What Are Probes in Space: A Full Guide on How They Work

Space exploration has captivated humanity for decades.

Probes launched beyond Earth’s atmosphere have revealed astonishing discoveries about our solar system and universe.

This article will explain what are probes in space, how they work, and highlight some of the most groundbreaking missions.

What Are Probes in Space?

mars rover
Photo By NASA / JPL

Space probes are unmanned spacecraft designed to explore our solar system and beyond. They carry scientific instruments to collect data and transmit information back to Earth. Probes have visited every planet in our solar system. They have also journeyed to asteroids, comets, and even interstellar space. Probes expand our understanding of the cosmos and pave the way for future human spaceflight.

Brief History of Space Probes

Soviet Probe in Space
Photo By NASA Luna 2

The Soviet Union launched the first space probes in the late 1950s and early 1960s, including Luna 1, the first spacecraft to reach the vicinity of the Moon. The United States followed with Mariner 2, the first successful planetary flyby mission to Venus in 1962. Through the 1960s and 70s, probes like Venera 7 and Voyager 2 made historic first landings and flybys of other planets.

Over the past few decades, space agencies have actively launched increasingly advanced probes. For instance, NASA’s Galileo successfully orbited Jupiter, while the Cassini-Huygens mission delved deep into the mysteries of Saturn. Subsequently, the New Horizons probe achieved the first flyby of Pluto. Moreover, Mars has consistently been a prime target for probes in the quest for signs of life. As a result, crafts like the Curiosity and Perseverance rovers remain active and operational today.

Looking ahead, future probes are setting their sights even further. For example, NASA’s Parker Solar Probe is currently studying the Sun, and there’s palpable excitement for the upcoming Europa Clipper, which aims to investigate Jupiter’s moon, Europa. Ultimately, space probes have profoundly transformed our understanding of the solar system and the universe at large.

How Do Space Probes Work?

probe spacecraft
Photo By The Guardian

Space probes actively traverse our solar system and beyond as robotic explorers. Armed with scientific tools, they gather data and send it back to Earth.

Many probes rely on robust nuclear batteries for power, ensuring electricity supply for extended periods. They use thrusters to navigate through space. They also communicate with Earth through antennas and radio waves and capture detailed images with their cameras.

Heat shields play a vital role. For example, they protect probes assigned to study the intense heat of Venus. At the same time, precision navigation tools like gyroscopes and accelerometers keep probes on the right path.

Onboard computers run automated tasks and process data. When touching down on surfaces, probes use parachutes, retrorockets, inflatable airbags, or even sky-crane systems to ensure a smooth landing.

In the future, probes will leverage cutting-edge computer and power technologies, enabling them to journey to distant destinations like Jupiter’s oceanic moon, Europa. In summary, space probes have revealed incredible insights about our solar system.

Components of a Space Probe

gravity probe space craft
Photo By Standford

Space probes are intricate systems, and their various subsystems and components seamlessly collaborate to fulfill their exploration objectives. Let’s delve into the primary elements:

Power Source:

Firstly, every probe needs a power source to supply the electricity essential for its operations. Commonly, experts employ Radioisotope thermoelectric generators, which transform heat into energy.


Next, for movement and navigation through space, probes rely on thrusters and engines. The choices range from chemical rockets to ion engines and even solar sails.


To ensure the probe remains on its intended path, gyros, accelerometers, and sun sensors provide crucial data to the guidance system.


Then, for communication, large dish antennas and high-gain antenna arrays facilitate data transmission over vast distances, spanning millions of miles.


Central to the probe’s operations, the onboard computer executes the flight software and interprets commands dispatched from Earth.

Scientific Instruments:

Furthermore, to gather comprehensive data about a planet’s atmosphere, surface, magnetic fields, and more, probes come equipped with specific scientific instruments. The exact instruments vary based on the probe’s designated mission.


Additionally, cameras play a pivotal role, in capturing high-resolution photographs and videos. Some specialized cameras can function in low light and even capture infrared or ultraviolet wavelengths.

Temperature Control:

Given the sensitivity of the probe’s electronics, insulation, heaters, and radiators are indispensable to regulate the thermal conditions.


Lastly, the probe’s main structure or chassis encases all these components, offering them protection against dust, micrometeoroids, and harmful radiation.

Propulsion Systems

propulsion system
Photo Space Propulsion

Space probes rely on propulsion systems to escape Earth’s gravity and travel millions of miles through space. Several types are used:

Chemical rockets burn fuel to create hot expanding gases that provide thrust. They allow fast maneuvers and are commonly used for launch from Earth. Solid or liquid propellants can be used.

Ion drives accelerate charged particles using electricity for propulsion. They are very fuel-efficient but provide low thrust. Ion drives work well over long distances in space.

Solar sails use radiation pressure from the Sun as a propulsion source. Light reflects off large, ultra-thin mirrors to provide gentle but constant acceleration.

