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 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 near-earth asteroids launched and operated by JAXA. Hayabusa arrived at 35143 Itokawa in 2005 and returned to earth in 2010. 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.

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 releasing, 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.