Presentation on theme: "1. 2 The primary launch date is March 30th at 10:50 PM EDT. There is also a backup date of April 3rd at 9:40 PM EDT. Here is a revised sequence of events."— Presentation transcript:
2 The primary launch date is March 30th at 10:50 PM EDT. There is also a backup date of April 3rd at 9:40 PM EDT. Here is a revised sequence of events for our mission assuming the March 30th primary launch date: Falcon 9 liftoff (10:50 PM) Falcon stage separation (10:53 PM) Falcon 2nd stage engine cutoff and Dragon Separation (10:59 PM) KickSat deployment (11:53 PM) KickSat radio beacon power-on (12:43 AM) Sprite deployment (11:53 PM on April 15th) Telemetry packets in AX.25 format on MHz with 1200 baud AFSK modulation
3 KickSat CubeSat to Deploy Small Earth-Orbiting Satellites
4 The KickSat project was founded in 2011 by members of the Space Systems Design Studio at Cornell University. It is an outgrowth of research on small spacecraft that has been conducted there since The current project lead is Zac Manchester, a PhD student in Aerospace Engineering.
5 KickSat is being planned as a technology demonstration mission for the Sprite spacecraft. It is a 3U CubeSat that will house a 1U avionics bus and a 2U Sprite deployer. KickSat will be launched through NASA's ELaNa program and will carry over 100 Sprites into an orbit with an altitude between 300 and 350 kilometers where they will be released as free- flying spacecraft.
6 The Sprite is a tiny (3.5 by 3.5 centimeter) single-board spacecraft. It has a microcontroller, radio, and solar cells and is capable of carrying single-chip sensors, such as thermometers, magnetometers, gyroscopes, and accelerometers. To lower costs, Sprites are designed to be deployed hundreds at a time in low Earth orbit and to simultaneously communicate with a ground station receiver.
8 The Sprite ChipSat
12 Programmer and Development Kit
14 The Sprites will be deployed by a timer exactly 16 days after KickSat is deployed from the launch vehicle. The timing was arranged with NASA to avoid interference with ISS operations. Once KickSat turns on its radio, you should be able to pick it up with very basic Ham radio gear. It will be transmitting telemetry packets in AX.25 format on MHz with 1200 baud AFSK modulation. I'll post KickSat's orbital elements here and on the project wiki, which will also have more information on setting up a receiving station.
19 The Sprite has a UHF (437 MHz) transceiver capable of transmitting at a maximum power of 10 dBm (10 milliwatts). That's not a lot of power when you're trying to receive a signal from 500 kilometers away. Comparison: GPS signals are broadcast with about 50 Watts of power from about 20,200 kilometers away. GPS signal received on the ground will have a power of about -135 dBm (that's 28 femtowatts), while the Sprite signal will have around -129 dBm (120 femtowatts) of power. The Sprite signal is actually four times more powerful than a GPS signal when received from Earth!
20 The problem with receiving a weak signal is not so much that it's weak - we can always run the signal through an amplifier - it's that signals are always awash in a constant background of noise. When we run a signal through an amplifier in real life, the noise comes along for the ride and also gets amplified. The result is that we're stuck with the same ratio of signal to noise after the amplifier as we had before. Noise makes it hard for a receiver to tell if a given bit is a zero or a one and we end up with lots of errors in our received signal.
21 We're borrowing some signal processing tricks used by GPS and cell phones. It is called Forward Error Correction (FEC). The whole FEC process can be abstracted away and thought of in terms of "signal processing gain" in the same way we think about antenna gain or amplifier gain. But you never get something for nothing. For a given transmitter bit rate, our effective data rate is lower. We've traded a slower data rate for some extra gain.
RF Before Correlation
24 Yagi Antenna (e.g. Arrow Antenna 440-5) Low-Noise Amplifier (e.g. Down East Microwave L432LNA, RFBay LNA-440, or dg0ve LNA70-1) Software-Defined Radio Interface (e.g. an RTL Dongle) A laptop running SDR# or GNURadio
25 Today we received signals from two Sprites at a distance of 37 kilometers (23 miles) with an additional 23 dB of attenuation between the antenna and LNA (low noise amplifier - the first stage of the receiver). That works out to an equivalent distance of about 532 kilometers (325 miles), or roughly the same as listening to an orbiting Sprite at 38 degrees elevation above the horizon.
26 I was standing 25 miles to the north in Mountain View (roughly where the arrow is pointing in the picture) with the receiver.