A History of Small Satellites

What Makes a Satellite “Small”?

Small satellites represent a significant and rapidly growing segment of space technology. Their classification is primarily based on mass, though size is also a factor. These compact spacecraft range from the size of a large kitchen fridge down to devices that can be held in one’s hand. The general threshold for a small satellite, or “smallsat,” is a mass below 500 kg (1100 lb). Within this broad category, there are several distinct classifications:

• Minisatellite: These typically weigh between 100 and 180 kilograms (kg) according to NASA, although some industry definitions extend this up to 500 kg. Minisatellites are versatile and can be mass-produced for constellation-based systems. Common applications include commercial remote sensing, messaging services like Orbcomm, large telecommunications constellations such as OneWeb and Starlink, and meteorological observations.
• Microsatellite: Generally falling in the 10 to 100 kg range, microsatellites support scientific research and messaging applications. They are particularly beneficial in multi-satellite systems due to their ability to provide frequent revisits over an area of interest.
• Nanosatellite: With a mass between 1 and 10 kg, this category is famously associated with the CubeSat standard.
  • CubeSats: These are a specific class of nanosatellites that adhere to a standardized unit size known as “1U.” A 1U CubeSat measures 10x10x10 centimeters and typically weighs around 1.33 kg. This modular design can be scaled to larger configurations such as 1.5U, 2U, 3U, 6U, and even 12U.
• Picosatellite: These tiny satellites range from 0.01 to 1 kg (10 grams to 1 kg). They are often used for data interchange over internet networks or operate in cooperative formations, sometimes alongside a larger “mother” spacecraft.
• Femtosatellite: This is the smallest category, with a mass between 0.001 and 0.01 kg (1 to 10 grams). Femtosatellites, often leveraging cutting-edge nanotechnology, may accompany larger spacecraft as operational signal partners or for highly specialized, minimal-mass experiments.

The development of the CubeSat standard, in particular, has been a significant catalyst in the small satellite arena. Before CubeSats, satellite development was often a bespoke, expensive, and lengthy process, largely confining it to major government agencies and large corporations. The introduction of a standardized form factor simplified design and manufacturing. This, in turn, fostered the growth of an ecosystem providing off-the-shelf components, which dramatically reduced design complexity and cost. Furthermore, standardization streamlined the launch integration process, frequently allowing CubeSats to “hitch a ride” as secondary payloads on rockets carrying larger satellites, which further lowered the financial barrier to space access. The consequence was a surge in participation from universities, startups, and smaller organizations, which cultivated a new wave of innovation and trained a new generation of space engineers. This ripple effect extended far beyond merely defining a smaller size for satellites; it fundamentally changed who could participate in space activities and how quickly new ideas could be tested in orbit.

Interestingly, while miniaturization has been a driving force, the definition of “smallsat” itself shows some evolution, particularly in industry analyses where the upper mass limit is sometimes extended to 1,200 kg. This reflects how increasingly capable satellites are being developed. Initially, the “small” designation was often a consequence of the restricted lifting power of early launch vehicles. As electronic components shrank and became more powerful, greater capabilities could be integrated into smaller volumes and masses. However, for demanding applications like large-scale telecommunication constellations (e.g., Starlink v2-mini at approximately 800 kg, or Iridium NEXT at around 860 kg), operators are constructing satellites that, while larger than traditional CubeSats or microsatellites, still embrace the philosophies of mass production and constellation deployment that were pioneered by smaller craft. This suggests that “small” is becoming as much about a design and operational philosophy – emphasizing agility, scalability, and cost-effectiveness relative to traditional monolithic satellites – as it is about absolute minimal size. Even as individual units grow to meet performance demands, the underlying principles of the smallsat approach continue to influence their development.

Table 1: Small Satellite Classifications

Mass ranges and dimensions can vary slightly by defining agency/source. LEO: Low Earth Orbit, MEO: Medium Earth Orbit, GEO: Geostationary Orbit, HEO: High Earth Orbit.

The Dawn of the Space Age: The First Small Satellites (1950s – 1960s)

The era of artificial satellites began with spacecraft that, by contemporary standards, were relatively small. These pioneering missions were monumental achievements, sparking the Space Race and opening new frontiers for science and technology. The very first satellites were “small” not by deliberate design to minimize size, but rather because the launch vehicles of the time had limited capacity. Despite this, their impact was immense.

Sputnik 1: The Beachball that Orbited the World

History changed on October 4, 1957, when the Soviet Union successfully launched Sputnik 1, the world’s first artificial satellite. It was a polished metal sphere, 58 centimeters (22.8 inches) in diameter, and weighed 83.6 kg (183.9 pounds). By today’s classifications, its mass would place it in the microsatellite category. Sputnik 1 circled the Earth approximately every 98 minutes, transmitting simple radio “beeps” that were picked up by scientists and amateur radio operators worldwide. These signals continued for about three weeks until its batteries expired on October 26, 1957. The launch of Sputnik 1 was a stunning technological accomplishment that caught the world, particularly the United States, off guard. It had significant political, military, technological, and scientific repercussions, effectively heralding the start of the space age.

