1. INTRODUCTION

This document describes the commanding required by C1XS in the post-launch, commissioning and lunar operation phases. Copies of the telecommand files are contained in the appendix.

As the C1XS commanding is dependant on events the telecommand files have been created assuming a start date of 1 Jan 2008, duration of 1 day and a start time of 00:00:00. The following sections describe the commanding in detail and also state which event they are expected to be run from. In addition all the command files assume that:

C1XS is powered on 30 seconds before the command file is sent
The CAN bus is enabled by the BDH.
The spacecraft SSR is collecting C1XS data.

2. ABBRIEVIATIONS

BDH Baseband Data Handling (unit)

CAN Controller Area Network (data bus)

C1XS Chandrayaan-1 X-ray Spectrometer

EEPROM Electrically Erasable Programmable Read Only Memory

SSR Solid State Recorder

TC Telecommand

TLM Telemetry

XSM X-ray Solar Monitor

3. POST LAUNCH

3.1 Rationale

During launch there is a possibility that the XSM shutter may open. The shutter protects the detector from protons during the spacecraft transit from the Earth to the Moon and so it is essential that the C1XS instrument be powered on briefly to allow the XSM shutter to be closed.

3.2 Timing

As soon as practical after launch the C1XS instrument should be switched on and the command file sent to the instrument.

3.3 Command File

Filename: c1xs_XSMshuter_v1.txt

Version: 1

Duration: 60 seconds

Depends: Instrument power on and CAN communications for >30 seconds

Completed State: Instrument in standby, power off after 30 seconds

Description: The instrument housekeeping rate is increased to one packet every 4 seconds, the XSM instrument is powered on, the shutter close command sent and then the XSM power is switched off.

4. COMMISSIONING

4.1 Rationale

Before science operations can take place the C1XS door catch has to be released.

4.2 Timing

This command file should be run during the C1XS instrument commissioning phase.

4.3 Command File

Filename: c1xs_openHOP_v1.txt

Version: 1

Duration: 12.5 minutes

Depends: Instrument power on and CAN communications for >30 seconds.

The instrument temperature should be <20 °C and the SCD radiator should be < -30°C.

Completed State: Instrument in standby, power off after 30 seconds

Description: The instrument housekeeping rate is increased to one packet every 4 seconds, the door latch time-out is increased to 3 minutes and the latch drive circuit is enabled. The open latch command is sent and the script waits for 5 minutes to ensure that the latch has opened and cooled down. The door is then opened and closed to check that the latch has correctly withdrawn. To verify that the rest of the instrument is working correctly it is put into operating mode for 5 minutes to collect data from the calibration sources.

5. LUNAR OPERATIONS

5.1 Rationale

Under normal operations the C1XS instrument requires very little commanding, 5 command files in total; on, operating, standby, calibrate and off.

The instrument should be left powered on, in standby mode, while the spacecraft is flying over the dark side of the Moon.

Once per day the instrument door needs to be closed so that the calibration sources can be used to monitor the degradation of the X-ray detectors.

5.2 Timing

The C1XS instrument only collects data while flying over the sunlit side of the Moon. Therefore the operating and standby command need to occur just before / just after the terminator is crossed. To maximise the collection of scientific data the on, off and calibration files should be run whilst the spacecraft is over the dark side.

5.3 Command Files

5.3.1 On

Filename: c1xs_on_v1.txt

Version: 1

Duration: 21.5 minutes

Depends: Instrument power on and CAN communications for >30 seconds

Completed State: Instrument in standby mode, C1XS door open.

Description: After power on the instrument runs the software located in PROM, an update was made to the on-board software during final test and this is located in EEPROM. Therefore the first two commands cause the software to reboot and run the latest version held in EEPROM. Ten minutes of calibration data is taken by commanding operating mode, after this time standby mode is requested and the C1XS door is opened.

5.3.2 Operating

Filename: c1xs_operating_v1.txt

Version: 1

Duration: 10 seconds

Event: 300 seconds before dark to sun-lit terminator crossing.

Depends: Instrument in standby mode, C1XS door open

Completed State: Instrument in operating mode

Description: The instrument is commanded into operating mode.

5.3.3 Standby

Filename: c1xs_standby_v1.txt

Version: 1

Duration: 10 seconds

Event: Terminator crossing, sun-lit to dark

Depends: Instrument in operating mode

Completed State: Instrument in standby mode.

Description: The instrument is commanded into standby mode.

5.3.4 Off

Filename: c1xs_off_v1.txt.txt

Version: 1

Duration: 20.5 minutes

Depends: Instrument in standby

Completed State: Instrument in standby, C1XS door closed, power off after 30 seconds

Description: The C1XS door is closed, operating mode is commanded to collect 10 minutes of calibration data, then the instrument is returned to standby mode ready for power off.

5.3.5 Calibration

Filename: c1xs_calibrate_v1.txt

Version: 1

Duration: 11.5 minutes

Event: Once per day, spacecraft over Moon's dark side.

Depends: Instrument in standby, C1XS door open.

