SC_SIM
The Spacecraft Simulator

I hear, I forget
I see, I remember
I do, I UNDERSTAND!


START THE SIMULATOR!!

Spacecraft basics Spacecraft Launch Orbit Commands Ending Simulation Acronyms Troubleshooting
I recommend you print this manual as you will need to reference it during the simulation.


Please note that as of 2/18/04 I am modifying this program for use as a simulator for groups of people to simulate launches as a team. Some features may or may not work depending on what I am working on. The Goal of this simulation is to launch your spacecraft and keep it in orbit for as long as you can, gathering as much SCIENCE DATA as you can before the spacecraft runs out of fuel, battery power, or becomes unusable in some other fashion. To keep things interesting the SCC (Space Craft Computer) is somewhat disabled so you must assume most of its functions. Also you will be in contact with the satellite for the entire orbit. In real life this is not the case.

I have attempted to keep the simulation as real as possible. EOS is not a "smaller/faster/better" satellite. It is a large complex science instrument and therefore running this simulator is not a simple thing to do. If you no nothing about satellites you will have many failures before you can keep EOS alive for any period of time. If you have questions e-mail us and we will help you out.

SPACECRAFT BASICS
The Simulator will now automatically start at "slow" or real time speed.
This is so you have time to fuel boosters, set up for launch etc. After about 14 minutes it will go go "MEDIUM" speed or 10 times real speed so an orbit will take about 10 minutes.
The EOS AM1 was launched on a 6 year mission on Dec 18, 1999. It has 5 instruments which are used to monitor the condition of the planet we all know and love called earth. Thus EOS stands for Earth Observation System. The spacecraft is basically composed of two parts. The BUS and the Instruments. The instruments are the payload. They are the reason we launched the satellite. They gather the SCIENCE DATA. The BUS is everything else needed to support the instruments. Electrical, Guidance, Navigation, Communication, Propulsion, Thermal etc. The BUS itself is a satellite but it has no reason to exist with out the instruments.

The EOS instruments:
CERES.....Cloud Earth Radiant Energy Sensor
ASTER.....Advanced Spaceborne Thermal Emissions and Reflection Radiometer
MOPITT....Measurement Of Pollution In The Troposphere
MODIS.....Moderate Resolution Imaging Spectroradiometer
MISER.....Multi-angle Imaging Spectroradiometer

I am not going into get the specifics of how each of them functions here. All that you need to know is that they gather the SCIENCE DATA. There are calibration functions that some of them require such as pointing them at the moon to calibrate them but I haven't programmed this in yet so don't worry about it...no wait a minute I did program them in ... yea...the SCC takes care of calibrating them....yea thats it I did program them in :) . One thing to remember is NEVER point them at the SUN, this WILL kill them.

Redundancy
The spacecraft has many backup systems. For example there is an ACE A and an ACE B. Both do not need to be on at the same time but one MUST be on for attitude control. If both ACE's die...shows over. You will note that most telemetry has an A and a B side. Most items only need one side on so try to keep everything on the A (or primary) side. Some items, such as the SCC (Space Craft Computer) require that the primary and backup be on all the time. This is due to the fact that the SCC has its memory loaded and it would have to be reloaded if you shut it off. If SCC1 died and you needed to turn on SCC2 you would have to reload its memory before you could use it. This takes up to much time and could end the mission so that is why the SCC's should always be on. Don’t forget to load the SCC FSW (Space Craft Computer Flight SoftWare) BEFORE you launch!!

Minimum systems

Due to the redundancy of systems there are you have to have a minimum of certain components alive to stay in orbit some of which are listed here.

Component.........Minimum needed
RWA.................3
ACE.................1
IRU.................2
SSST................1
SCC.................1
CTIU................1

LAUNCH
Before you start the countdown clock you have to configure for launch. On the pad the clock is sitting at t - 5 minutes. Simply send the commands to turn on/off the systems on the spacecraft that you want then send the command START_CLOCK to start the countdown clock and launch. In order to prepare for launch the spacecraft must be put into a condition in which there is a minimal risk for damage. To do this everything that can be shut off should be shut off. Part of the fun of this simulation is to figure out how to do this but here are some hints.

