On may 25th 2012 the SpaceX Dragon capsule became the first commercial spacecraft to ever dock with the International Space Station (ISS). For decades NASA space shuttle carried the ISS into orbit, but with the shuttle program retirement there is a need for a new era of space travel. With several resupply mission scheduled in the near future SpaceX will get lots of practice so they can refine their designs and code in time to be ready to fly humans by 2015. We wanted to pay tribute to the engineers and scientist at SpaceX and let them know we're cheering them on every step!
Falcon Rocket
We used a SpaceX Falcon 9 and Dragon Model Rocket Kit as the rocket and capsule in our setup. The rocket was attached to two guide rods made from copper wire and a DC motor at the top of the tracks launched the Falcon 9 via an attached string. At the beginning of the launch sequence we had a red electroluminescent (EL) pad to represent the massive amounts of fuel that the Falcon 9 needs for successful delivery of the Dragon Capsule. We used guide rods to make the rocket “wobble” as it ascended, as well as to make the launch more interesting. The launch is stopped by using a Hall Effect sensor mounted near the top of the launch tracks, which detects the magnetic field of a magnet we mounted inside the tip of the rocket.
Dragon Capsule
The capsule was also made out of the same SpaceX Model Rocket Kit, and it is initially hidden behind a black box. Once the Falcon 9 rocket launch is complete, the capsule separates from the rocket at begins its journey to the International Space Station (ISS). Its propelled by another DC motor toward the ISS model. The ISS model is made from folded paper kit and mounted in front of the pulley which pulls the Dragon capsule close for docking.
EL Wire
Once the Dragon capsule docks with the ISS, a confirmation signal is sent back to earth, which is represented by 4 strands of EL wire. Each strand is controlled to light up one after the other with about one second of delay between. This was done to also demonstrate electromagnetic propagation and that RF waves take time to travel.
Mission Control
Once the last strand of EL wire is lit, an LED is lit on the Mission Control Panel. This LED is monitored by a LEGO MINDSTORMS NXT program and light sensor. When the light level goes above a threshold the motor turns cause our LEGO SpaceX engineers to rejoice! This pulls a string which releases the Hotwheels car for the Mars Curiosity section.
Control System
Behind the scenes, all the motors and lights were controlled by LabVIEW through an Arduino with the LabVIEW Interface for Arduino Toolkit. All the code was written in LabVIEW. The motors were connected to a DC Motor Shield and the EL Wire was connected to an EL Wire Driver Shield, both of which were connected and stacked onto the Arduino. This allowed us to control all the devices with digital signals through the Arduino. The Hall Effect Sensor was connected to one of the Analog Input pins on the Arduino, and the value was read as the rocket launched, and a loop waited for the signal to reach above a set threshold. The motor speed as well as the strobe effect on the EL Wire Launch Pad were both controlled by the PWM digital output pins on the Arduino which allowed for a pseudo-variable voltage.
More information about the project can be found here
