RADFXSAT (FOX-1B)

RADFXSAT, also catalogued under its amateur radio designation Fox-1B and assigned the NORAD catalog ID 43017, is an American amateur radio satellite launched in November 2017. Operating under the international designator 2017-073E, the spacecraft represents a collaboration between Vanderbilt University, which serves as the mission operator, and the Radio Amateur Satellite Corporation of North America (AMSAT-NA), which designed and built the hardware. As a 1U CubeSat with a mass of approximately 1 kilogram, RADFXSAT is a compact yet capable platform that supports both amateur radio communication and university-led scientific work. The satellite remains in orbit as of the time of this writing.

Mission and Purpose

RADFXSAT's dual identity — operating simultaneously under the AMSAT designation Fox-1B and the Vanderbilt University mission name RADFXSAT — reflects the collaborative nature of the spacecraft and the two distinct communities it serves.

On the amateur radio side, the satellite is the second member of AMSAT-NA's Fox series, a family of small CubeSats designed to provide accessible FM voice transponder capability to licensed amateur radio operators around the world. Fox-1B carries a single-channel FM repeater, allowing radio amateurs to use the satellite as an in-orbit relay station, making contact across distances that would otherwise be impossible with line-of-sight terrestrial equipment. The uplink frequencies operate in the 70-centimeter and 23-centimeter bands, while the downlink uses the 2-meter band — a configuration that allows a wide range of amateur radio equipment to access the bird. In the amateur satellite community, the spacecraft was designated AMSAT OSCAR 91 (AO-91), continuing the long-running OSCAR numbering tradition that traces its roots back to the earliest days of amateur spaceflight in the 1960s.

On the scientific side, Vanderbilt University's involvement introduces a radiation-focused research dimension that gives the satellite its primary mission name: RADFXSAT stands for Radiation Effects Satellite. Vanderbilt has a well-established research program in the study of how ionizing radiation affects electronic components and systems — work with direct implications for the reliability and longevity of satellites, spacecraft, and other systems that must operate in the harsh radiation environment of space. By flying experimental electronics aboard a functioning CubeSat in low Earth orbit, Vanderbilt researchers can gather real-world data on radiation effects under actual space conditions, complementing laboratory-based testing. The specific parameters and findings of the Vanderbilt radiation experiment are not documented in the public catalog data available at the time of this article.

Though the mission type and current operational status are not confirmed in catalog records, the satellite's design — combining an operational amateur radio payload with a scientific instrument suite — exemplifies the kind of cost-effective, multi-purpose small satellite architecture that has become increasingly common in the CubeSat era.

Orbit and Tracking

RADFXSAT occupies a sun-synchronous orbit (SSO), a type of nearly polar orbit in which the satellite's orbital plane precesses at a rate that keeps it roughly synchronized with the Earth's rotation around the Sun. The practical result is that the satellite passes over any given point on Earth at approximately the same local solar time on each pass. Sun-synchronous orbits are widely used for Earth observation and remote sensing missions because they provide consistent lighting conditions from pass to pass, but they are also useful for small scientific payloads because the predictable geometry aids in data interpretation.

The spacecraft's current orbital parameters place its apogee at 638 kilometers and its perigee at 428 kilometers, producing a moderately elliptical orbit at an inclination of 97.5 degrees to the equatorial plane. This inclination, slightly beyond 90 degrees, is characteristic of sun-synchronous orbits and gives the satellite near-global coverage over the course of a day, passing over both polar regions. With an orbital period of approximately 95.2 minutes, RADFXSAT completes roughly fifteen orbits per day, meaning that a ground station at mid-latitudes can expect several usable passes in a twenty-four-hour period.

The difference between the apogee and perigee — roughly 210 kilometers — means that the satellite's altitude varies meaningfully along each orbit, a factor that is relevant both for amateur radio operators planning contacts and for radiation researchers monitoring the varying flux of energetic particles as the spacecraft moves through different regions of the inner radiation environment. The orbit has not decayed to the point of reentry; the satellite remains in orbit.

