MidSTAR-1 (Midshipmen Space Technology Applications Research-1)
MidSTAR-1 is the fourth in a line of space vehicles designed and developed by Midshipmen of the USNA (US Naval Academy) under the sponsorship of the STP (Space Test Program) of DoD. The objective of the satellite is to fly two payloads: ICSat (Internet Communications Satellite) and CFTP (Configurable Fault Tolerant Processor). 1)
The MidSTAR structure is a microsatellite bus of octagonal shape (height of 80 cm, cross-sectional diameter of 54 cm). All eight sides of the S/C are covered with surface-mounted solar cells (16 panels of triple junction GaAs cells) to maximize the available power. The S/C features three interior shelves, which provide area inside the satellite for mounting of components and payloads. Their locations are determined by the dimensions of the payloads and components. These can be varied if necessary, as long as the structure remains within the center-of-gravity requirements. The load-bearing structure of the octagon consists of top and bottom decks.
The C&DH (Command & Data Handling) subsystem uses a Power PC (based on MIP 405) with a Linux operating system. The TCP/IP protocol is being used for all internal satellite communications. MidSTAR uses passive thermal control. Average electrical power of of 27 W is provided; use of Sanyo KR-4400D NiCd batteries. The S/C design life is 2 years. The S/C mass is < 120 kg. 2) 3) 4)
Figure 1: Computer model of the MidSTAR-1 spacecraft (image credit: USNA)
Figure 2: Interior tray structure of the MidSTAR spacecraft (image credit: USNA)
Figure 3: Photo of the MidSTAR spacecraft (image credit: USNA)
RF communications: The downlink frequency is in S-band at 2.202 GHz, the uplink is in L-band at 1.767 GHz (use of BPSK modulation scheme, bit error rate of < 2 x 10-5 ). The MidSTAR spacecraft is being operated by the USNA ground station, Annapolis, MD.
Orbit: The MidSTAR-1 spacecraft (along with the primary payload Orbital Express) will be deployed in the first orbit at an altitude of 495 km and an inclination of 46º.
Launch: The MidSTAR-1 spacecraft was launched on March 9, 2007 (UT) on an Atlas-5-401 vehicle from the Cape Canaveral Air Force Station. MidSTAR-1 was a secondary payload on the STP-1 mission of DoD. The primary payload on this flight was OE (Orbital Express). The other secondary payloads were: CFESat, STPSat-1, and FalconSat-3.
Note: The STP-1 mission had to deal with the deployment of five satellites into two orbital planes at two different altitudes. The Orbital Express (prime payload) and MidSTAR-1 spacecraft were deployed in the first orbital plane at an altitude of 492 km and an inclination of 46º. After two more centaur burns, the remaining ESPA payloads, STPSat-1, CFESat, and FalconSat-3, were inserted into the second orbital plane at an altitude of 560 km and an inclination of 35.4º.
• April 2009: Contact with MidSTAR-1 was lost. The spacecraft ceased transmitting and failed to respond to ground command. The anomaly was attributed to the failure of the battery packs. As a consequence, MidSTAR-1 was declared non-operational. MidSTAR-1 fully supported all onboard experiments for two full years, fulfilling the 100% success criteria (Ref. 3).
• Sept. 7, 2007: Once the batteries recharged sufficiently, the computer restarted successfully. Restart occurred 48 hours after the initial event. No telemetry from the spacecraft or any experiment is available for that 48 hour period. Telemetry indicates that normal operation resumed, but all experiments were left off pending post-event analysis and the development of a plan to bring them back online.
• Sept. 5, 2007: Spacecraft computer froze as a result of unknown influences, most likely radiation-induced upsets. This happened while the spacecraft was in full sun and with the power drains (30 W) on to prevent battery overcharging. Without the computer to cycle the drains off, the spacecraft remained in a continuous negative net power configuration which eventually drained the batteries. When the battery voltage dropped below 8 V, the electronic switches for the drains defaulted to off, returning the spacecraft to positive net power and allowing the batteries to recharge.
• On June 18, 2007, a NASA press release announces success of NCSU.
• The NCSU experiment was turned on May 29, 2007. All experiments are on and delivering data to the PIs.
• The spacecraft is operational after deployment in March 2007.
Sensor/experiment complement: (ICSat, CFTP, MiDN, MEMS, Eclipse, NCSU)
ICSat (Internet Communications Satellite):
ICSat is a collaborative project with NASA. The objective is to demonstrate TCP/IP communications (Internet protocols) on the RF link providing transmission rates of 1 Mbit/s in the downlink and uplink.. The link design employs COTS (Commercial Off-The-Shelf) components. The ICSat requirements call for the following functions/capabilities: 5)
- Link margin must be 10.07 dB on the uplink and 10.70 dB on the downlink
- Must support an uplink frequency of 1.767 GHz and a downlink frequency on 2.202 GHz
- The bit error rate must be better than 2 x 10-5
- The data rate must be 1 Mbit/s on the uplink and on the downlink, using the BPSK modulation scheme
- The link between the spacecraft and the ground station must be completed independent of the spacecraft orientation.
