To the average observer, SpaceX's Falcon 9 rocket, that ferried astronauts Doug Hurley and Bob Behnken from earth to the international space station (ISS) might seem like just another majestic spacecraft. However, to an electrical engineer, it is a spectacular feat of engineering ingenuity.
The spacecraft, which lifted off from Launchpad 39A at NASA's Kennedy Space Center consists of the Crew Dragon Demo-2 capsule, detachable from the primary and secondary stages of a Falcon 9 Block 5 rocket.
Electrical Components in SpaceX's Falcon 9 Spacecraft
Falcon 9 is a reusable two-stage spacecraft capable of carrying humans and payloads into orbit. The rocket comprises a host of electronics and power systems including the following:
According to SpaceX's Falcon Users Guide, Falcon 9's avionics has a "three-string, fault-tolerant architecture designed to human-rating requirements."
These include in-flight computers, GPS receivers, inertial measurement units (IMUs), proprietary controllers for vehicle control, and more. Falcon 9 launch vehicles utilise modern computing/networking technology to enhance the rocket's performance and reliability.
SpaceX's Falcon 9 reusable rocket. Image Credit: SpaceX.
Radio-Frequency (RF) Systems
Falcon 9 contains a broad range of RF systems including S1TX1 telemetry transmitters with PCM/FM modulation, a GPS receiver and Iridium/GPS trackers with BPSK DSSS and BPSK/QPSK/BPSK DSSS modulation respectively.
Other features include an S-Band BPSK receiver with BPSK modulation and Radar altimeters that operate using frequency-modulated continuous-wave (FMCW) modulation.
Electrical connectivity between Electrical ground support equipment (EGSE) and the Falcon 9 payload is via Falcon launch vehicles. The launch vehicles also provide electrical interfacing via two in-flight disconnect points at the payload separation plane.
Connectivity is via 37 or 61-pin electrical connectors, or customer provided connectors. SpaceX utilises ground harness in several interfaces of the vehicle, including junction box to launch vehicle transporter-erector and transporter-erector to the second stage.
Astronauts Doug Hurley and Bob Behnken aboard the Crew Dragon Demo-2 capsule. Image Credit: SpaceX/Twitter.
For protecting electronic systems from voltage surges due to lightning, the Falcon 9 launch pads at NASA's Kennedy Space Centre utilised overhead wire lightning protection systems.
These systems provided a safe path for discharging overvoltage, minimising the risk of component damage or electrocution of personnel. Additionally, lightning protection systems prevented side flash and electromagnetic coupling in flight hardware and ground systems.
More Flexible Controls: Manual Plus Auto
The Crew Dragon Demo-2 is the first spacecraft to include touchscreen control panels for astronauts to take the "wheel" where necessary. On its website, SpaceX offers a virtual flight simulator much similar to what is onboard the actual crewed capsule. More flexible controls will allow the astronauts to override automatic systems whenever the need arises.
Setting the Pace for a Burgeoning Industry
SpaceX's Falcon 9 rocket, including the Crew Dragon Demo-2 capsule, is indeed a remarkable piece of hardware. Electrical engineers, alongside other technical professionals, worked hard on designing a spacecraft that should stand the test of time.
With a successful launch to the ISS in about 19 hours and fully reusable elements, Elon Musk's brainchild has opened up a new era of cheaper and more frequent space flights.