MakerSat

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Creator:
Spacefelix
Status:
In Planning
Born On:
14:03, 28 July 2010 (CDT)
Last Updated:
03:34, 06 December 2011 (CDT)

Overview

This page is for the MakerSat project. Makers Local 256's spaceflight effort to put a satellite in space. Will be launched on the MakerLaunch.

Calendar

To Dos

  1. Ask Bill Brown on recommendations for broadcast frequency and power. Last we spoke on 9/2/2010, he recommended a frequency of 900 MHz and 1 Watt. Let's confirm this with him.
  2. High-Altitude Balloon test flight of a radio tracker to determine required broadcast range, power and reception capability.
  3. Decide on architecture of satellite; digital vs analog to balance capability, reliability and weight. See Space & Weight Limitations and Long-Distance Troubleshooting. Design it to our specs for the mission.
    • It has been recommended that this task be started with a study of standard radio circuitry to determine what design would best fit our criteria. We could then modify parts and designs as needed. Strick and ShadowHunter recommend looking up QRP Radio for low-power Ham Radio units.

Status

  • 12/5/2010 - Brimstone suggested the TI MSP430 as another microcontroller option. Stated it had better power control and is cheaper as TI is putting it into the hobbyist market.
  • 12/4/2010 - Spacefelix, C-Tzar, Crashcartpro and Strages discussed satellite design. C-Tzar looked up the weight and temperature specs and made recommendations on microcontrollers that were low-power and lightweight for spaceflight if we choose to use microcontrollers. Crashcartpro inquired about high-temperature epoxies that could act as radiation, thermal and vibration shielding. Strages made mention of the use of dielectric gels to serve this purpose given their toughness, density and ability to function in wide temperature gradients. Strages also showed a small, self-contained, wearable HD digital video camera. It had all the equipment to run; camera, microphone, LiPo battery and fed directly into an SD card. The device weighs 12 grams without its case. Would be something useful to keep in mind for future satellite missions.
  • 12/1/2010 - Spacefelix and Steve Mustakis from Project HALO discussed satellite designs. He gave the recommendation that the high-gain antenna be a helical shape rather than a yagi for durability. He also stated that the tumble method omnidirectional transmission was feasible and very much an inevitable part of satellite deployment in space.
  • 11/22/2010 - Gtpyro gave a recommendation on the satellite power system. Said it could be kept to a simple battery and still have low weight. Pointed to the example of the 3 gram, 1.2V NiMH cell. Also came up with the idea to make directional broadcasting 'omnidirectional' by having the satellite tumble at a high rate. This would take less power and therefore weight, but allow for some degree of omnidirectionality.
  • 11/13/2010 - Discussion with Makers Local 256 members on satellite construction and design. Got recommendations on design for satellite electronics for signal broadcasting and power. Have developed an initial concept for the satellite.
  • 10/16/2010 - Spacefelix spoke to some guys at PhreakNIC 14 about building a space-capable satellite; Strick and ShadowHunter. Strick referred to his friend Charlie ([1]), who works with satellites. He gave recommendations on how to harden against vibration, radiation and thermal extremes. Strick and ShadowHunter gave some advice with Ham Radio transmitter systems that could fit our mission.
  • 9/3/2010 - Discussed with Makers Local 256 members on satellite concepts. Came up with bird tracker concept from CrashCart.
  • 9/2/2010 - Discussed with Bill Brown about transmitting from space and receiving on ground.
  • 7/19/2010 - Bendersgame and Spacefelix discussed some setups for operating a CubeSat. Bendersgame will also try to contact the Indian Space Research Organization (ISRO) for information on the cost of launching cubesats since they have a history doing so. Bendersgame also made the recommendation that we start this project with the TubeSat option since we can gain design, build and fly experience on the cheap before we try the more expensive CubeSat.
  • 6/2010 - Have gathered information and resources on satellite and launch options and costs (monetary and technical).

Current Concepts

  • Goal - To put a 19-gram gross weight satellite in orbit for a period of time per the N-Prize Rules. It will be a simple Broadcast Satellite.
  • Current Satellite Configuration:
    • Small analog or digital transmitter broadcasting a circularily polarized signal over two dipole antennas 90-degrees out of phase from each other. It will broadcast intermittently to save power. It will store power onboard in a supercapacitor or battery and will be powered either by a battery, solar power or electromagnetic induction due to flight through the Earth's magnetic field. The entire unit will be potted in high-temperature epoxy to protect it from vibrations, temperature extremes and radiation. A polyethylene coating may be added for additional radiation protection.
  • Current Mission:
    • Broadcast - Broadcast custom pre-recorded signals over Ham Radio frequencies so anyone can tune in to our flight. <- This is the simplest and lowest-cost mission. We will have our first hackersat fly this one.
  • Notes:

Future Concepts

  • Future Satellite Options:
    • TubeSat - Will be in a decaying LEO (Low Earth Orbit). It will only stay up for a couple of months. But it will only cost $8,000 to buy kit and launch. The best option for us to start out and learn about satellites and spaceflight.
    • CubeSat - Will be in LEO for an indefinite period of time. Cost to build and launch can be up to $50,000. Due to high cost, it would be beneficial to get sponsorships and have other hackerspaces come on board and contribute. We could part out space and mass slots in the satellite for the other spaces to build and integrate their own projects. The option for more capacity, capability and mission duration.
  • Future Missions:
    • Orbital Signal Repeater - A signal repeater in space. Could be used for intercontinental communications.
    • Real-Time Imaging From Space - Webcast a live real-time video or pictures from the satellite. Give an Overview Effect.
    • Biological Payload - Something akin to an EcoSphere or other biological specimens. Would need a way to remotely observe them. Potential science project collaboration.
  • Upgraded MakerLaunch Future Missions - May/will require an upgraded version of MakerLaunch with more payload and/or DeltaV capacity.
    • Time/Data Capsule - Put up a record of something that a future spacefarer may find and decode to understand our culture.
    • TeapotSat - An effort to make true Russel's Teapot Hypothesis.
    • Near-Earth Object/Heavenly Body/Planetary Probe - Land a probe for survey and/or tracking of a Near-Earth Object or other heavenly body or planet.

Challenges

Technical

Launch Environment

Heating due to supersonic flight through the atmosphere, g-loads of ascent and maneuvering, vibration of vehicle. NOTE: It may be possible to do away with extensive shielding for the N-Prize-class MakerSat due to the short-term nature of the competition requirements (9 Low-Earth Orbits at 90 minutes each will take 13-and-a-half hours).

  • Pot the electronics by encasing them in epoxy, especially the electrical connections. The thermal protection for the space environment ought to be sufficient to take supersonic flight heating.
    • Strages recommended dielectric gels as a means to provide shielding for thermal, radiation and vibration conditions. There are several high-temperature dieletric gels sold by Dow Corning that fit our specifications.

Space Environment

Cosmic radiation, space debris, temperature extremes between light and shadow (temperature difference of up to 275 degF). Shielding, radiation and temperature hardening and thermal control will be important.

  • Most vulnerable parts to cosmic radiation would be the microprocessors. Hardened/milspec versions of chips and parts recommended. Will be able to take temperature extremes and radiation. Is it also possible to use a polymer that has a high atomic density for radiation shielding such as polyethylene.
  • Will need to test in high-vibration, extreme temperature and high-radiation environments. Vibration would be a simple test; one could use a simple loudspeaker that can make a wide variety of tones of varying amplitudes. Ratmandu and HAL5's Project HALO have access to high and low-temperature ovens. Alternatively from Preauxphoto, we can use dry ice or liquid nitrogen. Bill Brown also recommends high-altitude balloon flights to test gear in radiation.

Satellite Attitude Control

Launch vehicle and satellite ascent and flight dynamics could induce undesired motion in the satellite by the time it reaches orbit. This would make broadcasting a signal difficult.

  • The signal can be circularly polarized and broadcast over two 1/4-wavelength dipole antennas out of phase by 90 degrees so that signal will be broadcast in all directions. Therefore the satellite is indifferent to tumbling and orientation.

Tracking/Transmitting From Space & Ground Reception

Need to be able to find, acquire and identify the satellite while it is in flight. For communications to assist with tracking, a communications link must cover the distance from ground to orbit and be able to relay sufficient data from the satellite for positive identification and tracking.