Gravity assists the use of a planet’s gravitational pull to alter a probe’s velocity and trajectory for ‘free’ propulsion. Probes can fly by planets to gain or lose speed.

Electric propulsion options like Hall effect thrusters use electricity and ionized gas to produce efficient thrust for deep space travel.

Attitude control systems with small thrusters orient and stabilize the probe as it flies through space. They allow precision maneuvering.

Each propulsion type has advantages and disadvantages based on the probe’s mass, mission goals, and duration. Multiple systems can be combined on one spacecraft.

Communication Systems

path of communication relays
Photo By Astronomy

Reliable communication with Earth is critical for space probes to transmit data and receive commands. Different systems are used depending on distance and mission needs:

Short-range probes rely on direct radio transmission and reception between the probe and Earth ground stations. But signals weaken quickly with distance.

Long-range probes use high-gain antennas to focus radio transmissions into a tight beam. Precise pointing is required.

Relay spacecraft like orbiters or landers can receive data from probes and re-transmit it to Earth. This extends range.

Probes at very far distances use directional antennas and the Deep Space Network of giant radio dishes spread worldwide to maintain contact.

Critical maneuvers are pre-programmed in advance to avoid any communication delays. But real-time commands from Earth are preferred when possible.

Advanced probes may use laser communication for high-bandwidth data transfer. But precise pointing is a challenge.

Redundant systems, radioisotope power, and fault tolerance features improve the reliability of probe communication as distances increase.

The communication system design must balance data rate, power, antenna size, pointing capabilities, and cost.

Power Sources

solar powered space probe

Space probes need reliable power to operate instruments, transmit data, and control orientation and temperature.

Solar panels power probes that explore the inner solar system where sunlight is plentiful. However, their output decreases as they move further from the Sun.

Radioisotope thermoelectric generators convert the heat from decaying nuclear material into electricity. They offer steady, long-lasting power in the dark environments of the outer solar system.

Advanced probes might use radioisotope heater units for essential components or plutonium-fueled Stirling generators for greater power demands.

Rechargeable batteries store power for times of peak demand, emergencies, and operations during eclipses or on planets’ night sides.

As a mission progresses, the available power diminishes, so designers must prioritize efficiency from the outset. They limit the use of power-intensive instruments like radar.

Researchers are developing advanced solar cells, thinner nuclear materials, and fuel cells to power future probes more effectively.

The choice of a power system hinges on factors like mission duration, distance from the Sun, radiation conditions, and spacecraft requirements.

Types of Space Probes

types of mars space probes
Photo By Richard Kruse

There are different categories of space probes designed to explore our solar system and beyond.

Flyby probes use gravity to redirect their path and study multiple planets like the Voyagers visiting Jupiter, Saturn, Uranus, and Neptune.

Orbital probes enter orbit around planetary bodies for detailed surface mapping and to study atmospheres over time, such as Cassini at Saturn.

Atmospheric probes plunge into atmospheres to directly sample composition and conditions, like the Galileo probe at Jupiter.

Landers and rovers collect data from solid surfaces, with challenges like the Mars rovers enduring dust storms and frigid winters.

Sample return probes, like Stardust and OSIRIS-REx, collect small samples to bring back to Earth for in-depth analysis.

Deep space probes, like New Horizons and Pioneer 10, push the boundaries to study the outer solar system and interstellar space.

Future probe concepts aim to explore icy moons, return samples from Mars, and even make the journey to other star systems.

Each probe is specially engineered based on mission goals, destinations, budgets, and available technology.

Sample Return Probes

mars rover collecting samples
Photo By NASA

Sample return probes belong to an elite category of space missions that collect pristine material from other worlds for study in terrestrial labs. These complex probes land, gather samples, launch back to orbit, and bring the material back to Earth in a re-entry capsule. Sample return enables a more detailed analysis than robotic instruments alone can achieve, such as dating rocks and identifying biomarkers.

The Apollo missions returned the first lunar samples, which pioneered fields like planetary geology and unveiled details about the Moon’s history and formation. Future Mars sample returns aim to determine whether life ever existed on the Red Planet by examining pristine material from billions of years ago. Returns from comets and asteroids might offer insights into the solar system’s building blocks and the origins of life on Earth.

However, executing a sample return mission demands intricate engineering and multiple launch vehicles, driving costs into the billions of dollars. If successful, the scientific return is immense, addressing gaps that no other methods can. Sample return stands as the zenith of solar system exploration.

Notable Past Space Probes

Cassini-Huygens Space Probe
Photo By De Agostini Picture Library

Space probes have revealed countless insights about our solar system over the decades.

The Mariner probes conducted the first successful planetary flybys in the 1960s, scanning Venus, Mars, and Mercury.

The twin Viking landers of the 1970s performed the first search for life on Mars and analyzed the soil and atmosphere.

Voyager 1 and 2 conducted an unprecedented Grand Tour of the outer planets in the late 1970s and 1980s, revealing stunning details we’d never before seen.

