Mission Overview

Phase: Launch
Time:
T to T+10 minutes
Goal:
Obtain reasonable orbit parameters and survive launch process
Description:
In this stage, the spacecraft power is off due to the separation switches being depressed (open). The batteries are at an unknown charge level and all antennas have not yet been deployed. The Battery System Manager and Charger (Charger/Manager) is in sleep mode, waiting for input from the solar panels.
 

Phase: Spacecraft Separation
Time:
T+15 minutes
Goal:
Successfully separate and wait for batteries to charge
Description:
In this stage, the two separation switches will close, allowing power from the solar panels to flow. For redundancy, only one of the two switches needs to close for power to flow. Once the Charger/Manager detects current from any of the solar panels it will exit sleep mode and begin charging the batteries. Once the minimum charge level is attained, the next phase of operation can begin.
 

Phase: Power-up Sequence
Time:
T+15 + battery charge time
Goal:
Power on Command and Data Handling (CDH) system
Description:
Once the Charger/Manager verifies the batteries have reached an appropriate charge, it will allow power to flow to the buck converters, therefore powering on CDH. The CDH system will initiate the system timer and begin recording system status information.
 

Phase: Antenna Deployment
Time:
T_power-up + 15
Goal:
Antennas deploy properly
Description:
15 minutes after CDH powers-on and begins tracking system time, it will check the battery levels to see if they are sufficiently charged for antenna deployment. If the batteries are not, the system will wait another 15 minutes and then check again until sufficient charge is attained. CDH will then send the command to the power system to deploy both the Primary Communications (PCOM) and High Speed Communications (HSCOM) antennas. upon receiving the command, the power system will send 1A of current through a length of Nickel-Chromium (nichrome) wire which is wrapped around the nylon fishing line holding the antennas. The nichrome wire will heat up and melt through the fishing line allowing the spring loaded antennas to deploy into operating position.
 

Phase: First Stage Check
Time:
T_power-up + 30
Goal:
Enter beacon mode
Description:
Once the satellite is powered on and the antennas are deployed, it will enter beacon mode. The PCOM system will send short packets of information containing the satellite call sign and basic health information at a specified interval. Using telemetry information provided by the North American Aerospace Defense Command (NORAD), we will attempt to receive this beacon when the satellite is within line-of-sight (LOS) of our Boulder, Colorado, ground station. If we can not get telemetry information from NORAD, we will rely on the assistance of ham radio enthusiasts around the world to help locate our satellite. We will track the satellite in beacon mode until the Keplerian elements of the orbit can be determined. These will be input into Satellite Tool Kit (STK) which will model the orbit and inform us of pass times, duration, elevation angle, etc.

If the satellite is not contacted after a specified period of time, the CDH system will automatically switch the beacon mode from PCOM to HSCOM. This will be critical in the event of a PCOM antenna deployment malfunction.
 

Phase: Acquisition
Time:
unknown
Goal:
Achieve communications
Description:
Once the satellite is detected from its beacon mode, a command will be sent to the satellite for it to exit beacon mode. The satellite should respond with a downlink of health and status data.
 

Phase: PCOM/System Checkout
Time:
unknown
Goal:
Establish consistent communication via PCOM system, analyze health and status of satellite
Description:
In this stage, the satellite will downlink various data sets containing power and CDH information. This data will be analyzed to determine satellite health and ensure all systems are operation properly. ADCS will do preliminary attitude analysis from the current sensor data of the solar panels. If the PCOM system fails to communicate properly, the system checkout will occur with the HSCOM system in the next stage of operation.
 

Phase: HSCOM Checkout
Time:
T_PCOM-check + 1 week
Goal:
Verify functionality of HSCOM
Description:
In this stage, we will send a command via the PCOM system to enable HSCOM operations. Once basic operations is verified, the primary science mission of the satellite can begin and will continue throughout the remainder of Hermes operations. As data is collected by the satellite, we will test the data limits of the system and attempt to determine the maximum baud rate possible.


Phase: Environmental Analysis
Time:
unknown
Goal:
Return environmental data via HSCOM
Description:
This operation stage will also continue until the end of the satellite mission. At a specified time interval, the CDH system will poll the various temperature sensors, current sensors, and the magnetometer and store the data. During communication passes over Boulder, this data will be down-linked using the HSCOM system as specified above. The data will be analyzed on the ground to determine spacecraft attitude, component degradation, etc.


Phase: End of Defined Mission
Time:
T+1 year
Goal:
Achievement of required mission lifetime
Description:
After one year of on-orbit testing and communications, the Hermes mission officially ends. Operations will most likely continue for as long as possible after this stage. Since the satellite is capable of uploading programming code from the ground, it may possible to add further functionality to the satellite once it is in orbit. One exciting possibility in this stage is to become a relay station for CubeSat communications. As CubeSats get more advanced and more numerous with time, this could be a useful and beneficial goal for the waning years of Hermes life.


Phase: End of Life (EOL)
Time:
T + 2 years or more
Goal:
Spacecraft ceases to function
Description:
Due to radiation, the satellite will eventually cease to function as memory and microprocessors malfunction. At an initial orbit of 700km, it will take approximately 30 years for the satellite to descend into the atmosphere and burn up.

 

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