EIR-OPS-004: Initial AOS


Objective

To establish and confirm 2-way communication with EIRSAT-1 for the first time on-orbit.


Introduction

Using this procedure, the Operator will prepare for and make first contact with the spacecraft following launch. At this point in the mission, the flight software is expected to be executing the Separation Sequence. The mission image running on the OBC could be the failsafe or primary1 image. The Operator will communicate with the spacecraft to assess its state and to verify that the antennas are fully deployed prior to making the decision to finish the Separation Sequence. Note that if the failsafe image is the current boot image, this procedure will re-direct the Operator to an alternative procedure to achieve these aims.


Procedure

This procedure contains the following sub-procedures:

A. Pre-Pass Preparation
B. Initial Get TCs
C. Data Downlink
D. Data Analysis (After the Communication Pass)

Important

Section A should be completed well in advance (hours!) of the first attempted communication pass with EIRSAT-1 to ensure the Operators are prepared for 2-way communication with the satellite. Communication with the spacecraft is required for Sections B and C of this procedure.

Important

This procedure will likely require more than one communication pass. TM/TC should be the Operators sole priority during the passes. Analysis (i.e. Section D) should be performed in parallel by other members of the team or outside of the communication windows.


A. Pre-Pass Preparation

A.1.


A.2.

  • To use the pass time efficiently, prepare the parameters and actions (i.e. open them in MCS) that will be used during the pass, as demonstrated in Figure 1.

../../../_images/PrePassPrep1.png

Figure 1 - Actions and parameters opened in MCS prior to the Start Communication Pass Procedure.


A.3.

  • Taking the time since on-orbit deployment (i.e. the time since power ON) and given the known frequency at which the different data packets are logged on-board, approximate the number of rows of data that will be available for downlink in the ADM, HK, TED, PASCAL, etc. storage channels by the first communication pass with EIRSAT-1.

  • Use ROW to assist with this.


A.4.

  • In Section C of this procedure, EIRSAT-1’s first Large Data Transfer (LDT) of logged on-board data will be set up. In preparation for this, ensure that you:


A.5.

  • Determine the durations of the next communication passes with the satellite and when they will occur.


A.6.

  • Using the upcoming pass durations (determined in Step A.5) and the expected data available for downlink (determined in Step A.3), estimate the amount of data to downlink from the HK, Event and ADM (and/or other) storage channels during the first communication passes with EIRSAT-1.

  • Use ROW to assist with this.

  • Suggested downlink priorities can be found in Section C of this procedure and, for the case where failsafe is the current boot image at initial AOS, Section A of the EIR-OPS-005: Failsafe at Initial AOS procedure.



B. Initial Get TCs

Important

This section should only be attempted more than 45 minutes after on-orbit deployment (i.e. after antenna deployment) and when the spacecraft is expected in the FoV of EIRSAT-1’s GS.

B.1.

  • Get the Version.satelliteString parameter frequently (i.e. with ~10 seconds between each TC).

  • Begin sending these TCs ~30 seconds before the expected time of AOS.

  • Continue to send these TCs until:

    • TM is received from EIRSAT-1 (as per the TM/TC Details table),

    • The expected time of LOS has passed, or

    • An issue is expected with the communications chain. Refer to EIR-OPS-032: Separation Sequence Restarted for some guidance in this case and request support from senior team members!

TC Details

MCS Operation

Get

Action/Param Name

Version.satelliteString

Data Expected with TC

No

TM Details

Data Expected from TC

satelliteString ( + ACK )

Data Size

8 bytes

Data Info

the “EIRSAT-1” string.

Allowed Value(s)

E I R S A T - 1

Expected Value(s)

E I R S A T - 1

B.2.

  • If no TM or a NACK is returned from the spacecraft over the pass duration, do not proceed with the remainder of this procedure. Instead, proceed to NACK/Timeout/Unexpected TM and discuss the situation with the senior team.

  • Else, if the satelliteString parameter is returned (as shown in Figure 2), continue with the remainder of this procedure.


    ../../../_images/eirsattring.png

    Figure 2 - TM from the satelliteString parameter in string format.


    ../../../_images/success.jpg

B.3.

  • Get the platform.OBC.obc.currBootImage parameter to determine the OBC’s current boot image.

  • Take note of this value for use in later steps.

TC Details

MCS Operation

Get

Action/Param Name

platform.OBC.obc.currBootImage

Data Expected with TC

No

TM Details

Data Expected from TC

currBootImage ( + ACK )

Data Size

1 byte

Data Info

the current boot image of EIRSAT-1

Allowed Value(s)

00, 01 and 02 (Hex)

Expected Value

00 or 01 (Hex)

Where…

currBootImage

Image

0

failsafe

1

primary1

Note

The spacecraft’s first boot image should be the primary1 image. If the spacecraft reboots (or the OBC resets) <2 hours after booting, the primary1 image will be marked as unstable and the failsafe image will be entered.


