HODOYOSHI-4

HODOYOSHI-4 is a Japanese micro-satellite operated by the Japan Aerospace Exploration Agency (JAXA) and catalogued by the United States Space Surveillance Network under NORAD ID 40011. It was launched on June 18, 2014, and is internationally designated 2014-033B. As of the most recent orbital data, the spacecraft remains operational in a sun-synchronous orbit, continuing a mission whose precise objectives are not fully disclosed in public catalogs. The satellite represents an important example of Japan's efforts to develop compact, capable small spacecraft during a period of rapid evolution in the global microsatellite sector.

Mission and Purpose

HODOYOSHI-4 was developed under Japan's Funding Program for World-Leading Innovative Research and Development on Science and Technology, a national initiative designed to push the boundaries of emerging technologies by channeling government resources into high-risk, high-reward research projects. Within this framework, the Hodoyoshi program was conceived as a demonstration of what small, relatively low-cost satellites could accomplish when engineered with care and ambition. The name "Hodoyoshi" itself can be translated roughly as "good enough," a philosophy that challenges the conventional satellite-building paradigm of over-engineering systems at great expense, instead asking how much mission value can be extracted from a compact, pragmatic design.

While the specific mission type for HODOYOSHI-4 is not publicly documented in the standard tracking catalogs, the satellite belongs to a program that broadly explored Earth observation, technology demonstration, and the advancement of miniaturized spacecraft components. The Hodoyoshi series sought to prove that microsatellites could fill roles previously reserved for much larger, costlier platforms, reducing barriers to space access for research institutions and smaller spacefaring nations. HODOYOSHI-4 was part of a paired effort alongside its companion HODOYOSHI-3 (2014-033A), both sharing the same launch opportunity to maximize the efficiency of deployment costs.

One of the most technically notable aspects of the satellite is the integration of a miniature ion thruster for orbital maintenance. Ion propulsion systems offer significantly higher specific impulse than conventional chemical thrusters — in HODOYOSHI-4's case, a specific impulse of approximately 1,100 seconds — meaning the propellant is used far more efficiently to generate thrust. This allows a very small amount of propellant to sustain orbital altitude over extended periods. The thruster operates at around 20 watts of power, making it well matched to the modest but carefully managed power budget of the spacecraft. Demonstrating that ion propulsion could be meaningfully miniaturized and integrated into a bus of this size was a significant engineering milestone for Japanese small-satellite development.

Orbit and Tracking

HODOYOSHI-4 occupies a sun-synchronous orbit (SSO), a type of near-polar orbit in which the satellite's orbital plane precesses at a rate that keeps it roughly synchronized with the angle of the Sun relative to Earth's surface throughout the year. This characteristic is particularly valuable for Earth observation missions, as it ensures that the satellite passes over any given location at approximately the same local solar time on each revisit, providing consistent lighting conditions for imaging or sensing instruments. Sun-synchronous orbits are a standard choice for remote sensing and reconnaissance payloads precisely because of this repeatability.

The satellite's current orbital parameters place its apogee at approximately 625 kilometers and its perigee at approximately 591 kilometers above Earth's surface, giving it a relatively circular low Earth orbit with an eccentricity close to zero. The orbital inclination is 97.5 degrees, which is characteristic of sun-synchronous trajectories — slightly retrograde with respect to Earth's rotation, which is what enables the solar-synchronous precession. Each orbit takes approximately 96.7 minutes to complete, meaning the satellite circles the planet roughly 14 to 15 times per day.

Because its perigee remains well above the denser layers of the upper atmosphere, HODOYOSHI-4 experiences relatively modest atmospheric drag, contributing to its continued orbital longevity. The presence of the onboard ion thruster further aids in counteracting the slow orbital decay that affects all low Earth orbit spacecraft over time. As of the catalog data reflected here, the satellite has not re-entered the atmosphere and remains an active tracked object.

