Uncrewed Capsules

Uncrewed missions to LEO

Not all missions that enter Earth orbit and return carry a crew. Some missions carry experiments to LEO and return them safely. These missions can be flown on uncrewed crewed platforms such as the SpaceX Dragon capsule and the Russian Foton capsule. Others, such as Space Rider and X-37 have been developed especially for an uncrewed mission.


Operator: Arianespace

Mission: Reusable upper stage

First flight: 

Status:  Conceptual design

SUSIE (Smart Upper Stage for Innovative Exploration [196]) is a proposal for a multi-functional spacecraft being developed by ArianeGroup, Avio and Rocket Factory Augsburg (RFA) with funding provided by the New European Space Transportation Solutions (NESTS) programme of the European Space Agency [197]. Proposed uses include manned flights, either free-flying or delivering crew to space stations, unmanned station resupply missions, the deployment of satellites or even in-space manufacturing and on-orbit refuelling depots [198]. Initially, SUSIE is being developed to fly on Ariane 64, weighing up to 25 tonnes on lift-off, but it could also be used with future launch vehicles to go beyond low Earth orbit [196].

In terms of EDL systems, SUSIE’s fuselage is a lifting body which decreases deceleration loads on its crew and payload. Unlike its smaller predecessors IXV and Space RIDER, which are also lifting bodies but use a large parafoil for landing, SUSIE does not carry any parachutes. Instead, it is designed to perform a propulsive landing after re-entry using landing legs, aerodynamic control surfaces and controllable engines. Ejection seats for the crew are also included in the design. SUSIE can carry up to 5 astronauts or 7 tonnes of cargo inside its 40 m3 cargo bay, both on ascent and on descent [196].

Render of SUSIE landing
Render of SUSIE landing
Render of SUSIE in space
Render of SUSIE in space
SUSIE on top of Ariane 6 at the Space Tech Expo
SUSIE on top of Ariane 6 at the Space Tech Expo


Operator: Roscosmos

Mission: Experiments in microgravity

First flight: 1985

Status:  Active

The Foton satellite program is a Russian platform for microgravity research. The satellite is launched onboard a Soyuz rocket and re-enters like the Vostok capsule. That means that the heat shield is all around the capsule, and the vehicle entries ballistically. The last Foton mission was flown in 2014 as Foton-M4, and the Foton-M5 mission is set for 202x.


Operator: Soviet Union

Mission: Spy satellite with separate return capsules

Test flights: 1974 - 1977

First flight: 1977-2015

Status:  Retired

The Zenit spy satellite had been providing the USSR’s intelligence agency with photographic data from orbit in the early days of the Cold War, similarly to the USA’s Corona spy satellites. However, there was a need to develop an improved spy satellite that could match the capabilities of the USA’s KH-4A satellites. Design work on this new spacecraft began in 1964 and would eventually lead to the Yantar class spy satellites, which entered service in 1977. [171]

Chronology of the Yantar spy satellite family.
Yantar spy satellite

Many variants

After the success of the Yantar-2K vehicles, the work on an improved vehicle would begin, eventually leading to a whole family of Yantar variants. The first improvement was the instalment of an improved camera and an extended mission duration from 30 to 45 days which would be called Yantar-4K1 “Oktan”. More improvements were made on subsequent variants, such as the Yantar-4K2 “Kobalt” and later the Yantar-4K2M “Kobalt-M”, which had a mission lifetime of 120 days. 

Chronology of the Yantar spy satellite family.

Yantar satellite, featuring two SpK spherical return capsules and the recoverable special intrumentation module (central section in brown)

The first operational version, Yantar-2K “Feniks” had a conical shape to which two spherical return capsules (SpK) of 0.8 meters in diameter were attached. Throughout its operational lifetime of 30 days, the vehicle would photograph places of interest on film rolls. The first of the two spherical capsules re-entered after ten days in orbit to allow for a fast return of the photographic data. The second spherical capsule returned after 18 days in orbit. A small solid rocket booster and sets of spin-up thrusters guaranteed a controlled re-entry, followed by a parachute-assisted landing. [172]

At the end of the mission, after 30 days in orbit, the special instrument module of the satellite detached itself to deliver the last photographic film roll, as well as the onboard camera, which could then be reused on the next flight. Therefore, this return capsule was equipped with a heat shield and parachute landing system, similar to that of Voskhod. A solid rocket motor with four nozzles was installed on the parachute riser to provide additional deceleration to guarantee a soft landing. [172]