  • Directional vs. Omnidirectional transmission - Directional broadcasting requires less power, but will require the satellite to hold a specific attitude with respect to the Earth's horizon. The omnidirectional broadcast will require more power, but no specific attitude required.
    • Gtpyro came up with idea to rapidly tumble the satellite while broadcasting a continuous tone or rapidly repeating tone on a directional antenna. This would give the advantage of directional broadcasting's low power requirement to have a certain broadcast range, but would allow for some degree of omnidirectionality as the satellite would face a receiver multiple times in a pass as it tumbled. The only issue is, for a bi-directional antenna, to not tumble around the axis of the antenna or have the antenna point in orthogonal directions. The tumbling could be achieved by either an off-center release from the final stage of the rocket using either springs or an explosive charge. Steve Mustakis from Project HALO stated that satellite tumble is an expected part of life in space deployment of satellites due to the rocket flight dynamics, inconsistencies in deployment and the low-friction environment of space. We can therefore expect it to do this by default.
  • Brokentrace had the idea of broadcasting to the AMSAT/OSCAR ham radio communications satellites which would relay the signal to ground stations. This is similar to NASA's TDRSS System. This would be a distance of 1000-800 nm sat-to-sat. Would be possible with omnidirectional broadcasting.
  • Bill Brown recommends that we broadcast sideways rather than straight down to make signal acquisition easier. Most ground-based HAM towers side transmit and receive. Also, due to the speed of the satellite, a straight down connection will be hard to achieve since it will only see a point straight down for a very short time. Side transmission gives more time to connect and receive from the satellite. He also is able to provide a high-gain antenna array on the ground for tracking. The approximate maximum distance we will be transmitting over is 100 nm sat-to-ground. He recommends high-altitude balloon flights as a means to test broadcast range to ground stations, satellites, etc.. As a balloon flight would put us above 99% of the Earth's atmosphere, atmospheric attenuation would be mostly accounted for in such a test. To test this further, we can manually attenuate the signal from the satellite to see how low the power can be before our communication elements can't pick it up. It would also allow for testing what orientations give the best signal pickup for various tracking methods.
  • Observing the specifications of Sputnik 1, they broadcast their signal at a power of 1 Watt and at 20.005 and 40.002 MHz. Ratmandu stated that the lower the frequency, the lower the power required to broadcast over a given distance under given conditions. This would assist with reducing the power requirement and therefore mass of the satellite.
  • If all else fails, make a huge radar target (right angle radar reflector) from aluminized mylar that could be inflated like a balloon. Ask organization and people who operate space radars if they can track it. May be difficult to obtain, therefore radio tracking would be preferable.
  • Visual tracking is not a very viable option due to the very specific positions (during dusk or dawn) in which a satellite is visible.

Space and Weight Limitations

Projects must be lightweight, compact and must consume minimal resources. Bare-bones parts and architectures a must. As we are following the N-Prize rules, the gross weight of the satellite; including mission avionics, power source, balance weights and shielding/casing, must not exceed 19 grams total.

  • Mog stated that the simplest thing we can do is all-analog architecture. Confirmed by Ratmandu, a specific signal as well as timing could be hardwired in such an architecture. On the other hand, a digital architecture would have more capability, but may increase weight and power needed.
  • Reduce Power Usage - Use energy harvesting from solar power or the thermal gradient between the light and dark sides of the satellite or induction off the Earth's magnetic field (we are going to be moving 8 km/s through the Earth's magnetic field) to eliminate the weight of batteries and/or have intermittent broadcasts to save power. Strages recommends the use of high power density LiPo cells or supercapacitors as an alternative to batteries for energy storage. It would also be possible to operate intermittently to save power.
    • Gtpyro stated that the power need not be complicated. A battery could be used for our purposes. He cited a NiMH 1.2 V battery that was in the 3 gram range. We will need to research this further to see if it can meet our mass and power requirements.
    • C-Tzar pointed out the Atmel Xmega microcontroller as a low-powered option for the satellite. Brimstone also recommends the TI MSP430 as an option as well.
  • Consider The Mass of Non-Electronics - Due to the need to harden the satellite against the vibrations of launch by potting and radiation and heating by shielding, the electronics; power source, broadcast electronics and antenna, could very well be limited to half the gross weight of the satellite; half of 19 grams.

Long-Distance Troubleshooting

Once it's up there, you can't fix it. You must make it robust and/or allow for remote troubleshooting.

  • Reliability - Must make the system with high reliability. Robust and redundant design needed without breaking the weight and other limits.
  • Testing - Test what you fly, fly what you test. Test your hardware thoroughly under expected and, if needed, possible unexpected flight conditions; it will work up there if it can survive a test down here.

Financial

High Cost of Spaceflight

Achieving orbit on a 1g planet with an atmosphere is a wonder in of itself given the energy required. Getting to orbit on a barely-controlled explosion is always expensive. Therefore, partnerships with people who work with small satellites on the amature level (AMSAT, an amature radio club and a local University CubeSat group) and sponsorships are a must.

  • If there is space on the satellite to put up something (a special object or data), we could charge people/groups to have a slot on the satellite. An example would be if we had a digital architecture for the broadcaster, it could contain custom messages from various people/groups.

Regulatory

  • Regulations on Broadcasting - As the satellite will be broadcasting a radio signal, we must follow the appropriate regulations for the respective type of radio frequency.
  • Regulations on Spaceflight - As the satellite will be in orbit, we will need to follow the rules set down for spaceflight by either the FAA, NASA or other regulatory body.

People

Resources

TubeSat

CubeSat

Hardware

Communications Options

Etc.

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