Launch Configuration:
1) The instruments are not used until you are in orbit so turn them off.
2) The batteries should have a full charge on them at liftoff.
3) Check each subsystem and turn off anything that is not used at launch. Some items must be on at launch such as RWA's, IRU's.
4)What should be on at launch:
RWAs, IRUs, ACE, SCCs, CTIUs.
What should be off at launch:
Everything else!
If for example you launch and have left an instrument on it could be damaged in ascent. Once you are on orbit it could be unusable. So be careful.

Orbit
Now that you have launched and are in orbit you have to get the spacecraft ready to do its job. The first thing you need to do is send the DEPLOY_ARRAY command to deploy the solar array so that the batteries don't die. Reconfigure any damaged/non functioning systems. Once this is done things are going to get a little busy. The satellite is in a 99 minute orbit 33 of which is in eclipse (not in the sun) so you will have to run on battery power. It is important to maintain the condition of the batteries so keep an eye on them. If they are not maintained it could shorten the life of the mission.

Normal Spacecraft operation:
Once on orbit and functioning the business of running Flight Ops is at hand. There are several goals to reach for on each orbit.

1) Gather as much data as possible (measured in kilobytes) by turning on the instruments.
2) Use as little fuel as you can.
3) Get as much of a charge on the batteries as you can.
4) Fix any anomalies that you can (things that break). Example: If the ACE A breaks turn on ACE B
5) Get setup for the next orbit.

As the simulation proceeds the condition of the batteries/Solar Array will deteriorate. At some point you will not have enough power to keep all the instruments on at the same time. When this happens you should turn off one or more instruments to lower the load and try to extend battery life.
The key is to keep on as much as you can while extending the life of the spacecraft as much as you can.
Ending the simulation
At the end of the simulation EOS AM1 will be dead. There are many reasons that this could happen. For example the batteries could be dead, The ACE A and B sides could break and you loose attitude control, two IRU's could break etc. When this happens the simulation will end and you will be graded on your performance. You could be kicked out of the training program or be promoted to the head of NASA. It all depends on how well you do.

Commands and their related telemetry points

When you send a command the status of a telemetry point should update. For example when you send the command TURN_ON_GNC_IRUA the telemetry point GNC_BR_IRUA_PWRRLY should read "ON". If it doesn't the IRU might be damaged. The commands are all structured like this:

ACTION_______SUBSYSTEM_______EQUIPMENT
TURN_ON_________GNC____________IRUA

Thus the command TURN_ON_GNC_IRUA will turn on the guidance and navigation IRUA.


Valid Commands:

These command turns on the ACE (Attitude Control Equipment). TURN_ON_GNC_ACE_A......telemetry point is GNC_BR_ACE_AONBOFF
TURN_ON_GNC_ACE_B......telemetry point is GNC_BR_ACE_AONBOFF

These commands turn on the MTRs. (Magnetic Torque Rods). These are basically large electromagnets that push against the earth’s magnetic field to turn the spacecraft. They are used for attitude control.
TURN_ON_GNC_MTR_XA......telemetry point is GNC_SD_ACE_MTR_XA
TURN_ON_GNC_MTR_XB......telemetry point is GNC_SD_ACE_MTR_XB
TURN_ON_GNC_MTR_YA......telemetry point is GNC_SD_ACE_MTR_YA
TURN_ON_GNC_MTR_YB......telemetry point is GNC_SD_ACE_MTR_YB
TURN_ON_GNC_MTR_ZA......telemetry point is GNC_SD_ACE_MTR_ZA
TURN_ON_GNC_MTR_ZB......telemetry point is GNC_SD_ACE_MTR_ZB
TURN_OFF_GNC_MTR_XA......telemetry point is GNC_SD_ACE_MTR_XA
TURN_OFF_GNC_MTR_XB......telemetry point is GNC_SD_ACE_MTR_XB
TURN_OFF_GNC_MTR_YA......telemetry point is GNC_SD_ACE_MTR_YA
TURN_OFF_GNC_MTR_YB......telemetry point is GNC_SD_ACE_MTR_YB
TURN_OFF_GNC_MTR_ZA......telemetry point is GNC_SD_ACE_MTR_ZA
TURN_OFF_GNC_MTR_ZB......telemetry point is GNC_SD_ACE_MTR_ZB

