SMDC-ONE (Space & Missile Defense Command-Operational Nanosatellite Effect)
The U.S. Army SMDC/ARSTRAT (Space & Missile Defense Command/Army Forces Strategic Command) of Huntsville, AL (Redstone Arsenal), is developing an 8 nanosatellite (3U CubeSats) communication demonstration mission. The primary objective is to receive data from a ground transmitter and relay that data to a ground station. This is referred to as tactical BLOS (Beyond-Line-Of-Sight) communications. The intent of this technology demonstration is to build a number of identical satellites and deploy them together into LEO (Low Earth Orbit) to simulate enhanced tactical communications capability and evaluate nanosat performance.1) 2)
The 3U CubeSat form factor was selected as the appropriate satellite mass class for several reasons. These lightweight payloads have numerous piggy backing opportunities and invite the development of a low-cost launcher designed for nanosatellites. For SMDC-One, the design life is one year on orbit while the minimum success criteria is six months.
In 2009, the SMDC-ONE program completed the construction and testing of one qualification nanosat which will be followed by eight flight nanosats. The qualification unit underwent rigorous shock, random vibration and thermal-vacuum testing at the prime contractor and NASA locations. Thermal balancing and antenna deployment tests were conducted during thermal-vacuum testing at the prime contractor’s location. Radio frequency characterization testing was conducted at US Army facilities.
Figure 1: Illustration of the SMDC-ONE nanosatellite (image credit: SMDC)
SMDC-ONE concept of operations: The objective of the first flight demonstration involves a single SMDC-ONE satellite which will receive its tasking from the FOB (Forward Operating Base) or from the C2 (Command and Control) station as shown in Figure 2. The early SMDC-ONE satellites do not have onboard GPS, so the tasking and timing information will be provided from the C2 station after preliminary on-orbit checkout of the satellite occurs. The program has two C2 stations, one at USASMDC/ARSTRAT Headquarters in Huntsville, AL and the other at USASMDC/ARSTRAT’s Battle Laboratory in Colorado Springs.
Figure 2: SMDC-ONE Operational View 1 (OV-1), image credit: SMDC
The nanosatellite is being built by Miltec Corporation of Huntsville, AL, as prime contractor. The nanosatellite conforms to a 3U CubeSat standard in size (10 cm x 10 cm x 30 cm). The mass is ~ 4.5 kg. 3) 4) 5)
For future missions, the Army is considering developing nanosatellites with on-board GPS capability, S-band communications link for increased data transmission, inclusion of a software defined radio for greater transceiver frequency flexibility, and modification of the radios to increase the available volume for payloads.
Figure 3: Subsystem layout of SMDC-ONE (image credit: SMDC)
RF communications: A custom UHF-VHF transceiver is used used for communications. There are four VHF transmitting antennas on one end of the satellite and four UHF receiving antennas on the other end.
Figure 4: Photo of the SMDC-ONE nanosatellite (image credit: Miltec)
Launch: The SMDC-ONE nanosatellite was launched as a secondary payload to the demonstration flight of the Dragon C1 spacecraft (primary payload) of SpaceX on Dec. 8, 2010. Launch vehicle: Falcon-9, launch site: Cape Canaveral, FL, USA.
Orbit: Non-sun-synchronous orbit, low altitude of ~ 300 km apogee x 275 km perigee (due to the requirement of the primary payload), inclination = 34.5º, period = 88.1 minutes.
After deployment from P-POD (Poly-Picosatellite Orbital Dispenser), it is expected that SMDC-ONE will remain in orbit for approximately 30 days before dropping out of orbit. Because of its small size and weight, SMDC-ONE is expected to be destroyed during reentry into the atmosphere.
• The nanosatellite remained in orbit for 35 days (reentry on January 12, 2011), providing data on its operations, and proving its ability to receive text and images from a ground sensor, and then to relay that data to a ground station. 6) 7)
SMDC-ONE Flight A remained functional until its reentry on 12 January 2011. SMDC-ONE-A achieved TRL-7 (Technology Readiness Level 7) and provided a firm foundation for future Army nanosatellite development (Ref. 10).
Figure 5: Apogee, perigee trending vs days on orbit (image credit: (image credit: SMDC)
The primary objective of this maiden flight was over-the-horizon communications of unattended ground station (UGS) data.