B.4.

  • Based on the currBootImage :

    • Ensure the appropriate SCDB is loaded into MCS, and

    • Determine what step to proceed to next using the below table.

currBootImage

Next step

0

Skip to Step B.7. As there is no ModeManager in failsafe and so ModeManager-related steps should be skipped.

1

Proceed to Step B.5.

B.5.

  • Invoke the mission.ModeManager.startPass action to start a communication pass.

Note

Enabling a communication pass will enable automatic and periodic transmission of live HK data from the spacecraft in place of the TM beacon data, which is transmitted outside of the pass. Automatic transmission of any on-board events raised during the pass will also be enabled throughout the pass. This on-board behavior will automatically time-out ~3 minutes after the last TC is received by the spacecraft.

TC Details

MCS Operation

Invoke

Action/Param Name

mission.ModeManager.startPass

Data Expected with TC

No

TM Details

Data Expected from TC

No ( + ACK )

B.6.

  • Get the mission.ModeManager.Mode parameter.

  • Confirm that the Separation Sequence Mode (i.e. 0) is returned.

TC Details

MCS Operation

Get

Action/Param Name

mission.ModeManager.Mode

Data Expected with TC

No

TM Details

Data Expected from TC

Mode ( + ACK )

Data Size

1 byte

Data Info

the current Operational Mode of EIRSAT-1

Allowed Value(s)

00- 04 (Hex)

Expected Value(s)

00 (Hex)

Where…

Mode

Operational Mode

00

Separation Sequence

01

Commissioning

02

Nominal

03

WBC

04

Safe

Tip

The next steps of this procedure primarily instruct the Operators to Get parameters, with no instruction on what to do about the returned TM. This is because this information will be used in later steps of this procedure and/or to assist the data analyses of other procedures.


B.7.

  • To determine which state the Separation Sequence is in and to confirm that resistor burn attempts are still on-going, Get the mission.SeparationSequence.state parameter.

  • Ensure that the returned state is between 02 - 09.

TC Details

MCS Operation

Get

Action/Param Name

mission.SeparationSequence.state

Data Expected with TC

No

TM Details

Data Expected from TC

state + (ACK)

Data Size

1 byte; 11 bytes

Data Info

the current state of the Separation Sequence

Allowed Value(s)

00 - 09 or 42 (Hex)

Expected Value(s)

02 - 09 (Hex)

where…

state

State

00

Init

01

PostLaunchWait

02

MinYPrimaryBurnStart

03

PlusYPrimaryBurnStart

04

MinXPrimaryBurnStart

05

PlusXPrimaryBurnStart

06

BurnTimeWait

07

BurnOff

08

BetweenBurnWait

09

SecondaryBurnStart

42

Finish

B.8.

  • Get the platform.ADM.SwitchesStatuses parameter to very preliminarily confirm the current state of the ADM switches.

Note

The state of the ADM switches determined in this step will be confirmed later with downlinked data.

TC Details

MCS Operation

Get

Action/Param Name

platform.ADM.SwitchesStatuses

Data Expected with TC

No

TM Details

Data Expected from TC

SwitchesStatuses ( + ACK )

Data Size

1 byte

Data Info

a 4-bit bitmap of the ADM switch states + 1 error bit

Allowed Value(s)

00000 - 11111 (binary)

Expected Value

01111 (No error, all ADM switches open)

Where…

SwitchesStatuses

ADM Switch States

0

Closed

1

Open

and…

Bits

Antenna element

Bit 0/LSB

+X

Bit 1

+Y

Bit 2

-X

Bit 3

-Y

Bit 4/MSP

N/A (error bit, where 1 = error)

B.9.

  • Get the core.OBT.uptime parameter to determine the elapsed time since the last reboot.

TC Details

MCS Operation

Get

Action/Param Name

core.OBT.uptime

Data Expected with TC

No

TM Details

Data Expected from TC

uptime ( + ACK )

Data Size

4 bytes

Data Info

Uptime (i.e. elapsed time since the last reboot)

Allowed Value(s)

00000000 - FFFFFFFF (hex)

Expected Value(s)

> 0

B.10.

  • Get the core.OBT.time parameter 10 times, with ~5 seconds between each TC, to determine what on-board time corresponds to in real time.

Note

This data will be used by the GS team after the pass. The Operator does not need to perform any assessment of the returned TM during the pass.

TC Details

MCS Operation

Get

Action/Param Name

core.OBT.time

Data Expected with TC

No

TM Details

Data Expected from TC

time + (ACK)

Data Size

4 bytes

Data Info

EIRSAT-1’s on-board time

Allowed Value(s)

00000000-FFFFFFFF

Expected Value(s)

>0

B.11.

  • Get the platform.EPS.busVoltages parameter with First row = Last row = 0 to determine the on-board voltage levels.

