STARSHINE (Student-Tracked Atmospheric Research Satellite for Heuristic International Networking Equipment)
STARSHINE is a US cooperative program of small optically reflective spherical student satellites, designed and built by NRL/NCST (Naval Research Laboratory/Naval Center for Space Technology). They are being deployed by NASA from Hitchhiker canisters in Space Shuttle cargo bays, as well as from an Athena unmanned launch vehicle, into highly inclined low earth orbits at a rate of once every year or so.
The principal objectives of the project Starshine are educational and motivational. If students help “build” the spacecraft (by polishing its mirrors), they should be more excited about tracking it and using it to measure upper atmospheric density and the response of that region of the atmosphere to solar storms. - Self-contained mirror polishing kits, containing two mirror blanks each, were prepared by project volunteers and mailed to 1050 schools around the world. Nearly 1800 mirrors were polished by 25,030 students in some 700 schools in 18 countries. 1) 2) 3) 4) 5) 6) 7)
Table 1: Overview of Starshine missions flown
Starshine-1 is an optically reflective small passive satellite with no moving parts or electrical components. It is spherical with an outer diameter of 47.5 cm, the S/C mass is 39 kg. The shell is made of aluminum, the exterior is covered with 878 aluminum mirrors that are 25 mm in diameter. The Starshine structure consists of the following basic components: two hemispherical domes (two top dome has 499 mirrors, the bottom dome 399 mirrors), and an equatorial disk (to join the two hemispheres).
Launch: Starshine-1 was launched by Shuttle flight STS-96 (launch May 27, 1999 - deployed June 5, 1999), with the objective to provide educational observations for students around the world. More than 1,000 schools across America and the world have helped construct the satellite and participated in the project. Although only slightly larger than a basketball, Starshine-1 is covered by 878 highly polished mirrors that make it visible from the ground. It was released from Discovery on June 5, 1999, near the end of the STS-96 mission after the Shuttle had left ISS (International Space Station).
Orbit: The initial orbit of the Starshine after release was 387 km in altitude and 51.6º in inclination (decaying circular orbit), orbital period of 90 minutes. Note: reentry of Starshine-1 on Feb. 19, 2000.
Figure 1: Gil Moore, the Project Starshine Director, with the Starshine-1 mockup (image credit: Project Starshine)
Figure 2: John Vasquez of the Naval Research Laboratory prepares Starshine-1 for vibration test (image credit: Project Starshine)
Satellite operation: The twinkling satellite was visible to the naked eye against the star background, during certain recurring morning and evening twilight periods, to observers around the world between the latitudes of ± 60º. Student observers around the world recorded the position, of the tumbling (sunlight reflecting) satellite and provide this information to the project's website. They measured right ascension and declination at precise times by reference to known stars, and they were also recording the precise time of their observations by the use of stopwatches synchronized with international time signals. Some observers used GPS receivers to measure the latitude, longitude and altitude of their observing sites. They posted their observations and station locations on the Starshine web site to permit computation of the classical elements of the satellite's orbit by the angles-only-method of Laplace. The changes in the decaying orbit were used to calculate the density of the upper atmosphere. Student investigations were also made to the effect as to how the density of the upper atmosphere varies with solar activity.
It turned out that Starshine did initially not tumble as expected after deployment from HES (Hitchhiker Ejection System). The rate of visible flashes produced by the mirrors varied from once per 15 seconds to once or twice per pass. The situation improved in the latter phases of the mission as the satellite descended into the atmosphere (the denser air causes a torque on the S/C). Re-entry of Starshine-1 occurred on Feb. 8, 2000 when it was consumed by aerodynamic heating at an altitude of about 80 km above the Atlantic Ocean off the coast of Brazil. The project Starshine observers webpage is at NASA/HQ under: http://spacekids.hq.nasa.gov/starshine/
Figure 3: Size comparison of Starshine spacecraft (Project Starshine)
Starshine-2 is of the same size and mass as Starshine-1. The 846 mirrors that cover the outside surface of this satellite have been polished by students in 26 countries. These mirrors have been coated with a scratch-resistant, anti-oxidizing layer of Silicon Dioxide by optical technicians at the Hill Air Force Base. At NRL, the mirrors were installed onto the spacecraft. The satellite has the same size and mass as Starshine-1. This time around, it also contains a special cold-gas spin system to rotate the satellite at 5º/s to enhance the rate at which sunlight will flash from its mirrors. In addition, the satellite carries twenty laser retro-reflectors, distributed evenly across its surface, to permit tracking by the International Satellite Laser Ranging Network. 8)
Figure 4: Photo of Starshine-2 (image credit: NRL, Project Starshine)
Launch: Starshine-2 was launched on Shuttle flight STS-108 Endeavour (Dec. 5 to 16, 2001) into an orbit of 387 km altitude with an inclination of 51.6º.