The performance of this first satellite and ground stations at Redstone Arsenal and SMDC's battle laboratory in Colorado Springs, CO, far exceeded expectations of the project. Tests were also conducted using data from UGS (Unattended Ground Stations). Initially, it was thought those experiments wouldn't be possible until later launches. During SMDC-ONE's flight, a UGS was also set up in a parking lot at Redstone Arsenal which relayed data and pictures to the satellite overhead and on to the personnel in Colorado. 8)
Next steps: For SMDC-ONE program's next steps, two SMDC-ONE nanosatellites will undergo software modifications to make them compatible with Army field radios. A third SMDC-ONE will be modified to incorporate a SDR (Software Defined Radio) and certified encryption hardware, under the sponsorship of the ORS Office. All three of these satellites are expected to fly in 2012 (Ref. 10).
• After being dormant for 30 minutes, the nanosatellite deployed its receiver antennas. Even though in a tumbling mode, the satellite contacted the ground station at USASMDC/ARSTRAT on Redstone Arsenal, AL, and provided "state-of-health" data.
• About 45 minutes after liftoff, SMDC-ONE deployed from the Falcon 9 trunk unit located in the second stage of the rocket and was placed into a low earth orbit. 9)
The ground segment consisted of a laptop computer, radio/RF unit, antenna rotator and antennas. These stations were designed to be highly transportable and easy to use. The ground station has two operational modes: Command and Control (C2) and UGS (Unattended Ground Sensor). 10)
Figure 6: SMDC-ONE concept of operations (image credit: SMDC)
Most of the ground station functionality can be accessed in the C2 mode. C2 mode allows the user to collect satellite telemetry data, send satellite tasking requests, retrieve relayed data, and extract ground sensor data. In C2 mode, the ground station initiates all communications with the passing satellite in the form of manual or automated script commands. Typical operations in this mode include requesting information from the satellite or scheduling future satellite operations; i.e., the C2 mode is the satellite tasking mode.
The UGS mode requires one station to be the C2 tasking agent and one ground station serves only as a passive host of data which can be read by the passing satellite. All communication between the satellite and the station in UGS mode is initiated by the satellite.
Both the ground radio and the antenna rotator are controlled through applications on the laptop computer. Prior to a typical satellite pass the ground station user would use the Mission Planner application to generate Doppler tables and pointing tables to tune the radio and antenna rotator respectively. The operator would then switch to C2 or UGS mode and set up the mission. Typically the operator would initiate transmission at approximately 5 degrees elevation and receive confirmation of a good transmission between 7-10º elevation depending on terrain masking, slant range and other factors.
1) David J. Weeks, A. Brent Marley, John R. London III, “SMDC-ONE: An Army Nanosatellite Technology Demonstration,” Proceedings of the 23nd Annual AIAA/USU Conference on Small Satellites, Logan, UT, USA, Aug. 10-13, 2009, SSC09-X-3
2) SMDC-ONE, Nanosatellite beyond line-of-sight communication,” Army Space Journal, April 27, 2009, URL: http://www.smdc-armyforces.army.mil/Pic_Archive/ASJ_PDFs/ASJ_VOL_8_No_3_Fall_2009_Article_7.pdf
3) Bart Graham, Byron Schrader, Brian Pletcher, “US Army Space and Missile Defense Command Operational Nanosatellite Effect (SMDC-ONE),” 2009 CubeSat Developers' Workshop, San Luis, Obispo, CA, April 22-25, 2009, URL: http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2009/5_Missions_1/4_Graham-SMDC.pdf
5) John R. London III, A. Brent Marley, David J. Weeks, “Army Nanosatellite Technology Demonstrations for the Tactical Land Warfighter,” 27 Army Science Conference, Orlando, Florida, November 29 - December 2, 2010, URL: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA534645&Location=U2&doc=GetTRDoc.pdf
6) Kari Hawkins, “Flying into orbit in small package,” Jan. 26, 2011, URL: http://www.army.mil/-news/2011/01/26/50875-flying-into-orbit-in-small-package/?ref=news-science-title6
7) John Cummings, “Army nanosatellite completes first flight,” Jan. 14, 2011, URL: http://www.army.mil/-news/2011/01/14/50426-army-nanosatellite-completes-first-flight/
8) Kenneth Kesner, “SMDC: Test of Army's first satellite in over 50 years shows the small orbiter can help soldiers,” Jan. 20, 2011, URL: http://blog.al.com/huntsville-times-business/2011/01/satellite.html
10) John R. London III, Mark E. Ray, David J. Weeks, A. Brent Marley, “The First US Army Satellite in Fifty Years: SMDC-ONE First Flight Results,” Proceedings of the 25th Annual AIAA/USU Conference on Small Satellites, Logan, UT, USA, Aug. 8-11, 2011, paper: SSC11-III-5
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.