The United States Responds: Explorer 1 and Vanguard 1

The United States quickly moved to launch its own satellites. On January 31, 1958, Explorer 1 successfully reached orbit, becoming America’s first satellite. Considerably smaller and lighter than Sputnik 1, Explorer 1 weighed 13.91 kg (30.66 pounds), classifying it as a microsatellite. It carried a scientific payload that led to a major discovery: the existence of the Van Allen radiation belts, zones of charged particles trapped by Earth’s magnetic field.

Just a few months later, on March 17, 1958, the U.S. Navy launched Vanguard 1. This satellite was even more diminutive, a mere 1.47 kg (3.25 pounds) sphere with a diameter of only 16.5 cm (about 6 inches). Its small size led Soviet Premier Nikita Khrushchev to famously refer to it as “the grapefruit satellite”. Vanguard 1 was a technological marvel for its time; it was the first satellite to successfully use solar cells to power its transmitter. This solar-powered transmitter continued to operate until May 1964. Though communication ceased then, Vanguard 1 remains in orbit, making it the oldest artificial object still circling the Earth. Its symmetrical shape and small size also proved useful for scientists studying the Earth’s upper atmosphere, as its orbital changes helped determine atmospheric densities. These early missions demonstrated that immense scientific value and technological firsts could be achieved with relatively small spacecraft.

Early Innovators: Weather Watchers and Amateur Signals

Beyond the initial race to simply achieve orbit and conduct fundamental science, practical applications for satellites emerged quickly. NASA launched TIROS-1 (Television Infrared Observation Satellite) on April 1, 1960. Weighing around 122 kg (placing it at the upper end of microsatellites or the lower end of minisatellites), TIROS-1 became the world’s first successful weather satellite. It transmitted infrared images of Earth’s cloud cover and demonstrated the ability to detect and chart hurricanes from space, revolutionizing meteorology. This early success in a civilian application was vital for building broader support for space technology, showcasing its potential to deliver tangible benefits beyond geopolitical competition or pure scientific inquiry.

The 1960s also saw the launch of OSCAR 1 (Orbiting Satellite Carrying Amateur Radio) on December 12, 1961. This 10 kg satellite, fitting the nanosatellite or light microsatellite class, was a trailblazer. It was the world’s first non-governmental satellite, built by a group of amateur radio enthusiasts in California for a remarkably low cost of about $63. Launched as a secondary payload, OSCAR 1 transmitted a simple “HI-HI” Morse code message for nearly 20 days. This signal was detected by thousands of radio operators in 28 countries, demonstrating the potential for citizen involvement in space activities. OSCAR 1’s success was a very early indication of the potential for broader, non-governmental participation in space, a theme that would see a dramatic resurgence with the advent of CubeSats decades later. It subtly challenged the notion that space was exclusively for superpowers and their vast resources, planting an early seed for the democratization of space.

Table 2: Key Early Small Satellites (1957-1960s)

Expanding Capabilities and New Horizons (1970s – 1980s)

Following the foundational breakthroughs of the late 1950s and 1960s, the subsequent two decades saw small satellites continue to evolve, carving out niches in scientific exploration and demonstrating the potential for academic institutions to become key players in space technology. Dedicated programs also began to emerge, recognizing the unique value of smaller, focused missions.

Small Satellites in Scientific Exploration

NASA’s Explorer program, which had a storied beginning with Explorer 1, remained a vital avenue for space science. Throughout the 1970s and 1980s, numerous small spacecraft were launched under this program, conducting investigations into Earth science, astronomy, and the physics of the Sun and its interaction with Earth (heliophysics). These satellites, though often small in size and complexity compared to larger flagship missions, were generally well-engineered and highly reliable. Many operated for five years or more, with the longest-lived, IMP-8 (Interplanetary Monitoring Platform 8), functioning for an impressive 33 years.

Even within the monumental Apollo program, focused on human lunar exploration, small satellites found a role. The Apollo 15 mission in 1971 and Apollo 16 in 1972 each deployed a small sub-satellite into lunar orbit. Known as the Particles and Fields Subsatellites (PFS-1 and PFS-2 respectively), these spacecraft each weighed around 36 kg. Their purpose was to study the lunar environment, including its tenuous atmosphere, magnetic field, and the distribution of charged particles around the Moon, long after the astronauts had returned to Earth. This demonstrated that small, dedicated scientific platforms could effectively complement even the most ambitious human spaceflight endeavors, gathering valuable contextual data in unique environments. The versatility shown by the continued Explorer missions and the Apollo sub-satellites established small spacecraft not merely as introductory projects but as legitimate and cost-effective tools for a diverse array of scientific disciplines.

University Pioneers: The UoSAT Missions

A significant development during this period was the emergence of universities as centers for small satellite innovation. The University of Surrey in the United Kingdom, under the leadership of Martin Sweeting, became a prominent early example.

Their first major success was UoSAT-1 (University of Surrey Satellite 1), later designated UoSAT-OSCAR 9. Launched on October 6, 1981, this 52 kg microsatellite was a landmark achievement. It was designed and built by a small team of research scientists and students, demonstrating that sophisticated small satellites could be developed and launched relatively quickly (within 30 months) and on a remarkably modest budget (around £250,000 at the time). UoSAT-1 was packed with innovative features for its size, including in-orbit re-programmable computers, a CCD (charge-coupled device) camera for Earth imaging, and a Digitalker speech synthesizer. Its signals were received and analyzed by thousands of amateur radio enthusiasts, schools, and universities around the world, fostering education and engagement. UoSAT-1 far exceeded its anticipated two-year orbital lifespan, remaining operational for over eight years before re-entering the atmosphere in October 1989.