For tracking purposes, RADFXSAT is monitored and catalogued by United States Space Command under NORAD ID 43017. Real-time and predictive tracking data are available through services including those provided by this site, using publicly available two-line element sets (TLEs) regularly updated as the orbit evolves over time.

Design and Operator

RADFXSAT was designed and manufactured by AMSAT-NA, the Radio Amateur Satellite Corporation of North America, a nonprofit volunteer organization with a decades-long history of building and operating amateur satellites. AMSAT-NA developed the Fox-series CubeSat bus specifically to provide a low-cost, standardized platform capable of carrying both an FM transponder and secondary experimental payloads. The Fox bus is a 1U CubeSat form factor, meaning the entire spacecraft fits within a 10 × 10 × 10 centimeter envelope and has a mass of approximately 1 kilogram — constraints that impose strict limits on power, volume, and mass but that also allow the satellite to be launched as a secondary payload at relatively low cost.

The antenna configuration reflects the dual-band nature of amateur satellite operations. A whip antenna handles the 70-centimeter and 23-centimeter uplink bands, while a separate antenna manages the 2-meter downlink. This arrangement allows the onboard FM transponder to receive signals from operators on the ground, process them, and retransmit them at the downlink frequency — effectively functioning as an orbiting repeater accessible to any amateur radio operator with appropriate equipment and a clear view of the sky.

Vanderbilt University, based in Nashville, Tennessee, holds the operational authority for the satellite and is the designated operator in international satellite registry records. The university's role distinguishes RADFXSAT from its Fox-series sibling Fox-1A, where AMSAT-NA itself was the primary operator. This arrangement reflects a broader trend in which universities partner with experienced smallsat developers to fly scientific payloads on amateur radio platforms, leveraging existing infrastructure and regulatory frameworks to reduce mission cost and complexity.

Launch and Current Status

RADFXSAT lifted off on November 17, 2017, as part of a rideshare mission that placed the small spacecraft into its sun-synchronous orbit. The launch gave the satellite its international designator of 2017-073E, indicating it was the fifth catalogued object from the seventy-third launch of 2017.

The satellite's specific operational status — whether the amateur radio transponder remains active, whether the Vanderbilt radiation experiment returned data, and how long either system functioned nominally — is not confirmed in the publicly available catalog record at the time of writing. Small satellites in low Earth orbit, particularly 1U CubeSats, face significant engineering challenges related to power management, thermal cycling, and radiation-induced component degradation. The radiation environment that RADFXSAT was partially designed to study is also, inevitably, a factor in the long-term health of the spacecraft itself.

Significance and Legacy

RADFXSAT occupies a meaningful niche in the history of small satellite development. As the second Fox-series satellite, it helped AMSAT-NA validate and refine the Fox CubeSat bus architecture, which the organization has continued to develop through subsequent missions. The Fox series as a whole demonstrated that a small volunteer-driven organization could deliver reliable FM transponder capability on a CubeSat budget, keeping amateur satellite communication accessible to operators without specialized or expensive ground equipment.

The Vanderbilt partnership also illustrates an increasingly common model in the small satellite industry: the use of amateur radio satellites as platforms for scientific payloads, where regulatory approval, launch heritage, and operational expertise already exist within the amateur community. This model allows universities and research institutions to access real space environments for experimental validation at a fraction of the cost of a dedicated scientific mission, while the host satellite organization benefits from the additional funding and visibility that a university partner brings.

At a mass of just 1 kilogram and occupying one of the smallest standard form factors available, RADFXSAT represents an economy of design that has become a defining characteristic of the CubeSat era. The satellite's orbit, combining a sun-synchronous geometry with altitudes between 428 and 638 kilometers, positions it well for the kind of long-duration low Earth orbit science that Vanderbilt's radiation effects research requires, while simultaneously delivering the global, predictable coverage that makes an amateur radio repeater satellite useful to operators across many countries and time zones.