The development of the first version, Yantar-2K, was far from troublesome as it was plagued with launch vehicle failures, malfunctioning solid rocket motors, and a failed parachute deployment. On the sixth flight test in 1977, thirteen years after the project kick-off, all systems of Yantar-2K proved to work as intended. After this difficult start, the family of Yantar spy satellites was operational for almost 40 years, with roughly 179 launches. [172]

The latter would still be used well in the 21st century, up until its decommissioning in 2015. There has also been a hybrid configuration between Yantar and Zenit, such as for example the Yantar-1KFT “Kometa”, which featured a Yantar architecture with a Zenit return capsule, operating as a cartographic satellite. Not much is known about how much the entry, descent, and landing architecture of these Yantar variants deviates from the one that was developed for Yantar-2K. [172][173]

In the ‘80s, the Yantar-4KS1 “Terilen” variant was also introduced, which used digital data transmission instead of return capsules. This allowed for a significantly longer mission duration of 207 days, which later increased to 259 days for the improved version, Yantar-4K1M “Neman”. These satellites laid the foundation for future digital spy satellites of Russia, such as Persona.

Bion and Bion-M

Operator: Roscosmos

Mission: Biological experiments in microgravity

First flight: 1973-1996 (Bion), 2013 - active (Bion-M)

Status:  Active 

The Bion program was started in 1973 to perform biological research. The satellites carried all kinds of biological experiments on various living species ranging from fungi and plants to monkeys and tortoises. On average, the missions lasted 22-days. The return capsule was a modified Zenit-2 re-entry capsule. However, due to the Zenit-2 being a spy satellite, information is rather scarce. What can be assumed is that the cameras from the Zenit-2 were removed to make space for the experiments and also their life-support.

The Bion program ended in 1996 and was followed up by the Bion-M program. This has its first flight in 2013. This re-entry capsule is based on the Vostok capsule (link to chutes Vostok page). The capsule was also modified for biological experiments. However, compared to the original Bion experiments, the experiment's lifetime was extended to 6 months, and the scientific payload was increased by 100 kg. However, the first Bion-M mission only had a mission duration of one month. The second Bion-M mission was scheduled to be launched in 2020 but was delayed until 2023. [20, 21]

Bion-M spacecraft


Operator:  USAF/DOD

Mission:  Spy capsule recovery

First flight: 1956

Status: Cancelled

In the midst of the cold war, aerial espionage was key for the United States to gather intelligence on the USSR’s capabilities. The U-2 spy planes had been flying successfully over the Soviet Union for many years, however the idea of using a spacecraft for espionage was very promising. Therefore the Corona spy satellite program was initiated in 1956. These satellites were tasked to fly over the USSR multiple times and then return the footage to the US. The missions were also named ‘Discover’ as a cover for the public, to whom was said that the objective was to fly scientific payloads to space, which did occasionally happen.

The re-entry capsule was a blunt cone with a spherical front, also referred to as ‘bucket’,  and used a two-stage parachute recovery system. A drogue chute decelerates the capsule, after which the main deploys. Instead of a water landing, an aircraft would snatch the capsule by catching the parachute mid-air. This proved to be challenging and often required multiple attempts per capsule, even with a trained pilot. Three different main parachute designs have been flown on the Corona capsules in an attempt to improve the mid-air capture success rate, although without much success. Apart from the mid-air recovery aircraft, there were ships and helicopters present within the recovery area to capture the capsule in case of a splashdown. These proved to be necessary in multiple occasions when the vehicle was off-course and landed outside of the recovery area. The retrieval experience gained during the Corona – Discoverer program proved very valuable during retrieval of the Apollo missions.

The Corona – Discoverer program was one with many failures and challenges that had to be tackled because of the fact that rocketry and satellites were a relatively new and unexplored territory of engineering. One of the early flights, Discoverer-8, encountered a failure that was attributed to the recovery system, where the parachutes failed to deploy, leading to a loss of the vehicle.  It was Discoverer-13 that successfully launched, entered orbit around the Earth and became the first man-made object to be recovered from Earth orbit in 1960, only 9 days before the USSR achieved the same result with one of the Sputnik probes. Although considered successful, the capsule's recovery didn’t go as planned: the capsule landed too far from the recovery aircraft and had to be quickly recovered by helicopter before it sank. The first mid-air recovery of the corona capsule was Discoverer-14.