These commands turn on the SSSTs (Solid State Star Tracker). These are used to help the spacecraft know where it is in space. They look at the star field and derive the orientation based on the stars they see.
TURN_ON_GNC_SSST1......telemetry point is GNC_BR_SSST1_PWRRLY
TURN_ON_GNC_SSST2......telemetry point is GNC_BR_SSST2_PWRRLY
TURN_OFF_GNC_SSST1......telemetry point is GNC_BR_SSST1_PWRRLY
TURN_OFF_GNC_SSST2......telemetry point is GNC_BR_SSST2_PWRRLY

These commands effect the IRUs (Inertial Reference Units). These are gyroscopes that help the spacecraft know its orientation in space.
TURN_ON_GNC_IRUA......telemetry point is GNC_BR_IRUA_PWRRLY
TURN_ON_GNC_IRUB......telemetry point is GNC_BR_IRUB_PWRRLY
TURN_ON_GNC_IRUC......telemetry point is GNC_BR_IRUC_PWRRLY
TURN_OFF_GNC_IRUA......telemetry point is GNC_BR_IRUA_PWRRLY
TURN_OFF_GNC_IRUB......telemetry point is GNC_BR_IRUB_PWRRLY
TURN_OFF_GNC_IRUC......telemetry point is GNC_BR_IRUC_PWRRLY

These commands effect the RWAs (Reaction Wheel Assembly). These are large wheels that spin and keep the spacecraft stable. That also turn the spacecraft to keep it properly oriented.
TURN_ON_GNC_RWA1......telemetry point is GNC_SD_ACE_RWA1
TURN_ON_GNC_RWA2......telemetry point is GNC_SD_ACE_RWA2
TURN_ON_GNC_RWA3......telemetry point is GNC_SD_ACE_RWA3
TURN_ON_GNC_RWA4......telemetry point is GNC_SD_ACE_RWA4
TURN_OFF_GNC_RWA1......telemetry point is GNC_SD_ACE_RWA1
TURN_OFF_GNC_RWA2......telemetry point is GNC_SD_ACE_RWA2
TURN_OFF_GNC_RWA3......telemetry point is GNC_SD_ACE_RWA3
TURN_OFF_GNC_RWA4......telemetry point is GNC_SD_ACE_RWA4

These commands turn on/off load and activate the Space Craft Computers.
TURN_ON_CDH_SCC1......telemetry point is CDH_SD_SCC1
TURN_ON_CDH_SCC2......telemetry point is CDH_SD_SCC2
LOAD_CDH_SCC1_FSW......telemetry point is CDH_SD_SCC1_FSW
LOAD_CDH_SCC2_FSW......telemetry point is CDH_SD_SCC2_FSW
TURN_ON_CDH_SCC1_FSW......telemetry point is CDH_SD_SCC1_FSW
TURN_ON_CDH_SCC2_FSW......telemetry point is CDH_SD_SCC2_FSW

These commands deploy the High Gain Antenna and the solar array.
DEPLOY_COM_HGA......telemetry point is COM_SD_HGA_STAT
DEPLOY_ARRAY......telemetry point is S_ARRAY_STAT
TURN_ON_ARRAY_DRIVE.......telemetry point is EPS_ARRAY_DRIVE_STAT
The array drive keeps the solar panel pointed at the sun as the
satellite orbits. If you do not turn it on, or turn it on to early
(before array is deployed) you will damage drive and not charge the
batteries to full capasity.
TURN_OFF_ARRAY_DRIVE