Building on this success, UoSAT-2 was launched on March 1, 1984. This 60 kg microsatellite was constructed in an even shorter timeframe – just six months. It carried the first operational digital Store-and-Forward communications payload, allowing messages to be uploaded to the satellite, stored, and then downloaded by users elsewhere on Earth. It also featured an improved CCD camera and experiments to evaluate new technologies and study the effects of the space radiation environment on electronic components. UoSAT-2 played a notable role in supporting the 1988 Soviet-Canadian “SkiTrek” transpolar expedition, relaying the skiers’ latest known position via its voice synthesizer to a global audience of listeners. The UoSAT missions were pivotal because they showcased that academic institutions could spearhead the development of advanced small satellites with practical applications, operating on timelines and budgets that were orders of magnitude smaller than traditional space programs. This fostered a low-cost, rapid-development approach and provided a model for other universities, effectively incubating talent and new ideas for the growing smallsat field. This academic involvement was a important precursor to the widespread university participation that would later characterize the CubeSat era.

Laying Groundwork: Early Programmatic Support

The value of smaller, scientifically focused missions gained formal recognition from major space agencies. In 1989, NASA initiated the Small Explorer Program (SMEX) as a successor to the original Explorer program. The SMEX program was designed to utilize small spacecraft for missions in astrophysics, space physics, and upper atmospheric science, with defined cost caps (around $120 million in fiscal year 2017 dollars). An important secondary objective of SMEX was to nurture a new generation of engineers by providing hands-on experience in spacecraft development. This institutional backing was significant because while individual small satellite projects had demonstrated promise, dedicated funding and programmatic structures are essential for sustained development and regular access to space. The SMEX program provided this framework, helping to legitimize and stabilize the field, moving it beyond ad-hoc projects and paving the way for a more systematic utilization of small satellites for scientific research.

While not a small satellite itself, the Solar Maximum Mission (“SolarMax”), launched in February 1980, became notable for its successful in-orbit repair by the crew of the Space Shuttle Challenger in 1984. This event highlighted the emerging capabilities for interacting with and servicing satellites in orbit, a concept that could indirectly enhance the longevity and utility of various classes of spacecraft.

Miniaturization Takes Hold: The Transformative 1990s

The 1990s ushered in an era of significant change for small satellites, largely propelled by the relentless pace of advancements in electronics and an increasing demand for more affordable access to space. This decade was important, establishing the technological and conceptual foundations for the small satellite boom that would characterize the 21st century.

The Shrinking World of Satellite Components

The miniaturization trend that revolutionized consumer electronics, such as personal computers and mobile phones, began to exert a powerful influence on satellite design. Processors, memory chips, sensors, and communication systems became progressively smaller, lighter, and more power-efficient. This meant that significant operational capabilities could be packed into much smaller satellite packages. The reduction in physical size and mass had a cascading effect: it led to lower development costs, shorter assembly times, and, critically, reduced launch costs. Smaller satellites could more easily share rides on rockets carrying larger primary payloads or utilize newly emerging smaller, dedicated launch vehicles. Nanotechnology also began to be explored as a means to further decrease component size without sacrificing operational efficiency. This progress in component technology was a fundamental enabler, making the very idea of highly capable, very small satellites physically achievable.

New Ways to Orbit: The Pegasus Air-Launched Rocket

Recognizing the growing market for small satellite launches, Orbital Sciences Corporation (now part of Northrop Grumman) introduced the Pegasus rocket. Its first successful launch occurred in 1990, marking the debut of the world’s first commercially developed, air-launched space booster. The Pegasus is carried aloft by a large carrier aircraft – initially a NASA B-52 bomber and later a modified L-1011 “Stargazer” airliner – to an altitude of approximately 12,000 meters (around 39,000 feet). Once released from the aircraft, the three-stage solid-fueled rocket ignites its engines and carries its payload, typically small satellites up to about 450 kg, into low Earth orbit.

This air-launch system offered several advantages over traditional ground-based launches, including increased flexibility in launch timing and inclination, as launches were not tied to specific, geographically limited launch sites. Pegasus was specifically tailored for the small satellite market, and several NASA missions, including some within the Small Explorer (SMEX) program like the Submillimeter Wave Astronomy Satellite (SWAS) in 1998 and the Wide-Field Infrared Explorer (WIRE) in 1999, utilized this launch vehicle. The commercial viability of a dedicated small launcher like Pegasus was a strong indicator that the small satellite sector was maturing and substantial enough to warrant its own specialized launch infrastructure. This, in turn, likely encouraged further investment and development in small satellite technology itself.

The Birth of a Standard: CubeSats Conceived (1999)

Perhaps the most far-reaching development of the decade for small satellites was conceptual. In 1999, Professor Jordi Puig-Suari of California Polytechnic State University (Cal Poly) and Professor Bob Twiggs of Stanford University collaborated to address a need for more accessible, hands-on space education. They envisioned a standardized, very small satellite form factor that would allow graduate students to design, build, test, and operate a complete spacecraft, mirroring the capabilities of early satellites like Sputnik, but at a fraction of the cost and effort.

