST PLAN FOR NUTATION OPERATIONS 2000-2001

1. INTRODUCTION

Due to the long interval since the last nutation period and the upcoming nutation period the objectives of this test plan are as follows:

• To test station and communications equipment installation and operation
• To revalidate spacecraft and ground segment procedures for conscan operations
• To retrain and refamiliarize DSN, ESA and University of Santiago operations staff with the ways of operating the spacecraft and ground segment
• To revalidate the Kourou commanding software and communications links

The following functions will be tested to ensure safe conscan support capability:

• Uplink Stability. The antenna has to demonstrate a stable uplink of sufficient power (spacecraft received AGC levels significantly greater than the threshold of -147 dBm)
• Command Modulation. Correct command suppression of the carrier signal (-3.46 dB)
• Command Test. Successful transmission and reception of commands to Ulysses (except for Santiago)
• Uplink Transfers. The antenna under test has to demonstrate coordinated uplink transfers to and from a DSN station, as this would be a regular operation (except for Santiago, as it would be used for emergencies only)
• Telemetry. The antenna has to be capable of receiving spacecraft telemetry for monitoring the manoeuvre. Santiago will be tested for carrier signal visibility, as a contingency requirement.
• Spacecraft conscan. If all of the above tests are successful, then the spacecraft will perform a conscan manoeuvre using that antenna's uplink signal.
• New Transmitter Limits. An uplink needs to be scheduled at the beginning and at the end of view to test the 6.2° limit for each antenna and at all complexes.

2. SANTIAGO

The following tests have been performed with the Santiago Station (DSS 74).

• Uplink to Ulysses at 10 kW, 5 kW and 2.5 kW to assess stability.
• Attempts to view the carrier-only signal from the spacecraft.

All tests were in parallel with a DSS track.

TESTING SANTIAGO UPLINK TO ULYSSES WITH DSN DOWNLINK

Table 1: Santiago Tests

Detailed test plans were produced for each test.

3. KOUROU

3.1 Data Flow Tests

Once the links between JPL, ESOC and Kourou had been established, Data Flow Tests (DFTs) were performed. A PSS at Kourou was used to generate telemetry formats compatible with the Ulysses spacecraft. Specifically the following tests were be performed:

• Receive and process telemetry at JPL (on ULYBK) generated by the PSS at 1024 bps, 512 bps, 256 bps & 128 bps SCI, and 1024 bps & 64 bps ENG.
• Transmit commands from JPL (from ULYBK) to Kourou and check correct reception at Kourou by analysis of hex dumps.
• Exercise the voice loops.

These tests were performed during the period from 28 August to 25 September 2000.

Detailed test plans were produced for each test.

3.1 Mission Readiness Tests

The following tests are being performed with the Kourou Station (DSS75) during Mission Readiness Tests (MRTs)

• Uplink to Ulysses at 2 kW, 1 kW and 0.4 kW to assess stability.
• Command Modulation. Correct command suppression of the carrier signal (-3.46 dB)
• Command Test. Successful transmission and reception of commands to Ulysses
• Uplink Transfers. Transfers to and from DSN stations.
• Telemetry Bit rates of 512 (may not be possible), 256 and 128 bps
• Any test can be repeated in case of failure or for station personnel training. All tests will be in parallel with a DSS track.

Detailed test plans will be produced for each test.

TESTING KOUROU UPLINK TO ULYSSES WITH DSN DOWNLINK

Table 2: Kourou MRT Dates. Overlap times with the DSN stations are given. The start time of the overlap corresponds with the BOT of the DSN station. Kourou needs approximately 30 minutes to reconfigure after its XMM support.

4. DSN

The following testing will be performed using the DSN antennas at Canberra:

• New Transmitter Limits. An uplink needs to be scheduled at the beginning and at the end of view to test the 6.2° limit for each antenna and at all complexes.
• 26m antenna test to verify uplink/command capability

Possible dates for testing have been planned for early November 2000 (see section 5 for details).  Note that the low elevation tranmitter modifications have not yet been installed at DSS43, or at the Goldstone and Madrid complexes. The Madrid and Goldstone complexes lost view of Ulysses in mid-September and early-October respectively. They will be ready for low elevation transmitter operations in early 2001.

5. NUTATION OPERATIONS READINESS TESTING

During November 2000, spacecraft operations will gradually shift from routine to nutation support. In this period, tests of the on-board conscan function will be performed using Canberra, Kourou and Santiago stations.

In preparation for this the Ulysses Ground Operations Team (GOT) has scheduled additional tracking time.  Details can be found at http://ulysses-ops/ulsfct/tracking.html.

This additional time will be used by to prepare the Ulysses FCT, GOT, DSN, ESA and University of Santiago personnel for the upcoming period of continuous Nutation operations, which begin on 1 December 2000.

It will also be a shakedown period for all elements of the Nutation operations system, namely the spacecraft, the ground segment and all associated software, hardware and personnel required to support these activities.

Since early 2000 many of the sub-systems involved have been changed or modified to cope with the different demands of extended 24 hour Nutation operations.  Many of these changes require manual intervention and adjustment to make them work.  The period of readiness testing will test that these changes work, and that they are robust enough for the yearlong period of Nutation operations.

Readiness Test Objectives

The following are the main objectives of the Nutation operations readiness testing tracks in November 2000.

• To familiarize all FCT, GOT and DSN personnel with Nutation operations.
• To test the complete Nutation operations system in a realistic manner.

Detailed test objectives are as follows:

1. To demonstrate safe and predictable operation ofthe DSS34 antenna transmitter at low elevations (below 10.5°.
2. To demonstrate successful support of s/c closed-loop Conscan (CLC) operations using DSN, Kourou and Santiago antennas.
3. To validate all s/c and g/s Nutation operations procedures.
4. To demonstrate that s/c and g/s operations can be performed for a period of greater than 24 hours.
5. To verify the success of modifications to various DSN support products such as viewperiod generation files, antenna pointing predicts, SOE/SFOS generation, DSN keyword files.
6. To demonstrate correct identification and avoidance of cable wrap events, as predicted by the viewperiod files.

TESTING CONSCAN OPERATIONS

Table 3: Nutation Operations Readiness Test Dates.

6. NUTATION PREPARATION TEST MATRIX

Table 4: Test Matrix