Completed State: Instrument in standby, C1XS door open.

Description: The script closes the C1XS door, commands operating mode and 10 minutes later goes back to standby mode. The door is then re-opened ready for the next science observation.

1. ABNORMAL OPERATIONS

In the case of any problems with the C1XS instrument or command files please contact:

Shyama Narendranath.K.C : Tel: +91 80 2508 3708

email: kcshyama@isac.gov.in

Chris Howe: Tel: +44 (0)1235 445016

email: chris.howe@stfc.ac.uk

APPENDIX - COMMAND FILES

c1xs_calibrate_v1.txt

0000 ISRO CH-1 CXS 01-Jan-2008 1 01-Jan-2008 01-Jan-2008 0000 0005

0001 01-Jan-2008 00:00:00 STANDBY 14 13EEC0000007070000000000C562

0002 01-Jan-2008 00:00:30 DCIXS_DOOR 3 400 20 14 13EEC00100071103019000140BCE

0003 01-Jan-2008 00:01:00 OPERATING 14 13EEC002000706000000000046A5

0004 01-Jan-2008 00:11:00 STANDBY 14 13EEC0030007070000000000E826

0005 01-Jan-2008 00:11:30 DCIXS_DOOR 7 400 20 14 13EEC0040007110701900014F504

c1xs_off_v1.txt

0000  ISRO  CH-1  CXS  01-Jan-2008  1  01-Jan-2008   01-Jan-2008  0000  0004

0001  01-Jan-2008  00:00:00  STANDBY                                    14  13EEC0000007070000000000C562    
0002  01-Jan-2008  00:10:00  DCIXS_DOOR 3 400 20                        14  13EEC00100071103019000140BCE    
0003  01-Jan-2008  00:10:30  OPERATING                                  14  13EEC002000706000000000046A5    
0004  01-Jan-2008  00:20:30  STANDBY                                    14  13EEC0030007070000000000E826

c1xs_on_v1.txt

0000  ISRO  CH-1  CXS  01-Jan-2008  1  01-Jan-2008   01-Jan-2008  0000  0005

0001  01-Jan-2008  00:00:00  EMODE                                      14  13EEC00000070500000000004E22    
0002  01-Jan-2008  00:00:30  BOOT 5 0X8000                              14  13EEC00100072B0580000000EEC5    
0003  01-Jan-2008  00:01:30  OPERATING                                  14  13EEC002000706000000000046A5    
0004  01-Jan-2008  00:11:30  STANDBY                                    14  13EEC0030007070000000000E826    
0005  01-Jan-2008  00:21:30  DCIXS_DOOR 7 400 20                        14  13EEC0040007110701900014F504

c1xs_openHOP_v1.txt

0000 ISRO CH-1 CXS 01-Jan-2008 1 01-Jan-2008 01-Jan-2008 0000 0008

0001 01-Jan-2008 00:00:00 HKRATE 1 16 13EEC00000090E06000000010001090F

0002 01-Jan-2008 00:00:10 RAM_TABLE 6 1 180 16 13EEC00100090E060001000100B48C69

0003 01-Jan-2008 00:00:20 ENBL_LATCH 0XD6 14 13EEC002000714D6000000002D06

0004 01-Jan-2008 00:00:30 OPEN_LATCH 14 13EEC0030007130000000000F403

0005 01-Jan-2008 00:05:30 DCIXS_DOOR 7 400 20 14 13EEC0040007110701900014F504

0006 01-Jan-2008 00:06:30 DCIXS_DOOR 3 400 20 14 13EEC00500071103019000149721

0007 01-Jan-2008 00:07:30 OPERATING 14 13EEC0060007060000000000DA4A

0008 01-Jan-2008 00:12:30 STANDBY 14 13EEC007000707000000000074C9

c1xs_operating_v1.txt

0000  ISRO  CH-1  CXS  01-Jan-2008  1  01-Jan-2008   01-Jan-2008  0000  0001

0001  01-Jan-2008  00:00:00  OPERATING                                  14  13EEC000000706000000000080C2

c1xs_standby_v1.txt

0000  ISRO  CH-1  CXS  01-Jan-2008  1  01-Jan-2008   01-Jan-2008  0000  0001

0001  01-Jan-2008  00:00:00  STANDBY                                    14  13EEC0000007070000000000C562

c1xs_XSMshuter_v1.txt

0000  ISRO  CH-1  CXS  01-Jan-2008  1  01-Jan-2008   01-Jan-2008  0000  0004

0001  01-Jan-2008  00:00:00  HKRATE 1                                   16  13EEC00000090E06000000010001090F    
0002  01-Jan-2008  00:00:10  XSM_12V 1                                  14  13EEC00100071B01000000009577    
0003  01-Jan-2008  00:00:20  XSM_SHUTR 0                                14  13EEC00200071200000000005A80    
0004  01-Jan-2008  00:00:50  XSM_12V 0                                  14  13EEC00300071B0000000000F941

Date	Iss/Rev	Section	Comments
04-09-2008	1	all	Initial issue