They proposed a 10-centimeter cube, designated “1U,” as the basic unit for these “CubeSats.” This size was deemed sufficient to accommodate a basic communications payload, solar panels for power, and a battery. The core idea was that this simple, standardized design would dramatically reduce costs and development times, opening up space access to a much wider range of users, particularly within academia. While the first CubeSats would not launch until the following decade, the definition of this standard in 1999 was a pivotal moment, laying the groundwork for a revolution in how small satellites were built and utilized. The power of miniaturized components was undeniable, but it was this concept of standardization that promised to amplify those benefits exponentially, paving the way for mass production and the true democratization of space.

Notable Missions of the Decade

Surrey Satellite Technology Ltd. (SSTL), which spun out from the University of Surrey’s pioneering UoSAT program, continued its prolific output of microsatellites. Key missions from SSTL in the 1990s included:

• UoSAT-3 and UoSAT-4 (1990): UoSAT-3, a 50 kg satellite, carried a store-and-forward communications payload. UoSAT-4 encountered issues after launch.
• UoSAT-5 (1991): This 50 kg microsatellite featured enhanced store-and-forward communications and Earth imaging payloads, operating in the amateur satellite service.
• S80/T (1992): A 50 kg technology demonstration mission for CNES (the French space agency), designed to characterize the VHF radio environment in preparation for a proposed mobile communications system.
• PoSAT-1 (1993): Portugal’s first satellite, a 50 kg microsatellite for Earth observation and technology demonstration, carrying imagers and scientific experiments.
• HealthSat-2 (1993): A 44 kg communications satellite built for Satelife, USA, intended to support health information services in developing countries.
• CERISE (1995): A 50 kg French military reconnaissance satellite designed to intercept HF radio signals. In 1996, CERISE gained notoriety as the first verified case of an operational satellite being struck and damaged by a cataloged piece of space debris – a fragment from an Ariane rocket launched years earlier. This event was a stark, early warning of the growing risks in orbit, particularly for smaller satellites that might have less shielding.
• FASat-Alpha (1995) and FASat-Bravo (1998): These were 55 kg Earth observation microsatellites for the Chilean Air Force. FASat-Alpha failed to separate from the Ukrainian SICH-1 primary payload, leading to the construction and successful launch of FASat-Bravo.
• Clementine (1999): Not to be confused with NASA’s earlier lunar mission of the same name, this 50 kg satellite was built by Thales Alenia Space for the DGA (French armament procurement agency) for military communications intelligence, targeting low-frequency electronic signals.

Beyond SSTL’s work, NASA’s Stardust mission, launched in 1999, had a launch mass of 385 kg, placing it in the minisatellite category by some definitions. It embarked on a mission to collect comet dust samples and successfully returned them to Earth years later. Also, while NASA’s “Great Observatories” like the Hubble Space Telescope (launched in 1990) were massive spacecraft, the agency did deploy smaller systems for planetary exploration. The Mars Pathfinder mission, which landed on Mars in 1997 after a 1996 launch, included the Sojourner rover. Sojourner was a very small (10.6 kg) wheeled vehicle that successfully demonstrated micro-rover technology on the Martian surface.

The CubeSat Revolution and a New Century (2000 – 2009)

The dawn of the 21st century marked the practical realization of the CubeSat concept, transforming it from an academic blueprint into a widely adopted platform that began to reshape access to space. This decade was characterized by the first launches of these standardized nanosatellites. These early missions were primarily driven by educational objectives and technology demonstrations, but they critically laid the foundation for the diverse commercial and scientific applications that would follow.

The First CubeSats Take Flight

The CubeSat standard, formally defined in 1999 by Professors Jordi Puig-Suari and Bob Twiggs, saw its inaugural on-orbit deployment on June 30, 2003. A Russian Rokot launch vehicle carried a cluster of six CubeSats into orbit from Plesetsk Cosmodrome in Russia, a landmark event for the growing small satellite community. This first batch of CubeSats primarily originated from universities:

• AAU CubeSat (Aalborg University, Denmark): A 1U satellite developed by students. Its mission was technology demonstration, including an attempt at Earth imaging with a small camera. It remained operational for approximately 2.5 months before its battery depleted.
• CUTE-I (Tokyo Institute of Technology, Japan): This 1U satellite, also designated OSCAR 55 (Orbiting Satellite Carrying Amateur Radio), served the amateur radio community and proved to be remarkably long-lived, continuing to transmit housekeeping data for many years.
• XI-IV (University of Tokyo, Japan): Another 1U CubeSat (designated OSCAR 57) dedicated to amateur radio communications. Like CUTE-I, it demonstrated impressive longevity.
• CanX-1 (University of Toronto, Canada): A 1U technology demonstrator from which, unfortunately, no signals were received after launch.
• DTUsat (Technical University of Denmark): This 1U CubeSat was intended for tether deployment research, but no contact was established post-launch.
• QuakeSat (Stanford University/QuakeFinder LLC, USA): A somewhat larger 3U CubeSat (three 1U units stacked together). Its mission was to detect ultra-low frequency (ULF) electromagnetic signals that some researchers believe could be precursors to earthquakes. QuakeSat successfully completed its mission, gathering data for several years.

