Low-density supersonic decelerator

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LDSD with braking parachute, probe with and without an inflated braking device
Schematic representation of the mission

Low-Density Supersonic Decelerator ( LDSD ) was a NASA project to test new landing methods for unmanned Mars missions. During the test flights, the higher and thinner layers of air in the earth's atmosphere were used to simulate the Martian atmosphere .

background

The Low-Density Supersonic Decelerator of NASA's Jet Propulsion Laboratory is testing a new type of technology for atmospheric braking of research probes and is intended to enable higher payloads than previously possible to be deposited on the surface of Mars. The braking techniques used to date for landing Mars probes are based on experiences with the two Viking probes in July and September 1976. As the payloads increase, new approaches are required, since the technically feasible limits are reached for the braking of probes in the thin Martian atmosphere are. Therefore, the aerodynamically effective area of ​​the landing unit is increased as much as possible with the same mass , which is to be tested with the LDSD.

technology

The three-ton missiles were transported into the stratosphere by helium balloons ( Rockoon ) from the Kauai Test Facility . There the aircraft was separated from the balloon and rotated to stabilize the spin . One and a half seconds after release from the Bellongeschitt was the on the rear center-mounted star-48B- solid rocket motor ignited, brought the LDSD to a height of 55 kilometers from where it initially with four times the speed of sound to the surface rushed back . An inflatable braking device and a 30-meter supersonic parachute should slow the probe as much as possible. According to NASA, the atmospheric and technical requirements of the test series should be comparable to those in the thin Martian atmosphere .

The technology demonstrator was shaped like a popular science known flying saucer . The braking body was an inflatable collar made of extremely resistant material, arranged in a ring around the heat protection shield, which was used for the first time: It was supposed to help slow the missile to twice the speed of sound, after which the braking parachute was opened, which was supposed to reduce the speed further.

Tests and further development

Low-density supersonic decelerator after the rocket motor has ignited. (Artist's impression)
Recovery after the test flight. The solid rocket motor can be seen in the middle.

If the test series is successful, according to NASA, two to three tons of payload could be deposited on the surface of the red planet during future missions to Mars, almost doubling the payload compared to the last mission. NASA also hopes that the new technology will bring landings in mountainous regions . The first test on June 14, 2014 over Hawaii was canceled at short notice due to bad weather conditions and carried out on June 28, 2014; Two subsequent test flights are planned for the 2015 fiscal year.

First test on June 28, 2014

The first phase (ascent) of the test on June 28, 2014 was successful, the erectile tissue also achieved the calculated braking effect, but the braking parachute did not unfold completely. The LDSD test vehicle was salvaged from the Pacific after the splash. The responsible project manager, Mark Adler, confirmed that the test was rated as successful because all components could be recovered.

Second test from June 8, 2015

Since the braking parachute did not open as intended in the first test, the engineers came up with a new design. The greater segmentation should prevent the screen from tearing upon deployment. With a diameter of 30 meters, it is the largest parachute used to date for supersonic speeds. The parachute opens at speeds between Mach 2 (681 m / s) and Mach 3 (1021 m / s).

The LDSD rose as planned from Hawaii with a helium balloon to an altitude of around 37 km. The balloon was decoupled around four hours after take-off. With the help of the engine, the LDSD accelerated to Mach 4 (1361 m / s) in less than four minutes and rose to an altitude of around 55 km. The object was set in slight rotation to support a stable flight path. The cavernous body was ignited a short time later at Mach 3 and achieved the calculated braking effect. When the parachute was then deployed, it was destroyed again. 14 minutes after the engine fired, the LDSD landed in the Pacific Ocean, where it was later recovered.

The test was rated as a success because all technologies used were tried out and relevant measurement results were obtained.

Low-Density Supersonic Decelerator - Four camera perspectives of the second LDSD test flight (June 8, 2015). The earth can be seen in the background on the two pictures in the upper part and on the picture at the bottom right. In the picture at the bottom left you can see the parachute for supersonic speeds that has just been destroyed.

Web links

Commons : Low-Density Supersonic Decelerator  - collection of images, videos, and audio files

Individual evidence

  1. ↑ a b c d e No joke: Nasa launches flying saucer . Spiegel Online Science. June 12, 2014. Retrieved June 12, 2014.
  2. ↑ Latest LDSD Updates. NASA , June 12, 2014, accessed August 15, 2014 .
  3. ↑ Low-Density Supersonic Decelerator (LDSD). Raumfahrer.net, accessed on August 15, 2014 .
  4. ↑ LDSD test of Mars landing technology suffers chute failure. NASA , June 8, 2015, accessed June 20, 2015 .
  5. ^ The Supreme Council of Parachute Experts. NASA , May 27, 2015, accessed June 20, 2015 .
  6. ^ Saucer Shoal: LDSD Recovery Off Kauai. NASA , June 11, 2015, accessed June 20, 2015 .
  7. ^ NASA's LDSD Project Completes Second Experimental Test Flight. NASA , June 9, 2015, accessed June 20, 2015 .