Although many flights never returned safely or even didn’t reach space, the Corona satellites managed to provide valuable footage of the USSR. After the last flight of a Corona spy satellite, in 1972, the KH-9 Hexagon spy satellite continued to provide footage for the United States. The satellite carried multiple corona-like capsules that it could deploy at different moments in time. [30, 31, 32]

Corona capsule captured in mid air

Fanhui Shi Weixing

Operator: China

Mission: Recoverable satellite 

First flight: 1974

Status: Retired

Much like the US Corona and the Soviet Zenit satellites, China had their own recoverable satellite called Fanhui Shi Weixing. Their main objective was to act as spy satellites, later variants also served as biosatellites much like the Soviet Bion capsules. One interesting feature was the thermal protection of the FSW satellites, this was done using impregnated oak. This allowed for quickly produced ablative thermal protection. 

The FSW satellites also briefly served as the baseline for China's second crewed capsule after the Shuguang spacecraft was cancelled. However, some sources suggest that this program was solely for propaganda purposes and never designed for operation. 

Fanshoi Shi Weixing before launch


Operator: ASI

Mission: Experiments in microgravity 

First flight: Unflown 

Status: Cancelled

The CARINA Space System (CApsula di RIentro Non Abitata [138], meaning ‘uninhabited re-entry capsule’) was a project of the Italian Space Agency (Agenzia Spaziale Italiana, ASI) that was started in 1990 [139] with the aim of developing a spacecraft that could carry microgravity experiments into orbit and return them to Earth. The spacecraft, which would have had a lift-off mass of approximately 600 kg, would carry up to 165 kg worth of experiments into a 360 km orbit [138]. While in orbit, the experiments would be supported by a service module. Five days into the mission, the vehicle would perform a deorbit manoeuvre, and the service module would separate at an altitude of approximately 130 km [138]. The re-entry capsule, which was of the blunt body type, would safely carry the experiments through the atmosphere until the speed had decreased enough for the parachutes to be deployed, after which the vehicle would splash down in the Indian Ocean [138]. No further information about the parachute system is known, and the project was cancelled in 1995 [139].

CARINA capsule [140]


Operator: NASA

Mission: de-orbit demonstrator

First flight: 2012-current

Status: Active

To develop and improve technologies for small satellites, the Technology Educational Satellites are launched. These missions have the final goal of using and possibly land a small satellite on Mars or another planetary body [35]. Over the course of the past eight years, nine satellites have been launched, TechEdSat 1-8, and 10.

From TechEdSat 3 onwards, they include a passive exo-atmospheric de-orbit device, or in simpler terms, a parachute to be used in space environments for de-orbit, named Exo-Brake. This mylar parachute is deployed from the back of the satellite, aiming to replace the more complicated de-orbit systems, like thrusters, for small satellites. IT has a cross-shape and is supported by a hybrid system of mechanical struts and flexible chord. From TechEdSat 5 onwards, a control system was included that allowed the shape to be controlled in flight, much like the wright brothers did on their initial wing design [33]. The space-parachute onboard TechEdSat 5 had a size of approximately 0.35 m² and has a cross-shape.

The latest iteration TechEdSat, launched in 2020, has the largest Exo-Brake to date [37]. The Exo-brake can now be controlled from the ground to achieve a targeted re-entry and landing location. This should be useful for the de-orbit of satellites and sample return missions.

Exo-Brake parachute unfurling in space

RED capsules

Operator: SpaceWorks

Mission: Sample return capsule

First flight: 

Status: In development

The RED-25 capsule or Re-Entry Device with a payload capability of 25 kg. The organisation behind this capsule is SpaceWorks, an Atlanta-based company which houses legacy members of both Generation Orbit and Terminal Velocity Aerospace. RED-25 is designed to be carried towards orbit, after which it will provide weightlessness experiments that can be returned to earth and other types of sample and cargo return. The capsule weighs about 15 kg and is 1 meter in diameter. For safe landing, the capsule is equipped with a guided parafoil for precision landing [156]. 

SpaceWorks is working on a family of capsules including RED-50, RED-25, RED-12, and RED-8. The smallest has a diameter of about 0.5 meters and the larger capsule has a diameter of 1.3 meters. No orbital flights have been performed to date, however, the company conducted several drop tests that seem to be successful. Besides offering missions with a single payload the company is considering a RED-4U mission which holds four cubesat-style payloads, this capsule seems to be based on the RED-8 configuration as the total payload mass indicated is 8 kg [157]]. 

A smaller version of the RED capsules is the RED-DATA2. This capsule comes in with a diameter of 23cm and a height of 19 cm. The shape of the vehicle is very similar to the others but the mission is geared more towards TPS testing, atmospheric re-entry data gathering and flight environment profiling. Three RED-DATA2 capsules were included in the S.S. John Glenn Cygnus capsule. After Cygnus broke up due during re-entry the RED capsule did not communicate anything back to earth. Terminal Velocity Aerospace, the operator at that time, made several recommendations for future flights. [158, 159]