Following this pioneering launch, other university-led and research-focused CubeSats made their way to orbit. Notable examples include UWE-1 (University of Würzburg, Germany) launched in 2005 for technology testing, and GeneSat-1, a 3U CubeSat launched in December 2006 as a collaborative effort between NASA Ames Research Center and Santa Clara University. GeneSat-1 carried a miniaturized laboratory to study the effects of the space environment on microorganisms. The initial purpose of these CubeSats was overwhelmingly to serve as an educational platform, providing students and professional engineers with hands-on experience, and to demonstrate specific technologies in the harsh environment of space at a relatively low cost. The successful launch and operation of these first CubeSats, largely by university teams, was the tangible beginning of a significant broadening of access to space – the “democratization of space” was taking root.

Educational Tools and Technology Testbeds

The primary appeal and driver for early CubeSat missions was their immense utility in education and training. For universities worldwide, the CubeSat standard offered an unprecedented opportunity. Students could now gain invaluable hands-on experience encompassing the entire lifecycle of a space mission: from initial concept and design, through building and rigorous testing, to launch and on-orbit operations. This was a paradigm shift from purely theoretical studies or work on subsystems of much larger, institutionally led projects. The affordability and relatively short development cycle of CubeSats, compared to traditional satellites, made them an attractive option for academic programs.

Beyond their educational role, CubeSats quickly established themselves as ideal platforms for in-orbit testing and validation of new technologies and components. Experimental sensors, novel communication systems, new materials, or innovative deployment mechanisms could be flight-tested at a much lower cost and with a higher tolerance for risk than would be possible on larger, more expensive satellites. This led to the widespread adoption of a “fly-learn-re-fly” development philosophy, where lessons from one mission could be rapidly incorporated into the design of the next, accelerating the pace of innovation. While the CubeSat hardware standard itself significantly reduced costs and development timelines, the flight software (FSW) often remained a substantial undertaking for each mission. Unless code could be effectively reused, developing or heavily adapting FSW to control the satellite’s specific payload and achieve its unique objectives could consume considerable time and resources. This presented a challenge, somewhat offsetting the efficiencies gained from hardware standardization, and pointed towards a growing need for more modular, reusable, and perhaps open-source FSW solutions – a trend that would gain more traction in the years to follow.

Early Scientific and Commercial Adopters

While educational and technology demonstration missions dominated the CubeSat landscape in the 2000s, some early projects undertook focused scientific investigations. QuakeSat’s multi-year mission to search for electromagnetic earthquake precursors was a notable example of a science-driven CubeSat. The Aerospace Corporation also began its influential AeroCube series during this period; for instance, AeroCube-2 was launched in 2007. This series of small satellites, ranging from 0.5U to 3U, served to demonstrate innovative technologies such as miniature propulsion systems, advanced attitude determination and control devices, deorbit systems, and optical communications, as well as conducting scientific measurements like characterizing radiation levels in low Earth orbit.

The development and early successes of CubeSats began to incentivize the broader space industry to explore how a wider range of scientific objectives could be achieved at lower costs. The platform started to evolve beyond purely academic exercises, with its potential for more complex missions becoming increasingly apparent. These foundational academic and technology demonstration missions, by proving the viability and robustness of the CubeSat platform, were necessary precursors for the commercial CubeSat constellations that would emerge strongly in the following decade. Without this track record, commercial investment in CubeSat-based ventures would have been a far riskier proposition.

Table 3: Notable Early CubeSat Missions (2003-2009)

Status reflects information available from the period or shortly thereafter.

The SmallSat Boom: Constellations and Commerce (2010 – 2019)

The decade from 2010 to 2019 witnessed an unprecedented surge in the development and deployment of small satellites, particularly CubeSats. These compact spacecraft transitioned decisively from primarily academic tools and technology demonstrators to platforms for large-scale commercial operations and ambitious scientific missions. The rise of vast constellations for Earth observation and data services became a defining characteristic of this era, alongside the pioneering first steps of CubeSats venturing beyond the confines of Earth orbit.

Eyes on Earth: The Rise of Imaging Constellations

A new generation of companies emerged, leveraging the cost-effectiveness and scalability of small satellites to build extensive Earth-imaging constellations.

Planet Labs (now Planet), founded by former NASA scientists, began launching its “Dove” CubeSats in 2013, with Dove 1 and Dove 2 serving as initial demonstration units. Their “Flock” constellation, primarily composed of 3U CubeSats, grew at a remarkable pace. A landmark deployment occurred in February 2017, when 88 Dove satellites (Flock 3p) were launched on a single Indian PSLV rocket. This significantly contributed to Planet’s “Mission 1” objective: achieving near-daily multispectral imagery coverage of all Earth’s landmasses. Planet’s strategy centered on the mass production of these relatively inexpensive Doves, enabling frequent replenishment of the constellation and rapid incorporation of technological upgrades.