Status of mission:
• On Dec. 16, 2001, Starshine-2 was deployed from the Shuttle Endeavour's payload bay. As soon as the satellite drifted a safe distance from the shuttle, a nitrogen gas system fired and set the satellite spinning. 9)
Figure 5: Photo of Starshine-2 as it was deployed from the payload bay of Endeavour during STS-108 (image credit: NASA)
• Starshine 2 reflects sunlight and looks to sky watchers on Earth much like a pulsing 1st-magnitude star. Students and scientists plan to track the pair by monitoring their flashes, and so learn how satellite orbits decay in the outermost layers of Earth's atmosphere.
• Reentry of Starshine-2 into Earth's atmosphere on April 26, 2002.Starshine 2 orbited Earth during the second peak of an ongoing double-peaked solar maximum. As a result of the solar maximum, Earth's atmosphere is "puffed up" like a marshmallow over a campfire leading to extra drag on Earth-orbiting satellites. 10) 11)
Figure 6: Starshine 2's orbital decay curve (image credit: NASA)
Starshine 3 is essentially a passive satellite as are all other satellites in this series. The primary mission of Starshine-3 is to measure atmospheric density as a function of altitude. This is done by tracking the satellite's orbital decay. Tracking is accomplished using the SLR (Satellite Laser Ranging) technique and visual sightings against a star field.
The structure of Starshine-3 is a sphere of 94 cm in diameter and a mass of 91 kg (microsatellite class). The structure consists of two spun aluminum shells and an aluminum sheet metal thrust cone supporting an aluminum honeycomb payload deck. Starshine-3 is covered with about 1500 student-polished mirrors; in addition, twenty laser retro-reflectors are mounted on its surface. The spacecraft was built and integrated by NRL with assistance from Calhoun Community College in Decatur, Alabama, and the C. F. P. Paul Rousseau school in Drummondville, Canada.
Table 2: Overview of Starshine-3 parameters
Figure 7: Photo of Starshine-3 (image credit: Project Starshine)
Launch: A launch of Starshine-3 took place on Sept. 30, 2001 on an Athena-1 vehicle from the Kodiak Launch Complex on Kodiak Island, Alaska. The entire launch payload consisted of four small satellites: Starshine-3, PICOSat, a technology demonstration microsatellite of DoD/AFRL, PCSat (Prototype Communications Satellite) a microsatellite designed and built by Midshipmen of the United States Naval Academy (USNA), Annapolis, MD, and SAPPHIRE (Stanford AudioPhonic Photographic IR Experiment) of Stanford University. The launch of all satellites represented also the inauguration of launch services from this site.
The launch sequence of the mission was designed in such a way as to deploy first the primary payload, PICOSat, into an 800 km orbit at an inclination of 67º, followed by successive deployments of SAPPHIRE and PCSat (with no specific requirements on orbit). Then the OAM (Orbital Adjust Module) of the launch vehicle performed an orbit change maneuver to lower the orbit from 800 km to 500 km circular altitude (requirement of Starshine-3). At about this altitude, the Starshine satellite was deployed.
Orbit: circular orbit, altitude ~ 500 km, inclination = 67º. The higher orbit implies also a longer lifetime of the satellite.
Communication system: One of Starshine-3 primary objectives is to involve more school children in radio science. As part of this mission, science data from experimental solar cells is downlinked in a manner that permits schools and radio amateurs to participate in collecting the data.
For this reason, the downlink has been designed for compatibility with the affordable Kenwood THD-7 hand-held radio terminal and also for compatibility with other amateur radio terminals. The THD-7 radios contain built-in AX.25 Terminal Node Controllers (TNCs) and RS-232 ports. Consequently, they can receive Starshine-3 downlink signals directly. Schools that purchase THD-7 or similar radios will be able to receive the Starshine 3 signals with their identifying “STRSHN3 N7YTK” data header very simply. This helps the students to see that they really are receiving data from the satellite for which they polished mirrors. They are able to forward the received data to the Starshine Project Internet site. This should be an excellent science and technology project for the school children. 12)
The Starshine-3 downlink uses VHF-band communications at 145.825 MHz (data rate of 9.6 kbit,s, FSK modulation, NRZ encoding). The AX.25 packet protocol is being used. RF communications (amateur standard) between S/C and the ground, consists of a telemetry transmitter, a command receiver, rechargeable batteries (IMPS), a secondary solar array, signal-conditioning circuitry, and an antenna. The data is transmitted to ground receiving stations at the University of Alaska, Fairbanks, the US Naval Academy, Annapolis, MD, Santa Clara University in Santa Clara, CA, and to numerous amateur radio stations around the world.
Figure 8: Starshine-3 final half-orbit in orange (image credit: NASA) 13)
The reentry of Starshine-3 occurred on Jan. 21, 2003.
• Advanced separation system by the name of Lightband (developed by the Planetary Systems Corporation, Silver Spring, MD). This is a low-mass and low volume non-pyrotechnic separation system that imparts a spin to the deploying satellite. Shock loads at separation are low due to small pre-loads.