These commands turn on the space craft instruments.
TURN_ON_EPS_ASTER......telemetry point is ASTER
TURN_OFF_EPS_ASTER......telemetry point is ASTER
TURN_ON_EPS_CERES......telemetry point is CERES
TURN_OFF_EPS_CERES......telemetry point is CERES
TURN_ON_EPS_MISER......telemetry point is MISER
TURN_OFF_EPS_MISER......telemetry point is MISER
TURN_ON_EPS_MODIS......telemetry point is MODIS
TURN_OFF_EPS_MODIS......telemetry point is MODIS
TURN_ON_EPS_MOPITT......telemetry point is MOPITT
TURN_OFF_EPS_MOPIT......telemetry point is MOPITT


OTHER COMMANDS
START_CLOCK - Starts the countdown clock.
FAST, MEDIUM, SLOW - Changes the simulation speed.
FUEL_STAGE_1.....Fuels booster
FUEL_STAGE_2
DISCONNECT_UMBILICAL_POWER......turns off external power
to rocket. If you launch and don't do this you may cause
a short and blow satellite fuses at launch, damaging it in some way.

EXAMPLE OF A MISSION
Start the simulator
Send the following commands
SLOW
START_CLOCK.......Starts timer
FUEL_STAGE_1
FUEL_STAGE_2
DISCONNECT_UMBILICAL_POWER
TURN_ON_GNC_RWA1
TURN_ON_GNC_RWA2
TURN_ON_GNC_RWA3
TURN_ON_GNC_IRUA
TURN_ON_GNC_IRUB
TURN_ON_GNC_SSST1
TURN_ON_CDH_SCC1
LOAD_CDH_SCC1_FSW
TURN_ON_CDH_SCC1_FSW
MEDIUM
DEPLOY_ARRAY..........Once in orbit
DEPLOY_COM_HGA........Once in orbit
TURN_ON_ASTER.........Once in orbit

This is a minimal setup for launch but it should give you an idea how to configure the spacecraft. Once in orbit you have to turn on instruments and gather as much data as you can while managing the spacecraft.


ACRONYMS

ACE - Attitude Control Equipment
ASTER - Advanced Spaceborne Thermal Emissions and Reflection Radiometer
BDU - Bus Data Unit
CDH - Commanding and Data Handling
CERES - Cloud Earth Radiant Energy Sensor
COM - Communications
CTIU - Command Telemetry Interface Unit
EPS - Electrical Power System
HGA - High Gain Antenna
GNC - Guidance Navigation and Control
IRU - Inertial Reference Unit
MISER - Multi-angle Imaging Spectroradiometer
MODIS - Moderate Resolution Imaging Spectroradiometer
MOPITT - Measurement Of Pollution In The Troposphere
MTR - Magnetic Toque Rod
PEM - Power Equipment Module
RWA - Reaction Wheel Assembly
SCC - Space Craft Computer
SSR - Solid State Recorder
SSST - Solid State Star Tracker
TCS - Thermal Control System

This Manual is presented to give you enough information to operate the spacecraft simulator, while leaving out just enough to make it interesting to figure out how to operate the spacecraft. I have attempted to give you enough information to run the spacecraft but if something is unclear let me know. The simulator is currently undergoing constant changes so if you see a bug I probably know about it check back soon to see if it is fixed or what changes I have made. I will be adding multiple telemetry pages soon so that the subsystems can each have there own telemetry pages. This is a work in progress so I encourage your opinion.
TROUBLESHOOTING
Using Microsoft Internet Explorer I get a "Class not found error"
Microsoft has done a wonderful job making JAVA semi compatible, therefore on some systems SC_SIM will throw this error. If you install SUN JAVA 1.4.2 (Link to be put here) that should solve the problem, make sure you use Internet Explorer 6 and that under tools/Internet options/advanced you select the SUN JAVA as the default. If you can get it to work install Netscape 7.1 that should work with the default install.