You can open a new Countdown File (*.cdo) by clicking on the folder in the lower right corner of the screen.
When the countdown is under 1 hour, a blinking yellow indicator light displays to the right of the Mission Clock.  When the count goes below 10 minutes, two blinking yellow indicator lights display.  At less than 1 minute remaining in the countdown a blinking green alternates with two blinking yellow indicator light.
The Mission Clock turns green at T - 0 / 00:00:00; up until then it displays red.
You can set a launch date by double clicking on the white Launch Date box.  This opens up a point-and-click calendar.
When you hold the countdown, a warning light will appear above the Mission Clock when less than 1 minute remains in the Launch Window.
You can enable and view the Tip of the Day from the Help Menu.
A Launch Window is the total length of time that you can be on hold during the countdown.  When the Launch Window expires (or reaches 00:00:00), the launch must be rescheduled.
You must enable HOLD for the Hold Button to work.  You can enable the HOLD in the Settings Menu.  This keeps you from activating the Hold button by mistake.
The Launch Date/Time must be entered into the computer before it works. Launch Dates/Times can be entered by clicking the Set Launch Time button.
You can quickly access the Event Timers window by Right-Clicking on the Mission Elapsed Time window, and then clicking on the "Show Event Timers . . . " menu.  You can also get to the Event Timers window through any "Settings" menu.
Clicking the Sequence Events button on the Event Timers window will put all of your Mission Events in chronological order.
The Launch Window time is not entered in the computer until you click on the Set Launch Window button.  You must then check the Active Launch Window button to make the Launch Window actually work during a Hold.
When changing Launch Times or Launch Windows you can click inside the white box to increase either seconds, minutes, or hours by one per click.
Clicking the displayed Launch Date will increase the Launch Date Setting in the white box by one day.  Clicking on the label below the white box (Launch Date MM/DD/YYYY) will decrease the date by one day.
You can use the Sim Time Menu to set the computer's clock so that any Mission Time up to one year prior or after liftoff will be displayed.
Double-clicking on the red or green surface of the Mission Elapsed Time window will either Compact the window or Enlarge it to access the Launch Data.
When the Countdown is stopped using the Hold button, the Mission Elapsed Time is displayed with a yellow background.
The gray status bar at the bottom of the enlarged Mission Elapsed Time window always displays the computer's current date and time.
When a Mission Event countdown reaches zero, it can no longer be put on HOLD.
Holding your mouse cursor over any Mission Event will show the Mission Elapsed Time at which that event is scheduled to occur.
A Mission Event label will allow a maximum of 17 characters.
You can save your settings to use later by going to the "File > Save As . . . " menu.  Once you are there, give your file a name and click save.  It can be opened later using the "File > Open . . . " menu.
Click on the Help menu to go the help program.
If you're using Countdown on your computer, send me an email at krislast@bellsouth.net and let me know how you like it.
If you want to hide the buttons on the Event Timers window, go to the "Setting > Hide Controls" menu.  This will make your Event Timers window smaller so that you can use the rest of your computer desktop for other programs.
Go to the "Sim Time" menu on the Mission Elapsed Time window to reset your computer's time to reflect a specific point in your mission.
Most of the Space Shuttles thrust at liftoff is provided by two Solid Rocket Boosters (SRB) which burnout after about two minutes and drop into the Atlantic Ocean.
The Space Shuttle has three main engines called Space Shuttle Main Engines (SSME).  After about the first two minutes of flight, the three SSME's provide the thrust for the Shuttle.
The Space Shuttle Main Engines (SSME) are fueled by Liquid Hydrogen and Liquid Oxygen from the huge orange External Tank (ET).  The ET is jettisoned (dropped) about eight minutes after liftoff.
The part of the Space Shuttle that resembles an airplane is called the Orbiter.
The Space Shuttle uses a system of tracking satellites to communicate with Mission Control.  These satellite are called Tracking, Data, & Relay Satellites (TDRS) and they "hover" in Geostationary Earth Orbit--meaning they stay over the same spot on Earth 24 hours a day.
The Space Shuttle is covered with Thermal Protection Tiles to protect it from the 2,000 - 3,000 degree temperatures generated when it reenters the Earth's atmosphere.  The hottest parts of the Shuttle are covered with special black tiles.
There are 44 Reaction Control System (RCS) engines (or jets as they are called sometimes) that are used to perform small precision maneuvers in space.
The External Tank is actually an aluminum metal case containing two smaller tanks of LH2 fuel and LOX oxidizer.  These two tanks provide all of the fuel and oxidizers for the Space Shutte's three main engines (SSME).
Rockets must carry fuel and oxidizer for their engines.  The fuel is what actually burns (like gasoline in a car).  The oxidizer provides oxygen for the burning.
The Space Shuttle has two types of engines that use hypergolic fuels--the three SSME's and the 44 RCS engines.  Hypergolic fuels are great for space travel because they ignite when mixed.  No spark or heat is necessary to start the burning!
Once the Solid Rocket Boosters (SRB) are ignited, they cannot be shutdown.  They simply have to burn up all of their propellant.  It's sort of like a giant bottle rocket!
Each Solid Rocket Booster has a thrust of approximately 3,300,000 pounds at launch and is 149.16 feet long and 12.17 feet in diameter.
The Space Shuttle travels from 0 to about 17,500 miles per hour within about eight minutes after liftoff!
The Orbiter often flies upside down and even backwards while in orbit.  This protects the crew and the important parts of the Shuttle from pieces of debris called "Space Junk."
One Earth orbit for a typical Space Shuttle takes almost exactly 90 minutes (or one and a half hours).  This means that Shuttle astronauts see a sunrise or sunset every 45 minutes.
To perform major changes in velocity (speed), altitude, or direction while on orbit, the Space Shuttle uses two engines located just above the three Space Shuttle Main Engines (SSME).  These two engines are called the Orbital Maneuvering System (OMS) engines.
Each Orbital Maneuvering System (OMS) engine produces about 6,000 pounds of thrust.
The Orbiter has no power as it approaches the runway to land.  It is the world's heaviest glider at about 250,000 pounds, and it must land it perfectly on the first approach!
You can access Countdown Help by clicking "Help Contents" under the Help Menu or by right=clicking!
Before liftoff, the Space Shuttle is fastened to the ground with only six bolts at the base of each Solid Rocket Booster (SRB).
In the Event Timer Window, you can enter times and keep a countdown for up to ten mission events.  This is useful for tracking times for things like SRB Separation and Re-entry into the Earth's atmosphere.
Holding the mouse over an Event Timer will produce a tool tip that shows the Mission Elapsed Time at which that Event Timer is scheduled to occur.