• An experimental stand-alone power supply called IMPS (Integrated Microelectronic Power Supply) provided by NASA/GRC. IMPS provides the capability of power generation and power storage for microelectronic applications - by combing a thin-film photovoltaic array with a thin-film lithium-ion battery. A technological objective of IMPS development is to have all components seamlessly integrated on a common substrate using thin-film batteries and thin-film solar cells. The Starshine-3 IMPS implementation represents simply the first step toward this goal. 16)
The STARSHINE-3 IMPS package (5 IMPS test units) consists of a solar array, a rechargeable battery, and power management electronics all fitting onto a circuit board of about 6.5 cm2.. Each IMPS is designed to deliver a constant 20 μA current through a 1000 Ω platinum temperature sensor. A solar array is 1cm2 in size, a monolithically interconnected module (MIM) of seven GaAs solar cells connected in series. The array output is nearly 7 V and can deliver up to 3 mA of current to the load and/or charging of the battery. - The IMPS energy storage is a high capacity 3 V manganese/lithium-ion rechargeable battery (capable of powering the load for 90 days without recharging). The battery is a Panasonic ML2020 with a capacity of 45 mAh rated for a continuous 100 μA load. The power management electronics consists of a micro-power voltage regulator and a blocking diode. - The new system is expected to find significant use in picosatellites for powering sensors, serving as battery backup for memory circuits and increasing design flexibility by having power available separate from the central bus.
Figure 9: Solar cell string and a IMPS mounted on the Starshine-3 (image credit: NASA)
• STARSHINE-3 serves also as a testbed for demonstrating triple-junction solar cells. These cell types are considered the first GaInP/GaAs/Ge solar cell modules flown in space made by Emcore Corporation. The solar cells are used on STARSHINE-3 to power the communication system (electronics and transmitter). triple-junction cells made by Emcore Corporation. Each solar cell is essentially three solar cells monolithically connected in series and stacked vertically on one another. The top cell is a GaInP cell that absorbs only blue light (300 nm to 650 nm in wavelength). The GaAs middle cell collects light from 650 nm to 900 nm, and the Ge bottom cell collects light beyond 900nm. This spectrum splitting technique greatly improves the efficiency over conventional single-junction, silicon or GaAs solar cells. The cells for STARSHINE-3 are 24% efficient under air mass zero (AM0). This compares compares favorably to silicon solar cells that are 16% efficient or GaAs cells at 20% efficiency.
• STARSHINE-3 employs also a lithium-ion battery for energy storage consisting of three Sony 18650 cells. The nominal rating is 4.2 V at 1.5 Ah per cell, connected in series.
• A third power related experiment on STARSHINE-3 is testing optically clear silicone rubber as a potential material for fabricating solar concentrator lenses.
1) R. G. Moore, J. Lean, J. M. Picone, S. Knowles, A. Hedin, J. Emmert, “Upper Atmosphere Densities Derived from Starshine Spacecraft Orbits,” Proceedings of AIAA/USU Conference on Small Satellites, Logan, UT, Aug. 11-14, 2003, SSC03-V-2
2) G. Moore, W. Braun, P. Jenkins, W. Holemans, D. Lefevre, M. Batchelder, “STARSHINE Missions in 2001,” AIAA/USU Conference on Small Satellites, Logan UT, Aug. 13-16, 2001, SSC01-IV-6
3) B. Braun, C. Butkiewicz, J. Vasquez, G. Moore, “The Starshine Satellite From Concept to Delivery in Four Months,” Proceedings of the 13th Annual AIAA/USU Conference on Small Satellites, Aug. 23-26, 1999, Logan UT, SSC99-I-7
5) Information provided by Gil Moore, Director of the STARSHINE project
8) “Space Sciences: The Navy & Satellites - Starshine 2,” URL: http://www.onr.navy.mil/focus/spacesciences/satellites/starshine2.htm
9) “Astronauts deploy satellite to be tracked by students,” Spaceflight Now, Dec. 16, 2001, URL: http://spaceflightnow.com/station/stage8a/011216starshine/
10) “Starshine 2 return - A glittering satellite named Starshine 2 will disintegrate in Earth's atmosphere on April 26, 2002,” NASA Science News, April 25, 2002, URL: http://science.nasa.gov/science-news/science-at-nasa/2002/25apr_starshine2/
12) “A Disco Ball in Space,” NASA, Oct. 9, 2001, URL: http://science.nasa.gov/science-news/science-at-nasa/2001/ast09oct_1/
14) P. Jenkins, D. Scheiman, D. Wilt, R. Raffaelle, R. Button. T. Kerslake, M. Batchelder, D. Lefevre, R. G. Moore, “Results from the Advance Power Technology Experiment on the Starshine-3 Satellite,” Proceedings of the AIAA/USU Conference on Small Satellites, Logan, UT, Aug. 12-15, 2002, SSC02-X-3
15) Phillip Jenkins, David Scheiman, David Wilt, Ryne Raffaelle, Robert Button, Mark Smith,Thomas Kerslake, Thomas Miller, “Advance Power Technology Demonstration on Starshine-3,”NASA/C_2002-211831, URL: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030000604_2002154741.pdf
16) Phillip Jenkins, David Scheiman, David Wilt, Ryne Raffaelle, Robert Button, Mark Smith,Thomas Kerslake, Thomas Miller, “Advance Power Technology Experiment for the Starshine 3 Satellite,” AIAA/USU Conference on Small Satellites, Logan UT, Aug. 13-16, 2001, SSC01-VI-8
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.