Skybox Imaging, which was later acquired by Google and then by Planet, took a slightly different approach. Skybox launched its first microsatellite, SkySat-1 (weighing around 83-110 kg), in November 2013. The SkySat satellites were larger and more expensive than the Doves but offered higher resolution imagery and the capability to capture full-motion video of targeted areas. Skybox’s plan involved utilizing “off-the-shelf” electronics to keep the cost of each satellite under US$50 million. The SkySat constellation expanded with subsequent launches, aiming to provide on-demand, high-resolution imagery and video services. The success of companies like Planet demonstrated a new paradigm in Earth observation: instead of relying on a few large, expensive, highly capable satellites providing infrequent views, they used a multitude of smaller, “good enough” sensors. This approach offered unprecedented temporal resolution – the ability to image locations much more frequently – which unlocked new applications like monitoring rapid environmental changes, near real-time tracking of assets, and building vast historical archives for trend analysis. Their often subscription-based business models made this wealth of data accessible to a far wider range of customers than ever before, disrupting the established satellite imagery market.

Listening In: Data and Communication Constellations

Beyond visual imaging, other companies built constellations to capture different types of data.

Spire Global began deploying its “Lemur” constellation of 3U CubeSats. The first LEMUR-1 was launched as a demonstration in 2014, with the first operational Lemur-2 satellites following soon after. Spire’s Lemur satellites are multi-purpose platforms, equipped with a suite of sensors for various applications:

• AIS (Automatic Identification System): For tracking maritime vessels globally.
• ADS-B (Automatic Dependent Surveillance–Broadcast): For tracking aircraft.
• GNSS Radio Occultation (GNSS-RO): This technique uses signals from Global Navigation Satellite Systems (like GPS) as they pass through Earth’s atmosphere. By measuring how these signals are bent and delayed, Spire can derive atmospheric data such as temperature, pressure, and humidity, which is valuable for weather forecasting and climate monitoring.
• Spire also utilizes reflected GNSS signals for remote sensing of Earth’s surface, including applications like soil moisture estimation and ocean wave characterization.By the end of the decade, Spire had launched nearly 100 Lemur nanosatellites, establishing one of the largest multi-purpose satellite constellations and providing diverse data streams to various industries.

CubeSats Go Interplanetary: The MarCO Mission

A truly groundbreaking achievement of this period was NASA’s Mars Cube One (MarCO) mission. This mission successfully sent two 6U CubeSats, named MarCO-A and MarCO-B (nicknamed “Wall-E” and “Eva”), to Mars. Launched in May 2018 along with NASA’s InSight lander, the two MarCO CubeSats flew independently to the Red Planet. Their primary objective was to provide real-time communications relay for the InSight lander during its critical entry, descent, and landing (EDL) sequence in November 2018. Both CubeSats successfully performed this function, relaying data back to Earth much faster than would have been possible otherwise.

The MarCO mission was the first time CubeSats had operated beyond Earth orbit, a significant proof-of-concept. It demonstrated that the low-cost, rapid-development philosophy inherent to CubeSats could be extended to the challenging environment of interplanetary space. This success opened the door for future small, focused interplanetary science missions, potentially as standalone probes or as valuable support elements for larger, more complex missions, significantly lowering the cost and increasing the cadence of solar system exploration. It fundamentally changed the perception of CubeSats from LEO-bound novelties to potentially serious tools for deep space endeavors.

Launch Access Diversifies: Rideshares and Dedicated Small Launchers

The exponential growth in the number of small satellites needing to reach orbit spurred significant developments in launch services.

Ridesharing, where multiple small satellites are launched as secondary payloads on rockets carrying a larger primary satellite, became increasingly common and sophisticated. The Indian Space Research Organisation’s (ISRO) Polar Satellite Launch Vehicle (PSLV) became a popular choice for such missions, memorably setting a world record in February 2017 by deploying 103 small satellites on a single flight.

The demand also fueled the development of dedicated small launch vehicles, rockets specifically designed to deliver small satellite payloads to orbit. These launchers offer customers more control over their launch schedule and orbital destination compared to rideshares. Rocket Lab’s Electron rocket was a prominent entrant in this market, achieving its first successful orbital launch in January 2018 and quickly establishing itself as a key provider for small satellite operators. The increased availability of diverse and more frequent launch opportunities was a critical enabler for the rapid growth of smallsat constellations and the overall small satellite market. This created a symbiotic relationship: the boom in small satellites created the market for these new launch services, and in turn, the enhanced accessibility and affordability of launch further fueled the smallsat industry’s expansion.

Market Growth and Technological Advancements

The number of smallsats launched annually saw a dramatic increase throughout the 2010s. Data indicates that between 2014 and 2023, smallsats (defined by BryceTech for later years as 1,200 kg and under, though generally smaller during this specific decade) accounted for 93% of all spacecraft launched. The “fly-learn-re-fly” approach, particularly prevalent in the CubeSat community, allowed for rapid iteration and improvement in satellite technology and mission design. Continuous advancements were made in further miniaturizing sensors, enhancing onboard processing capabilities, developing more efficient and compact power systems, and creating viable propulsion systems suitable for the mass and volume constraints of smallsats.

Modern Marvels and the Path to Tomorrow (2020 – 2025)

The early 2020s have seen the small satellite industry not only maintain but accelerate its rapid pace of innovation and deployment. Existing constellations are undergoing significant upgrades with enhanced capabilities, while new generations of small spacecraft are increasingly targeting lunar and deep space destinations. Onboard technologies such as artificial intelligence (AI), advanced propulsion systems, and inter-satellite links are becoming more sophisticated, making these compact platforms more autonomous and capable than ever before.

