1. Computers and Space Travel January 31, 2016 Kevin Tang

2. Apollo 11  First space expedition  Launched on July 16, 1969  Mission lasted for 8 days, 3 hours, 18 minutes  Crew members  Neil A. Armstrong  Edwin E. “Buzz” Aldrin Jr.  Michael Collins

3. Getting Man on the moon  Computer called Apollo Guidance Computer (AGC)  Real time operating system  About 64 kb  Operated at 0.043mhz  Used to help guide the Apollo to the moon and back

4. Luminary  About 300 people worked on developing this software for 7years  Coded in MAC (MIT Algebraic Compiler)  Converted by hand into assembler language so that the computer can understand  The assembler code is then fed into AGC with punch cards  Luminary version 99 helped land the Apollo 11 mission but Luminary was complete later at Luminary version 209.

5. Trouble with Luminary  One program would occasionally erase another program’s data during critical moments.  This was one of the hardest problem to debug  Program were run according to their priority  And when a program took too much resource or time, Luminary would simply throw away the current process and move onto the next one

6. Trouble with Luminary  During the moon landing, the Lunar module threw some errors at the astronauts.  The two alarms that were triggered caused an enormous delay in the autopilot guidance command.  The delay caused an entire minute of landing adjustment to not run.  This may not sound long but a stabilizing command would be issued every 10 th of a second by the autopilot program.  That’s 600 stabilizing command that were never issued by the computer.

7. Moon Race  While the United States was preparing for their Apollo 11 space expedition the Soviet Union was secretly competing with the U.S (Luna 15).  The Soviet Union’s space craft ran into some major failures that caused them to abort the maned mission  They then tried by the first one to bring back lunar material to Earth by sending a probe.  On July 13, they launched Luna 15 but during the landing, a malfunction caused the probe to crash two hours before Apollo 11 launched

8. SpaceX Falcon 9  Uses a version of Linux  Most of the software are written in C++.  Has redundant flight computers for fault tolerant design  The rocket is controlled by three voting computers.  The first stage rocket of the Falcon 9 is the first, first stage rocket to land upright back on earth to be reused.

9. Voting Computer  Uses voting logic  Used to monitor and determine when and by how much to regulate each component linked to it.  For example:  Circuit breakers is a type of voting logic that does not involve computer  In the case of Falcon 9, the voting computer was used to regulate the thrust each rocket.

10. Sources  https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html  https://www.netjeff.com/humor/item.cgi?file=ApolloComputer https://www.netjeff.com/humor/item.cgi?file=ApolloComputer  https://en.wikipedia.org/wiki/Redundancy_(engineering)#Voting_logic https://en.wikipedia.org/wiki/Redundancy_(engineering)#Voting_logic  http://www.spacex.com/about/capabilities http://www.spacex.com/about/capabilities  http://www.spaceflightnow.com/falcon9/001/status.html http://www.spaceflightnow.com/falcon9/001/status.html