The Galileo orbiter studied Jupiter and its moons in the 1990s and deployed an atmospheric probe into the Jovian clouds.

Cassini orbited Saturn from 2004 to 2017, discovering geysers on Enceladus, methane lakes on Titan, and complex ring dynamics.

The Mars rovers Spirit and Opportunity outlived their planned 90-day missions by years, fundamentally transforming our understanding of the Red Planet.

New Horizons flew by Pluto in 2015, revealing a surprisingly complex and geologically active dwarf planet for the first time in history.

Juno arrived at Jupiter in 2016 and continues to peer beneath the cloud tops, measuring composition, gravity, and magnetic fields.

In 2021, the Perseverance rover landed in the Jezero crater on Mars to search for signs of ancient microbial life and collect samples.

Past probes have revolutionized our understanding of the solar system and paved the way for even more ambitious future missions to exotic worlds.

Each probe builds off the last, as space agencies apply new technologies and insights to open up the next frontier of discovery.

Ongoing and Future Planned Space Probe Missions

future, past, and present space missions
Photo By ESA

Several exciting space probe missions are either active or under development. The OSIRIS-REx probe is returning to Earth after it collected a sample from asteroid Bennu in 2020. The Mars 2020 rover Perseverance is exploring the Jezero crater, and the Ingenuity helicopter is scouting ahead. The Parker Solar Probe dives into the Sun’s outer atmosphere periodically to sample the solar corona.

BepiColombo is traveling to Mercury for dual orbiter and lander missions to study the innermost planet. Dragonfly will head to Saturn’s moon Titan in 2027, becoming the first rotorcraft to fly in the atmosphere of another world. Europa Clipper will fly by Jupiter’s icy moon Europa repeatedly in the 2030s and will analyze its subsurface ocean.

The Nancy Grace Roman Space Telescope will start conducting wide-field infrared astronomy from space in 2025. JUICE, an upcoming European Space Agency mission, will explore Jupiter’s icy moons Ganymede, Callisto, and Europa. Future missions plan to bring back samples from Mars, place landers throughout the solar system, and even revisit Pluto to study its geology and climate.

Space agencies are pushing the boundaries of exploration with innovative probe designs and technologies. Each mission offers new views of our cosmic neighborhood and accumulates experience for potential future human exploration.

Challenges and Limitations of Space Probes

rocket being launched
Photo By Council on Foreign Relations

Space probes must overcome many challenges and limitations to explore our solar system and beyond. The extreme distances involve very long travel times measured in years or decades. Communicating with distant probes requires large ground antenna networks. Probes experience severe conditions like intense radiation, extreme temps, and space dust collisions which can cause damage over time.

Weight and size constraints limit the instruments and power supplies probes can carry. Miniaturization of components helps maximize science return. Planetary protection protocols restrict where probes can land to avoid contaminating pristine environments like Mars or Europa. Budgets and rocket payload limits constrain how large probes can be launched. New foldable and inflatable designs allow larger structures.

Navigating precisely over vast distances is challenging. Fine course corrections en route require very precise thrusters and control. Solar power output diminishes with distance, so nuclear sources are needed for outer solar system missions. Communicating back findings and imagery from distant probes can take many hours or days at light speed. Despite these hurdles, engineers continue advancing probe technology to open new windows into our solar system and beyond.


What Do Space Probes Do?

Space probes are unmanned spacecraft that scientists launch into space to gather information about our solar system. They study planets, moons, asteroids, comets, and other celestial bodies. These probes can capture close-up images, assess atmospheric conditions, and even collect samples.

How Do We Launch Probes Into Space?

Rockets primarily launch most probes into space. These rockets generate the powerful thrust necessary to break free from Earth’s gravitational pull and set the probe on its path. Occasionally, launches occur from the Space Shuttle or the International Space Station.

How Do Satellites Differ From Probes?

While satellites typically orbit Earth or another celestial body, probes travel through space to investigate specific targets. People often use satellites for communication, observation, or data gathering, whereas probes delve into detailed studies of their chosen destinations.

Why Are Space Probes Important to Astronomers?

Space probes enable astronomers to study solar system objects directly and intimately. These probes can access locations too distant for human spaceflight. The information they gather offers astronomers invaluable insights that they cannot obtain solely from Earth-based observations.


Space probes are robotic spacecraft that scientists launch into space to explore our solar system. Consequently, they supply astronomers with invaluable data and close-up images of planets, moons, asteroids, comets, and beyond. Unlike satellites, which typically orbit specific bodies, probes are engineered to journey through space and observe their targets. Furthermore, the data these probes gather deepens our comprehension of the solar system and aids astronomers in uncovering its origins and evolution. Additionally, probes facilitate the direct exploration of distant space destinations, places too remote for human spaceflight. In conclusion, space probes serve as indispensable instruments for astronomers, unveiling insights about our solar system that remain elusive from Earth alone.

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