Continued Constellation Deployment and Upgrades

Major commercial constellations established in the previous decade continued to be replenished and technologically advanced. Planet’s fleet of “Dove” Earth-imaging CubeSats was upgraded to “SuperDoves” by August 2021, featuring more spectral bands for richer data collection. Their higher-resolution SkySat constellation was completed with the launch of its final three satellites in August 2020, bringing the total to 21.

Spire Global has been actively developing optical inter-satellite links (OISLs) for its LEMUR constellation of multi-purpose nanosatellites. In 2023, Spire successfully demonstrated a two-way laser communication link between two of its satellites in orbit, separated by distances up to 5,000 kilometers. This technology is a game-changer, promising significantly faster, more secure, and lower-latency data transmission by allowing satellites to communicate directly with each other, reducing reliance on ground station relays. Further launches incorporating OISL technology are planned for 2025.

The sheer number of small satellites launched remains high. In 2023, smallsats (defined in some analyses up to 1,200 kg) constituted 97% of all spacecraft launched and accounted for 63% of the total mass launched to orbit. A noticeable trend is that some next-generation satellites within these constellations are growing somewhat larger than their predecessors (e.g., Planet’s upcoming Pelican series compared to its SkySats, or SpaceX’s Starlink v2-mini satellites versus the original v1 design). This reflects a drive to pack even more capability – better sensors, more processing power, enhanced communication systems – into platforms that still benefit from the cost efficiencies of the smallsat manufacturing and deployment model.

Small Satellites Aim for the Moon and Beyond

The groundbreaking success of NASA’s MarCO CubeSats at Mars in 2018 emboldened the space community to plan and execute more ambitious small satellite missions beyond Earth orbit. The Moon, in particular, has become a key focus.

Commercial Lunar Payload Services (CLPS) program by NASA: This initiative is heavily reliant on commercial companies developing (relatively) small landers to deliver NASA science and technology payloads, as well as commercial cargo, to the lunar surface. These missions are pivotal in paving the way for a sustainable human presence on the Moon.

• Firefly Aerospace’s Blue Ghost Mission 1 lander successfully touched down in Mare Crisium on March 2, 2025, carrying a suite of NASA-sponsored experiments and commercial payloads.
• Intuitive Machines’ IM-2 lander (part of their Nova-C series) launched in late February 2025 and achieved a landing near the lunar south pole at Mons Mouton on March 6, 2025. Although the lander tipped onto its side after touchdown, similar to its predecessor IM-1, it was still able to achieve some of its mission objectives, demonstrating the resilience and iterative learning process in these commercial endeavors.These CLPS missions often act as delivery services for multiple even smaller payloads, such as miniature rovers and deployable instruments, showcasing a distributed and cost-effective approach to lunar exploration that is significantly enabled by small satellite technologies and philosophies. This model fosters competition and innovation, contributing to the development of a cislunar economy where small systems play foundational roles in reconnaissance, communication, and potentially resource prospecting.

Beyond government-sponsored programs, purely commercial ventures are also targeting celestial bodies:

• AstroForge’s Brokkr-2, a small satellite launched in February 2025, was designed to perform a flyby of a near-Earth asteroid to analyze its composition, with an eye towards future asteroid mining. Unfortunately, the mission encountered communication issues that prevented it from achieving its primary objective.Several other lunar missions involving small spacecraft are anticipated in 2025. For example, ispace’s Hakuto-R Mission 2 lunar lander is targeting a landing in Mare Frigoris in June 2025, and Blue Origin has announced plans for a “pathfinder” mission of its MK1 Lunar Lander during the year.

Smarter Satellites: Advancements in AI, Autonomy, and Advanced Sensors

A significant trend is the increasing integration of artificial intelligence (AI) and machine learning (ML) algorithms directly onto small satellites. This allows for sophisticated onboard data processing, autonomous operations (like self-tasking or fault detection and recovery), and enhanced decision-making capabilities. For example, a satellite might use AI to identify features of interest in the data it collects (e.g., detecting floods or wildfires in imagery) and then prioritize downlinking only the most relevant information, making more efficient use of limited communication bandwidth. This reduces the burden on ground control and allows for quicker data turnaround times.

Continued miniaturization and performance improvements in sensor technology mean that small satellites can now carry instruments capable of gathering more precise and diverse data across various parts of the electromagnetic spectrum. This includes advanced optical imagers, hyperspectral sensors, radar systems, and sophisticated radio frequency detectors. For instance, Ireland’s space sector is leveraging national expertise in areas like medical device manufacturing and photonics to develop advanced components for space applications, including AI-driven Earth observation technologies. The ESA Phi-Lab Ireland, a center for space research launched in May 2025 in collaboration with Irish Manufacturing Research and AMBER, specifically focuses on fostering such crossovers.

The combination of onboard AI for intelligent data processing and inter-satellite links for direct satellite-to-satellite communication is leading to “smarter” and more autonomous constellations. These systems are less dependent on ground infrastructure for tasking and data relay. OISLs, as demonstrated by Spire, create resilient networks in space, allowing data to be rapidly routed between satellites to an optimal downlink point or directly to other space-based assets. This reduces latency and increases the overall robustness of the constellation, effectively making the collective capability of the network greater than the sum of its individual satellite parts.