Figure 4: Block diagram of ICSat (image credit: USNA)
CFTP (Configurable Fault Tolerant Processor):
The CFTP is a SOC (System-on-Chip) design emulating three identical processors, using Triple Modular Redundancy (TMR) to mitigate radiation hazards on a radiation tolerant FPGA. With the reconfigurable capabilities of FPGA technology, as newer processors can be emulated, these new configurations can be uploaded to the satellite as software code, thereby actually upgrading the processor in flight. The CFTP payload consists of a PCB (Printed Circuit Board) of size 13.5 cm x 18.5 cm, utilizing a slightly modified PC/104 bus interface. The initial FPGA configuration uses a TMR processor with EDAC (Error Detection and Correction) capability and memory controller circuitry. The PCB is designed with supporting circuitry including a configuration controller FPGA, SDRAM, and Flash memory in order to allow the greatest variety of possible configurations. 6) 7) 8)
Figure 5: Conceptual layout of the CFTP components (image credit: USNA)
Actually, the total chip count is 13, consisting of two FPGAs, 8 memory chips, two power converters and an oscillator. The CFTP utilizes Xilinx RADHARD FPGAs of type SRAM (Static Random-Access-Memory). Supporting the FPGAs are SDRAMs (Synchronous Dynamic Random-Access Memory), Xilinx ISP (In-System Programmable), OTP (One-Time Programmable) PROMs (Programmable Read Only Memory), and EEPROMs (Electrically Erasable PROM) of Intel. The SDRAM provides system memory for the normal functioning of the system as a processor. The EEPROM and PROM provide configuration storage for the two FPGAs. An elaborate interconnection architecture between the CFTP devices provides maximum flexibility in both how the devices are configured and how the devices communicate between each other. The CFTP architecture was designed with maximum flexibility options to support future applications.
Figure 6: Block diagram of the CFTP (image credit: USNA)
MiDN (Micro Dosimeter Instrument):
The objective is to measure the ionizing radiation spectra (primary emphasis on secondary neutrons) for a minimum of two months with a digital, real time, low power, solid state micro-dosimeter. The goal is to obtain radiation quality factors and dose equivalents in order to assess the risks for radiation exposure of an astronaut in space. The basic MiDN instrument is characterized by low mass (< 1 kg), ruggedness (solid-state electronics), low power (< 0.8 W), and low voltages (6 VDC).
MiDN consists of four separate components: three sensor units (external, internal, and absorber) and one electronics unit. 9)
Figure 7: Illustration of the MiDN instrument (image credit: USNA)
MEMS (MicroElectroMechanical Sensor):
MEMS is a USNA-sponsored experiment to test the operation in space of electronically controlled mechanical insulating structures. 10)
Eclipse VED System:
A NASA/GSFC sponsored experiment to test the operation in space of an electrically-controlled optical membrane for thermal control applications. Use of a modular, USB/SpaceWire-driven thermal control system using a solid-state thin-film infrared Eclipse VED™ (Eclipse Variable Emittance Device) system from Eclipse Energy Systems, Inc., St. Petersburg, FL. 11)
Figure 8: MidSTAR-1 Heat Dissipation Test Module with High Emittance (black) and Low Emittance (gold) reference plates as well as two VED devices fully integrated (image credit: Eclipse Energy Systems)
Figure 9: Results of the MidSTAR-1 experiment to measure in-orbit heat dissipation rates of colored and bleached EclipseVEDTM devices (image credit: Eclipse Energy Systems)
Legend to Figure 9: The reference gold plate and black surface present low-e (emissivity=1) and high-e surfaces respectively. The EclipseVED™ is labeled “BC” when in the bleached (low emittance) condition and “CC” when in the colored (high emittance) condition. The reference gold calibration standard is labeled “AuC” and the black surface calibration standard is labeled “BlC.”
From Figure 5, it can be seen that the gold plate has the slowest heat dissipation and the black the fastest. The heat dissipation rate of the colored EclipseVEDTM is closer to that of the black surface, and the heat dissipation rate of the bleached EclipseVEDTM is closer to that of the gold surface. This experiment illustrates the ability of the EclipseVEDTM device to operate in the space environment and be remotely controlled from Earth.
In a SBIR program for the U.S. Air Force, the MidSTAR-1 system was reconfigured for USB control, and the number of devices simultaneously controllable was expanded to 8 per controller module. The unit connects directly to a standard PC USB port, receives DC power from the port and communicates with the host over the USB serial bus. In addition, the controller software is being tailored to detect the characteristics of each panel and subcomponent and to compensate for any loss by monitoring the current across the samples. In the simplest form, if the current is zero, the device is not detected (offline), and, if a short is detected, then the device is considered damaged. In addition, the system will be integrated directly onto a satellite panel such that size and surface-area coverage are optimized for maximum thermal control and/or emittance modulation.
NCSU (Nano ChemSensor Unit):
NCSU is a NASA/ARC sponsored experiment to test the operation in the space environment of a nanotechnology chemical sensor. The goal of NCSU is to demonstrate and validate the use of nanosensors in space flight for trace chemical detection. Nano sensors hold the promise of making MEMS-scale sensor suites for many space exploration missions. This experimental instrument will determine if nano technology can tolerate the micro-gravity, thermal, and cosmic radiation environment of outer space.
