Sample Return Capsules

The Soviet Luna program was a set of Russian moon missions ranging from orbiters to landers, to sample return missions. The details of the program can be found here. This section of the web page describes the earth lander used for the mission. Luna 16, together with Luna 20 and Luna 24 returned several hundred grams of lunar dust. The entry capsule resembled the Vostok capsule as a round spherical entry shape using a single parachute. As the entry was ballistic it experienced 450 g's before deploying the parachute afterwards.

The soviet union completed three other sample return missions in total which were Luna 16, Luna 20 and Luna 24. All used a similar earth entry vehicle. 

The Genisis mission was tasked with gathering samples from solar winds and returning them to Earth for studies. The capsule, about 1.5 meters in diameter and 225 kg, was to be recovered with a two-stage parachute system. The first parachute would be a drogue, where the second was to be a lift generating parafoil. The parafoil would not bring the capsule back to the ground but instead would be captured in mid-air. This "Mid Air Retrieval" or MAR had been shown during the Corona spy satellite missions. Genesis performed an almost ballistic entry, assuming an angle of attack of about 2.5 degrees. 

The parachute system of Genesis was, unfortunately, not deployed successfully due to a faulty sensor. This means that the capsule crashed into the earth at about 86 m/s. Later it was seen that one of the accelerometers was installed backwards. Thus the electronics never determined the moment of atmospheric entry. The hard landing was something the capsule was not designed for. However, the samples were intact and could still be studied.

The Hayabusa mission was a sample return mission to a near-earth asteroid launched and operated by JAXA. Hayabusa arrived at 35143 Itokawa in 2005 and returned to earth in 2010. More on the astroid side of teh mission can be found here. The about 15 kg capsule entered the atmosphere with 12.2 km/s and followed a ballistic entry. During the entry, the capsule experienced a 40 g deceleration pared with about 1500 W/cm2 thermal flux.  A parachute was added for a safe landing. The rest of the satellite entered the atmosphere in an uncontrolled manner and was destroyed. 

The Hayabusa 2 mission is the successor to successful the Hayabusa mission, which launched in 2013. The HII-A launcher lifted off in December of 2014 with the Hayabusa spacecraft onboard. The plan was to land two small rovers, take some samples and return these back to earth, and do some impact testing. All this was to be done on the 162173 Ryugu near-earth asteroid[104,105]. The spacecraft rendezvoused with the asteroid in 2018, where it would stay for the next 1.5 years to perform the various scientific objectives it had. In November 2019, Hayabusa left the asteroid with onboard some samples to be analysed back on Earth. More on the astroid side of teh mission can be found here.

In December 2020, the spacecraft arrived back near the Earth, releasing the re-entry capsule with the samples. This capsule had a diameter of 40cm and a height of 20cm and weighed 16kg. It re-entered the atmosphere with a speed of 12km/s. During re-entry, the heatshield reached 3000C on the outside while staying 80C inside [3]. After re-entry at about 10km altitude is released the heatshield and deployed a cross parachute. Because of the small size of the capsule, the parachute was made radar-reflective [104,106]. After landing, the capsule had travelled a total of 35AU (35x distance Earth-Sun) [104].

Although this was the end of the sample return part of the Hayabusa 2 mission, it is not the end for the spacecraft. After release, the spacecraft fired its thrusters to extend its mission to rendezvous and explore different asteroids [105]. As of writing (November 2021), the spacecraft travelled over 41 AU [105].

The Stardust mission brought back samples from the trail of a comet. The mission was the first sample return mission of it's kind and landed on Earth in 2006. Onboard was an aerogel with the samples that were gathered. The mission entered the atmosphere with 12.9 km/s, the fastest entry speed ever achieved on earth. In comparison, the Apollo 11 mission entered the atmosphere at about 11 km/s, and  Soyuz re-enters at 7.618 km/s. During the entry, Stardust encountered a peak deceleration of 34 g's at an altitude of 55 km. The PICA heat shield reached a temperature of 2900 deg C! 

Not much information can be found on the Stardust parachute system. From images, it can be seen that the system uses a drogue and main parachute, thus a two-stage parachute system. However, an interesting fact from NASA is that the aeroshell (the spacecraft body itself) reduced the kinetic energy by 99%. This nicely shows that the parachute system's goal is primarily the safe landing and not the majority of the deceleration.

OSIRIS-REx is the first U.S. mission to collect a sample from an asteroid and return it to Earth. The mission's name stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer. The spacecraft launched in 2016 and reached its destination, asteroid Bennu, in 2020. Bennu is a near-Earth asteroid that is about 500 meters across and has a dark, carbon-rich surface. Scientists are interested in studying Bennu because it may contain clues about the origin of life and the solar system.

OSIRIS-REx performed a daring manoeuvre to collect a sample from Bennu's surface in October 2020. The spacecraft briefly touched down on a site called Nightingale and used a robotic arm to blast the surface with nitrogen gas, stirring up dust and rocks that were captured by a sample collector. The spacecraft then backed away and stowed the sample safely in a capsule.

The capsule was recovered by a team of NASA and Lockheed Martin personnel and flown to NASA’s Johnson Space Center in Houston, where the sample material inside it will be cared for, stored, and shared with scientists around the world. The sample is expected to weigh at least 60 grams (2 ounces) and may contain up to 2 kilograms (4 pounds) of asteroid material. NASA has identified the cause of the parachute problem that occurred during the return of the OSIRIS-REx asteroid sample capsule on Sept.24, 2023. The issue was likely caused by crossed wires in the parachute release system, which resulted in the drogue chute deploying out of order and detaching from the capsule. However, the main chute was able to stabilize and slow down the capsule, ensuring a safe landing and preserving the precious sample of asteroid Bennu. The sample is now being processed at NASA’s Johnson Space Center in Houston, where scientists hope to learn more about the origin and evolution of the solar system and the potential for life on other worlds. The OSIRIS-REx mission was the first U.S. mission to collect and return a sample from an asteroid.

The sample from Bennu is important because it can help us understand how planets formed and how life began. Bennu is one of the oldest and most primitive bodies in the solar system, dating back to more than 4 billion years ago. It may contain organic molecules, water, minerals, and other substances that are essential for life. By analyzing the sample, scientists can learn more about the history and evolution of Bennu and other asteroids, as well as the role that they may have played in delivering the building blocks of life to Earth. [191,192,193,194,195]