Sorry if this is discussed elsewhere- but I couldn't find it.Skycrane method is now "proven" for landing 1 ton on the surface of Mars.Is this a feasible technique for 10 tons. What is the a mass penalty to this technique? It must mean hovering for 20 seconds or so using 6 seconds of Isp.Why is this better than putting the thrusters on the side, and leaving them there?
Why is this better than putting the thrusters on the side, and leaving them there?
For MSL it was about not contaminating the landing area with rocket exhaust. i.e. They wanted to reduce that.
Quote from: pathfinder_01 on 08/06/2012 09:15 pmFor MSL it was about not contaminating the landing area with rocket exhaust. i.e. They wanted to reduce that.That wasn't the primary consideration. It was how to deliver a rover of this size most effectively to the surface.
Quote from: alexterrell on 08/06/2012 03:00 pmSorry if this is discussed elsewhere- but I couldn't find it.Skycrane method is now "proven" for landing 1 ton on the surface of Mars.Is this a feasible technique for 10 tons. What is the a mass penalty to this technique? It must mean hovering for 20 seconds or so using 6 seconds of Isp.Why is this better than putting the thrusters on the side, and leaving them there? It is useful for other rovers. It doesn't hover for 20 seconds, only couple.It separates the lander from the payload.
It's not obvious why this is most efective method.
Quote from: alexterrell on 08/06/2012 09:41 pmIt's not obvious why this is most efective method.30:17 - 33:27 into this video: http://www.youtube.com/watch?v=SwXe_X4UKoM
1. OK. An alternative is to land a crane with rigid legs and the payload then just drives off.2. Then you've got the mass of the legs to consider. With curiosity you have no leg mass, but you have some extra fuel for hovering.From the pictures it looks like curiosity was lowered 10m or so - I'd have guessed at 1m/s, then some time to check and break the cables?3.Would it be the best method for a 10 ton manned rover? Would it be the best method for everything?
Quote from: ugordan on 08/06/2012 09:17 pmQuote from: pathfinder_01 on 08/06/2012 09:15 pmFor MSL it was about not contaminating the landing area with rocket exhaust. i.e. They wanted to reduce that.That wasn't the primary consideration. It was how to deliver a rover of this size most effectively to the surface.I can understand the contamination issue - but since the Rover is going to drive off for miles, so what?It's not obvious why this is most efective method.
Could Skycrane deliver components of MSR to the surface
Quote from: savuporo on 08/07/2012 12:07 amCould Skycrane deliver components of MSR to the surfaceWho or what is gonna assemble them?
Quote from: Go4TLI on 08/07/2012 12:14 amQuote from: savuporo on 08/07/2012 12:07 amCould Skycrane deliver components of MSR to the surfaceWho or what is gonna assemble them?I said nothing about assembly. IIRC the last reference 3-launch MSR mission required 2 rovers to be landed on surface, with the second one being in one payload with MAV
Quote from: alexterrell on 08/06/2012 03:00 pmSorry if this is discussed elsewhere- but I couldn't find it.Skycrane method is now "proven" for landing 1 ton on the surface of Mars.Is this a feasible technique for 10 tons. What is the a mass penalty to this technique? It must mean hovering for 20 seconds or so using 6 seconds of Isp.Why is this better than putting the thrusters on the side, and leaving them there? If your landing rovers or sensitive data probes that have issues with dust kicked up by rocket decent stages sky crane is the ideal method.But for large payloads, like say, pre-built habitation modules for manned stays, rocket powered decent all the way down is the ideal method.No need to add complexity if you don't have a need for it, but sky crane may be used in the future for things that don't like dust.
...The MSL landing technique is about easy egress and stability of touchdown contact. There is a very informative lecture that cured me of the "its all about being low dust" delusion located here:http://blip.tv/scvtv/scvtv-com-8-20-2009-nasa-jpl-von-karman-lecture-from-legs-to-wheels-mars-science-laboratory-s-bizarre-landing-system-pt-1-3253827
Here are some JPL design trades on the use of the sky crane.6/28/2010. The MSL SkyCrane Landing. Architecture. A GN&C Perspective. Miguel San Martin. Jet Propulsion Laboratory, California Institute of Technology .www.planetaryprobe.eu/IPPW7/proceedings/.../Session5/pr478.pdf6.4MB fileSource: public web
37 Tons to MarsHigh Mass Mars Entry, Descent, and Landing Architecture Assessmenthttp://www.ssdl.gatech.edu/papers/conferencePapers/AIAA-2009-6684.pdfPublicWeb
I do wonder if more than 1 of these parachutes can be used at once now it's been tested on Mars.Good tech should be used again.
Quote from: spectre9 on 08/07/2012 05:08 amI do wonder if more than 1 of these parachutes can be used at once now it's been tested on Mars.Good tech should be used again. no, because they would interfere with each other. Not the same as subsonic parachutes.
Is this a feasible technique for 10 tons.
Quote from: alexterrell on 08/06/2012 03:00 pmIs this a feasible technique for 10 tons. No, its not scalable. But the Skycrane could be used for future missions.
Quote from: manboy on 08/10/2012 05:27 pmQuote from: alexterrell on 08/06/2012 03:00 pmIs this a feasible technique for 10 tons. No, its not scalable. But the Skycrane could be used for future missions.Based on what do you say that the sky crane maneuver is not scalable to 10 tons?If you're not an established expert (and even if you are), you should provide a reason.The heatshield may not be scalable, the parachute might not be scalable (other things being equal), but why not the skycrane maneuver? I see no reason.
I was wondering what the MSL payload to around -7km MOLA would be. MSL landed approximately 900kg to -4.4 km MOLA. So my question is what would the payload be if MSL were to land at an area that was -7km MOLA?
As I understand it, the Skycrane was designed to land a scientific payload on ground that was not contaminated by the rocket exhaust. A manned lander or ISRU unit would not need this level of care and may actually benefit from a cleaner landing site.
As I understand it, the Skycrane was designed to land a scientific payload on ground that was not contaminated by the rocket exhaust. A manned lander or ISRU unit would not need this level of care and may actually benefit from a cleaner landing site.Mick.