Propulsion and Inter-Satellite Links Get Smaller and Better

The development of compact, efficient, and reliable propulsion systems tailored for the unique mass, volume, and power constraints of small satellites remains a highly dynamic and important area of research and development. These propulsion systems are essential for a variety of functions, including precise orbit insertion and maintenance, constellation management (phasing and station-keeping), collision avoidance maneuvers, extending operational lifetimes, controlled deorbiting at end-of-life, and enabling interplanetary trajectories for missions beyond Earth orbit. A wide array of technologies are emerging and maturing, including various types of electric propulsion (ion thrusters, Hall effect thrusters), miniaturized chemical thrusters, cold gas systems, and more novel concepts like electrospray thrusters.

As noted, optical inter-satellite links are becoming a key enabling technology, particularly for large constellations. They offer the potential for very high bandwidth and low-latency communication directly between satellites, forming resilient mesh networks in space. This capability reduces the reliance on geographically distributed ground stations and can significantly speed up data delivery.

Noteworthy Missions and Technological Demonstrations in 2025

Beyond the major constellation deployments and lunar missions, numerous other small satellite activities continue to push the boundaries. NASA’s Technology Education Satellite 22 (TES-22), a tiny 1U CubeSat launched in January 2025, is conducting several experiments. A key payload is the “Exo-Brake,” a deployable drag sail designed to interact with the Earth’s upper atmosphere and significantly accelerate the satellite’s deorbiting process. This technology is vital for mitigating the growing problem of space debris by ensuring that small satellites can be removed from orbit promptly at the end of their operational lives. TES-22 also carries a radiation detector and a solid-state battery evaluation experiment, providing valuable data on the thermosphere and testing new power technologies.

The launch cadence for small satellites remains high, with companies like SpaceX (using its Falcon 9 rocket) and Rocket Lab (with its Electron vehicle) frequently lofting numerous smallsats into orbit. SpaceX’s dedicated rideshare missions, known as “Transporter” flights, which commenced in 2021, have become a particularly popular and cost-effective option for small satellite developers worldwide to gain access to space.

While getting to orbit has become significantly easier and more affordable for small satellites, the challenges are increasingly shifting towards effective and responsible operation in an ever-more crowded space environment. The proliferation of satellites, especially in popular low Earth orbits, raises serious concerns about space traffic management, radio frequency interference, and the long-term threat posed by space debris. Technologies like advanced propulsion for maneuverability and controlled deorbit (as demonstrated by TES-22’s Exo-Brake), coupled with improved space situational awareness, are becoming not just beneficial for individual mission success but essential for the overall health and sustainability of the orbital environment. The focus for the small satellite community is thus expanding from simply “can we launch it?” to “can we operate it effectively, safely, and responsibly throughout its entire lifecycle and ensure a sustainable future for space activities?”

Summary

The journey of small satellites, from the rudimentary yet revolutionary transmissions of Sputnik 1 to the intricate, interconnected orbital networks and interplanetary explorers of today, charts a remarkable trajectory of technological advancement and expanding ambition. What began as a consequence of early launch vehicle limitations quickly evolved into a field of deliberate innovation. Vanguard 1’s pioneering use of solar cells and Explorer 1’s discovery of the Van Allen belts underscored the immense potential residing in compact spacecraft. The dedicated efforts of university pioneers, exemplified by the UoSAT missions, were instrumental in demonstrating that access to space was not the exclusive domain of superpowers, thereby planting the seeds for much broader international and academic participation.

The 1990s proved to be a truly transformative decade. The relentless miniaturization of electronics, coupled with the visionary conception of the CubeSat standard, laid the critical groundwork for an explosion in small satellite development and deployment. As the 21st century dawned, this potential was vividly realized. The first CubeSats, initially serving as invaluable educational tools, rapidly matured into versatile platforms capable of conducting complex scientific research and forming the backbone of growing commercial constellations. Companies like Planet and Spire fundamentally redefined Earth observation and global data collection paradigms with their vast fleets of Dove and Lemur nanosatellites. In a landmark achievement, NASA’s MarCO mission extended the reach of CubeSats to Mars, proving their viability for interplanetary endeavors.

From 2020 through May 2025, this extraordinary momentum has not only continued but accelerated. Small satellites are now at the vanguard of a new era of lunar exploration, increasingly driven by commercial initiatives and international partnerships. The integration of onboard artificial intelligence, the development of advanced, miniaturized propulsion systems, and the advent of high-bandwidth inter-satellite communication links are endowing these spacecraft with unprecedented capabilities and autonomy.

The very success and proliferation of small satellites bring attendant challenges. The ease of access to orbit, while a triumph of engineering and economics, has intensified concerns regarding space debris, orbital crowding, and the long-term sustainable use of Earth’s orbital environment. Addressing these challenges is paramount for the future. Nevertheless, the ingenuity and dynamism characterizing the small satellite sector continue to unlock new possibilities for science, commerce, and our collective understanding of the cosmos. The ongoing evolution of these miniature marvels strongly indicates an ever-expanding and increasingly vital role in shaping humanity’s future activities and aspirations in space, consistently proving that great achievements can indeed emerge from small packages.