The NCSU consists of one PCB (Printed Circuit Board), with connections for an uninstalled/unused daughterboard PCB, one stainless steel gas sample cylinder, one chem-sensor housing containing 32 sensor elements, plus temperature and humidity sensors and three mini-solenoid valves for gas flow control. The PCB contains the electronics to control the flow of gas across the chem sensors, take and store measurements, and transmit the data via RS-422 to the C&DH.
The NCSU's successful operation aboard MidSTAR-1 proved that it senses target chemicals both accurately and repeatedly in space. The NCSU uses a network of tiny carbon nanotubes that are about 10,000 times thinner than a human hair, to sense various gases and their concentrations. 12) 13)
The sensor in orbit was designed to detect trace amounts of nitrogen dioxide (NO2), a common air pollutant. This capability, when combined with the unit's extremely small size, power consumption and heat output makes the NCSU useful to many industries. It could find its way into homeland security applications such as explosives trace detectors.
Figure 10: The NCSU is a laboratory in a box (image credit NASA/ARC)
The NanoChemsensor Unit (NCSU), can sense chemicals and contaminants that may be harmful to astronauts, as well as a wide range of scientifically interesting compounds. The NCSU’s successful operation aboard MidSTAR-1 proved that it can sense target chemicals both accurately and repeatedly in space. The NCSU uses a network of tiny carbon nanotubes that are about 10,000 times thinner than a human hair, to sense various gases and their concentrations. These nanosensors are developed for NASA missions, such as cabin air monitoring for a crew exploration vehicle, in-flight fuel leak detection, planetary exploration, and Earth science observation. This experiment proved that the nanosensors are robust and can undergo the vigorous launch process, and can work in the space environment, including microgravity, radiation, temperature variation, and vacuum. 14)
2) “Midshipman Space Technology Applications Research (MidSTAR-1) Program, Mission Operations Concept Document,” URL: http://www.usna.edu/Satellite/midstar/downloads/ops/MidSTAR-1%20Ops%20Concept.doc
4) “MidSTAR-1,” URL: http://www.usna.edu/Satellite/midstar/downloads/main/PDRfinal.ppt
5) Lloyd Wood, Will Ivancic, Dave Stewart, James Northam, Chris Jackson, Alex da Silva Curiel, “IPv6 and IPsec on a satellite in space,” Proceedings of the 58th IAC (International Astronautical Congress), International Space Expo, Hyderabad, India, Sept. 24-28, 2007, paper: IAC-07-B2.6.06, URL: http://www.cisco.com/web/strategy/docs/gov/wood-iac-07-B-2-6-06-paper.pdf
6) C. A. Hulme,H. H. Loomis, A. A. Ross, R. Yuan, “Configurable fault-tolerant processor (CFTP) for spacecraft onboard processing,” Proceedings of IEEE Aerospace Conference, March 6-13, 2004, Big Sky, MT, Vol. 4, pp. 2269-2276
7) D. A. Ebert, C. A. Hulme, H. H. Loomis, A. A. Ross, “Configurable Fault-Tolerant Processor (CFTP) for Space Based Applications,” Proceedings of AIAA/USU Conference on Small Satellites, Logan, UT, Aug. 11-14, 2003, SSC03-XI-5
8) Dean A. Ebert, “Design and Development of a Configurable Fault-Tolerant Processor (CFTP) for Space Applications,” Thesis, Naval Postgraduate School, June 2003, URL: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA417502
9) V. Pisacane, J. Ziegler, M. Nelson, Q. Dolecek, J. Heyne, T. Veade, A. Rozenfeld, F. Cucinotta, M. Zaider, J. Dicello, “The USNA MIDN Microdosimeter Instrument,” 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, Jan. 10-13, 2005, AIAA-2005-0271, URL: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080029294_2008026522.pdf
11) Kenneth C. Shannon III, Judd Sheets, Howard Groger, Andrew Williams, “Thermal management integration using plug-and-play variable emissivity devices,” Proceedings of SPIE, Vol. 7330, 73300F-1, 2009, 'Sensors and Systems for Space Applications III, edited by Joseph L. Cox, Pejmun Motaghedi, URL: http://188.8.131.52/ft/CONF/16432065/16432076.pdf
12) “NASA MidSTAR-1 Successful Technologies May Be Revolutionary,” NASA, Feb. 19, 2008, URL: http://www.nasa.gov/centers/goddard/news/topstory/2008/midstar.html
13) “MidStar-1 Proves a Tiny Chemical Detector and Heat-Controlling Film,” NASA, Feb. 19, 2008, URL: http://www.nasa.gov/topics/technology/features/midstar.html
14) Rob Gutro, “NASA MidSTAR-1 Proves Revolutionary Technologies,” Goddard View, Vol. 4, Issue 4, March 2008, pp: 8-9, URL: http://www.nasa.gov/centers/goddard/pdf/217739main_GV4_4.pdf
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.