Observers and researchers can track HODOYOSHI-4 using its NORAD ID 40011 or its COSPAR designator 2014-033B. Two-line element (TLE) sets distributed by space surveillance agencies provide the data needed to compute precise position and visibility predictions for any ground location.

Design and Operator

HODOYOSHI-4 is built around a compact box-shaped bus measuring approximately 0.5 by 0.6 by 0.7 meters — small enough to fit comfortably within the volume constraints of a secondary or piggyback launch configuration. This form factor was a deliberate design choice, allowing the satellite to share a rocket with a primary payload and thereby dramatically reducing the cost of getting to orbit. Piggyback launches are a common strategy for microsatellite operators, and designing the bus to accommodate this approach from the outset required careful attention to structural robustness and interface compatibility with launch vehicles.

Electrical power is generated by solar cells covering the surface of the spacecraft body itself, supplemented by two small deployable wing-like solar panels. The total estimated power generation capacity is on the order of 50 watts — a modest budget that nonetheless supports the satellite's payload and subsystems, including the ion thruster, onboard computers, communications systems, and any science or imaging instruments. Designing a functional spacecraft within such a constrained power envelope requires careful prioritization and efficient engineering across all subsystems.

The satellite was operated by JAXA, Japan's national space agency, which was established in 2003 through a merger of three predecessor Japanese space research organizations. JAXA has a broad mandate encompassing launch vehicle development, human spaceflight, deep space exploration, and Earth observation, and it has been an active participant in the global trend toward smaller, lower-cost satellite platforms. The Hodoyoshi program was closely associated with the University of Tokyo and the broader academic-industrial research network that JAXA facilitates.

The manufacturer of HODOYOSHI-4 is not recorded in publicly available tracking catalogs. The satellite is registered to Japan as its owner country.

Significance and Current Status

HODOYOSHI-4 occupies a meaningful place in the history of Japanese small satellite development. The Hodoyoshi program emerged at a time when the global satellite industry was undergoing a fundamental shift, with CubeSats and microsatellites beginning to challenge the assumption that serious space science and applications required large, expensive spacecraft. Japan, with its strong tradition in precision engineering and space technology, was well positioned to contribute to this transformation, and the Hodoyoshi satellites were one of the country's most direct engagements with the new paradigm.

The successful in-orbit demonstration of a miniaturized ion thruster was particularly consequential. Propulsion capability is one of the key features that distinguishes capable microsatellites from simpler, passive payloads — it enables operators to maintain orbits, perform collision avoidance maneuvers, and potentially change orbital parameters. Proving that this technology could be packaged within the constraints of a small bus opened the door to more ambitious future microsatellite missions with active orbital management.

The satellite was also a product of Japan's commitment to funding frontier research through structured national programs, illustrating how government investment in early-stage technology development can translate into tangible hardware that reaches orbit. This model of research-driven satellite development continues to influence how Japan and other spacefaring nations approach the challenge of building and deploying new generations of small satellites.

HODOYOSHI-4 remains in orbit as of the most recent available data. The current operational status of its instruments and subsystems is not documented in public catalogs, and whether it continues to transmit data or has concluded its active mission phase is not definitively established in open sources.

How to Spot It

HODOYOSHI-4 is a small microsatellite with a compact body and limited surface area, and it does not carry large reflective structures such as those found on communications satellites or the International Space Station. As a result, it is not among the most prominently visible objects in low Earth orbit and would not typically appear as a bright naked-eye object under ordinary conditions.

That said, any spacecraft in a low Earth orbit at altitudes between 591 and 625 kilometers can in principle be observed from the ground during twilight periods, when the satellite is illuminated by sunlight while the observer's sky is dark enough to see it. With optical aid and precise tracking predictions generated from current TLE data using its NORAD ID 40011, dedicated observers may be able to locate and follow the satellite as it crosses the sky. Its orbital period of 96.7 minutes and sun-synchronous inclination of 97.5 degrees mean that it passes over most populated latitudes regularly, making it accessible to observers across a wide geographic range on favorable passes.