Stories
Slash Boxes
Comments

SoylentNews is people

posted by azrael on Sunday August 10 2014, @02:42AM   Printer-friendly
from the 2050-retirement-home dept.

An Ars Technica story contains a video and a link to the technical data [PDF] demonstrating the Low-Density Supersonic Decelerator (LDSD), which is necessary for slowing the descent of large payloads onto the surface of Mars, and is essential for any future manned mission there.

NASA's Martian robots have used the planet's thin atmosphere to their advantage while landing, slowing down through a combination of aerobraking and parachutes. But the space agency hopes to put larger hardware on the red planet's surface - eventually followed by manned exploration. Those missions will require correspondingly larger braking hardware.

As part of its technology development program, NASA [is] testing a system called the Low-Density Supersonic Decelerator. Rather than a solid shield, the LDSD has a rim of inflatable material that greatly enhances its braking capabilities when fully deployed. In addition, the system includes a large parachute that's able to be deployed at supersonic speeds.

In June, NASA launched what you could call a "falling saucer." Carried aloft by a balloon, then rocketed further into the stratosphere, the payload tested the deployment of both the inflatable heat shield and the parachute during the ensuing free-fall.

This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by frojack on Sunday August 10 2014, @04:36AM

    by frojack (1554) on Sunday August 10 2014, @04:36AM (#79554) Journal

    The rim of inflatable material didn't look very big in the video. Is this simply scaled to take into account the density of earth's atmosphere?

    In any event, it hardly seems worth the weight penalty, given that it had such little slowing effect that the parachute failed catastrophically in the wake.

    Why not more parachutes? Rockets? That has seemed to work in spite of everyone's skepticism of the skycrane approach.

    --
    No, you are mistaken. I've always had this sig.
    • (Score: 5, Informative) by gman003 on Sunday August 10 2014, @05:17AM

      by gman003 (4155) on Sunday August 10 2014, @05:17AM (#79562)

      On the Curiosity lander, the skycrane was only used for the last 220mph of deceleration. It started with just a heatshield to aerobrake, then a parachute, then the skycrane.

      Rockets are infeasible for the amount of velocity change they need. To slow purely with rockets from orbital speeds to zero is equivalent to accelerating from 0 speed to orbit. Because of how the rocket equation scales, that just isn't going to work.

      Aerobraking is a very effective way to shed a lot of velocity quickly, but it isn't good at slowing you to a stop. Parachutes enhance that, but even then, the atmosphere on Mars is thin enough that it won't be able to land safely using just parachutes. Even on Earth, most spacecraft use either a soft water landing, or retrorockets, to soften the landing even more. What this decelerator is trying to do is replace part of the heavy metal heat shield with a much lighter, inflatable shield.

      In any case, you have misunderstood the program's purpose. They are not trying some radically new methodology - they are testing refinements of a basic system that has been used on basically every Mars lander, with various final stages. Their end goal is a system that will function for landings at high altitude on Mars, such as the southern plateau. The decelerator is reported to have worked perfectly as designed. The parachute failed for unknown reasons, but considering they deployed it at Mach 2, it's not exactly an unexpected failure. That's why they're testing these things.

      • (Score: 5, Interesting) by geb on Sunday August 10 2014, @12:53PM

        by geb (529) on Sunday August 10 2014, @12:53PM (#79641)

        There are a few extra problems when you are using a rocket to slow down in atmosphere. A forwards facing nozzle catches the incoming air and compresses it, potentially damaging the nozzle, and making a much higher pressure gradient for your fuel pumps to work against. It's difficult to make a rocket engine that will work at all in those conditions, and probably impossible to make an efficient one.

        Pushing exhaust ahead of you is also a problem. If you're trying to combine aerobraking with propulsive braking, you don't want to create a hot, low density region in front of you. You'd be adding braking thrust, but losing air resistance.

  • (Score: 2) by aristarchus on Sunday August 10 2014, @08:57AM

    by aristarchus (2645) on Sunday August 10 2014, @08:57AM (#79610) Journal

    Some call it flying, we call it falling, with style! Of course the really interesting question, especially for manned flight, is how the heck do we reverse the procedure?

    • (Score: 2) by Tork on Sunday August 10 2014, @03:42PM

      by Tork (3914) Subscriber Badge on Sunday August 10 2014, @03:42PM (#79669)
      The trick is to hurl the lander at the ground and miss!
      --
      🏳️‍🌈 Proud Ally 🏳️‍🌈
  • (Score: 0) by Anonymous Coward on Monday August 11 2014, @06:23AM

    by Anonymous Coward on Monday August 11 2014, @06:23AM (#79937)

    You know what else is essential?

    Building space stations with artificial gravity (using tethers and counterweights is one possible method). Once you have that, you can test animals and then humans at Mars g for extended periods of time and have a better idea of what happens, and whether humans can actually survive Mars g.

    If any NASA scientists think one-way missions are a good idea, we should send those scientists on one way trips out of NASA.

    It's all these talk of going to mars and stupid "spend X months in a dome" research[1] that makes me not care so much when NASA's budget is cut. Nowadays too many of them seem more like parasites trying to find new ways of getting blood from their host.

    [1] You want to know about humans spending months in an enclosed environment? Ask the nuclear submarine bunch. Stop being parasites wasting public money on stupid research and directions.