11
$\begingroup$

How does the New Shepard Crew Capsule sense proximity to the ground in order to trigger retropropulsion just before impact?

GIFs from Blue Origin NS-10: New Shepard launch & landing, 23 January 2019

For example, Soyuz uses a gamma ray altimeter for several reasons:

Blue Origin NS-10: New Shepard launch & landing, 23 January 2019

Blue Origin NS-10: New Shepard launch & landing, 23 January 2019

For reference:

Soyuz MS-08 landing

GIF from Soyuz MS-08 landing

$\endgroup$
4
  • 1
    $\begingroup$ on a new landing system but the talking head didn't give away any secrets. $\endgroup$
    – Woody
    Dec 15, 2021 at 7:08
  • 1
    $\begingroup$ Early Russian Voskhod capsules used a telescoping rod sensor. Contact with the ground triggered the landing rockets. Usually. But testing revealed reliability problems under challenging landing conditions. The early gamma ray altimeter used in Soyuz had a Cobalt-60 radioisotope gamma source rtc-ru.translate.goog/solution/kaktus/… In 1975 the radiation source was switched to Cesium-137. books.google.ca/… $\endgroup$
    – Woody
    Dec 15, 2021 at 7:08
  • 2
    $\begingroup$ I could find no published information of the type of proximity fuse used by New Shepard, but there are significant safety issues with cesium-137. Cobalt-60 is more civilian friendly but the presence of a gama source would complicate emergency efforts in case of a landing accident. Fools rush in and all that. Proximity fuses have been used extensively in artillery shells since WWII. Radio frequency sensors are robust enough to be launched inside artillery shells. If I were a paying Blue Origin passenger, I would rather share a capsule with a radio than a gamma source. Recent news coverage menti $\endgroup$
    – Woody
    Dec 15, 2021 at 7:08
  • 2
    $\begingroup$ @Woody The problem is not in reliably detecting the ground, but in reliably not detecting not-ground. Bad things would happen if your proximity sensor was triggered by vegetation. $\endgroup$ Jul 8, 2022 at 4:39

1 Answer 1

4
+50
$\begingroup$

New Shepard had two separate sensors for ground proximity, for its flights on 2020 Oct 13 and 2021 Aug 16.

Section III of New Shepard Flight Test Results from Blue Origin De-Orbit Descent and Landing Tipping Point, by Bieniawski et al, AIAA 2022-1829, reports:

The final set of sensors included the NDL [Navigation Doppler LiDAR] from NASA Langley, the DLC [Descent and Landing Computer] from NASA JSC, and the OMPS [Optical Moon Proximity Sensor] procured from OADS [Optical Air Data Systems]. The NDL consists of an electronics box and laser connected by fiber optic cables to three telescopes mounted at fixed angles within one of the transition tunnels.
The NDL sends near infrared (1550 nm wavelength) laser beams to the surface, and the reflected returns are detected to provide an estimate of the lander’s velocity and range relative to the ground.
...
The OMPS ... consists of a small electronics box and four telescopes. The measurement principle, while still a LiDAR at 1550 nm wavelength, is different from the NDL and leverages OADS’s years of development in terrestrial LiDARs for wind turbines, helicopters, and aircraft.

The NDL LiDAR is documented here.

The NDL was the one used for real-time navigation, while the OMPS's measurements were only recorded for post-flight evaluation.

Correction: The NDL and OMPS were mounted near the top of the booster, rather than on the crew capsule, as shown in part of figure 4 in the paper (below), and as implied by figure 12 which is a photo of the booster just before landing annotated with laser directions.

figure 4 of the paper

Blue Origin's fact sheet says that

Right before touching down, a retro thrust system expels a cloud of air beneath the capsule to create a gentle landing around 1 mph in the West Texas desert.

This retropropulsion (not a rocket, just a tank of compressed air?) must be commanded by software just like all aspects of its flight. But I don't know what kind of sensor triggers that command.

$\endgroup$
3
  • 2
    $\begingroup$ Moon Proximity? $\endgroup$ Jul 7, 2022 at 21:14
  • 3
    $\begingroup$ Yep. This report says it's intended for the Blue Moon Commercial Lunar Lander, and the New Shepard flights were testing it for that. But I understand your confusion :) $\endgroup$ Jul 7, 2022 at 22:12
  • 2
    $\begingroup$ Were these used on the crew capsule? It seems to only be for the booster $\endgroup$ Jul 8, 2022 at 12:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.