Danger

If busVoltages[0] <780 (dec), which corresponds to ~7.0V, the Operators are advised to postpone initiating any procedures in this pass in which the spacecraft consumes more power. This includes procedures that lead to increased RF transmissions, powering ON/enabling experiments and operating the ADCS. In the case where data downlinking is required for failure analyses, a limited amount of data downlinking is permitted.

TC Details

MCS Operation

Get

Action/Param Name

platform.EPS.busVoltages

Data Expected with TC

First Row, Last Row

Data Size

2 bytes, 2 bytes

Data Info

The first and last rows/indexes of the parameter to get

Allowed Value(s)

0 - 3

Expected Value(s)

0, 0

TM Details

Data Expected from TC

busVoltages ( + ACK )

Data Size

Int10

Data Info

busVoltages[0] = BatteryV bus, [1] = 3.3V, [2] = 5V, [3] = 12V

Allowed Value(s)

0 - 1023 (dec)

B.12.

  • Get the platform.CMC.tempaturePa parameter to determine the CMC PA temperature.

Danger

If temperaturePa >50 degrees Celsius, the Operators are advised to postpone initiating any procedures in this pass in which a significant amount of RF transmissions are likely. In this case, the Operators should monitor temperaturePa and only initiate such procedures when the parameter value falls below 45 degrees Celsius.

TC Details

MCS Operation

Get

Action/Param Name

platform.CMC.tempaturePa

Data Expected with TC

No

TM Details

Data Expected from TC

tempaturePa ( + ACK )

Data Size

signed Int8

Data Info

Temperature of the CMC power amplifier in degrees C

Allowed Value(s)

-128 - 128 (dec)

B.13.

  • The Operators should now proceed with LDTs, following the EIR-OPS-011: Downlink Data From Storage procedure. However, this should be done with care for the current state of the spacecraft (i.e. as the ‘Danger’ boxes advise in the previous two steps).

Important

LDTs should only be requested one at a time! When a transfer is complete, another can be started using the EIR-OPS-011: Downlink Data From Storage procedure. Get / Set TCs of other procedures may be carried out in parallel to LDTs, however, it should be noted that in this case the TM response time will be slowed.

  • For guidance on what to downlink:

    Danger

    If in the failsafe image, live transmission of event data is not enabled as part of this procedure, and so the Operator should be careful to monitor the CMC PA temperature (i.e. platform.CMC.temperaturePa) when downlinking data during the pass.



D. Data Analysis (After the Communication Pass)

Note

The analysis to be carried out by the team is very dependent on the findings as well as what data was successfully downlinked in Section C. Therefore, rather than a strict set of instructions, this section instead provides information to help guide the Operator in their analyses. Also note that in addition to any data downlinked by the UCD GS, data obtained via the amateur radio community may also be used to support the analysis/findings.

SPACECRAFT HEALTH CHECK

D.1.

  • Any HK data downlinked should now be checked to assess the current state of the spacecraft and its subsystems.

  • Do any of the HK parameters cause reason for concern? e.g:

    • Is the most recent value of the Uptime parameter consistent with the expected Mission Elapsed Time (MET) since launch?

    • Are the battery bus voltage levels nominal?

    • Are the various EPS and/or battery reset counters as expected given their pre-launch values?

    • Has the temperature of the CMC Power Amplifier stayed within expected/acceptable limits since RF transmissions were enabled?

Tip

In addition to the most recent value of each parameter, check how the values changed with time. Use the Grafana to help with this.


2-WAY COMMUNICATION CONFIRMATION

D.2.

  • The downlinked data should now be assessed to confirm with confidence, that:

    1. full antenna deployment has occurred, and

    2. nominal 2-way communication have been achieved.

  • To do this, the following should be considered:

    • Does the downlinked Event data suggest that the Separation Sequence successfully progressed to and through the different burn and between-burn-wait states (i.e. are Separation Sequence ‘StateFunctionComplete’ events observed with Event Data = the IDs of the burn and between-burn-wait states)?

      Tip

      To aid this assessment, the Operators can review Event log data downlinked during the MMTs here for comparison with their data.

    • In the downlinked ADM data:

      • Do the ADM switch states, read by both the OBC and the EMOD MSP (i.e. mission.SeparationSequence.AntSwitchesStatuses and platform.ADM.SwitchesStatuses ), indicate that the antenna elements have been deployed?

      • Do the deployment times of the different elements coincide with the resistor burns?

      • Do the PDM currents show that the correct current went through the resistors for the correct amount of time during the resistor burns?

    • In the downlinked HK data:

      • Check that the temperature of the CMC Power Amplifier increased only after RF transmissions were enabled to confirm that RF transmissions enabled when expected.


D.4.

  • While antenna deployment is not confirmed, continue to downlink data (i.e. as in Section C) during subsequent passes until the data indicates with confidence that all antennas have deployed.

  • However, once the successful deployment of the antennas is confirmed, the Operators can begin the EIR-OPS-006: Commissioning Procedure.


END OF PROCEDURE