Q1: Is the countdown time really accurate?
A1: We make every effort to make it as accurate as possible. Network delays are a factor is the accuracy of the client. The countdown time to Shuttle Launch should be within approximately one or two seconds of that of KSC Launch Control. NASA does not use this client for any actual launch operations.
Q2: Why does the clock temporarily stop counting, or skip a few seconds periodically?
A2: The Countdown applet is tied directly to live time from KSC Launch Control. The time is being distributed to the network, and experiences delays and losses, as any WAN application would. In order to keep the count distributed realtime, and strive for accuracy, the client applet recieves an update every second, as the clock ticks. Normal network congestion can cause loss of realtime information, such as streaming audio and video. The client will detect the loss, and request new information as needed to track the countdown as closely as possible for current network conditions.
Q3: Why is it necessary to accept a signed applet only if using Internet Explorer?
A3: There is a known bug in the Java VM used by IE, which requires this particular client implementation to use Digitally Signed Code as a workaround to the problem. The client requires NETIO permission to initiate a DataGram Socket. Reference http://support.microsoft.com/support/kb/articles/Q186/0/32.ASP for more details.
Q4: I only see the time -99:23:59:59 CDT and +366:23:59:59 UTC. What is wrong?
A4: The clock relies on network communications between your web browser and the server. A firewall could be blocking this communication. We have relied on high network ports being left open for applications like this. If your companies' policy is to block these ports also, the application will not work. You will still be able to view the countdown thru our text-only version.
Q5: What can be done if other problems are encountered?
A5: Summarize the symptoms in an email to: firstname.lastname@example.org. We will try to address the problem in future updates to the program. Please include details such as browser version, operating system, hardware platform.
Q6: Can I get source code for this applet and host it from my server?
A6: This Java client is still in Beta test and we are not releasing any source code at this time. The applet interacts with server machines at the Kennedy Space Center and the code on both sides is still under development. Due to the security model of Java, the client needs to be downloaded from the machine that is running the server.