IPB

Welcome Guest ( Log In | Register )

20 Pages V  < 1 2 3 4 5 > »   
Reply to this topicStart new topic
Skycrane, Innovative landing technology
Chmee
post Mar 18 2005, 06:31 PM
Post #31


Member
***

Group: Members
Posts: 154
Joined: 17-March 05
Member No.: 206



Of course with the Skycrane, if it really is going to hover around and locate a safe place to drop MSL, would need a significant amount of fuel capacity and this would add much weight. So what does the EDL to Rover weight ratio then become? Maybe as bad as the MERs

I realize that the Airbag system has reached its limit for mass, but it is hard to argue with success: 3 for 3 attempts with very different landing condiitons.
Go to the top of the page
 
+Quote Post
djellison
post Mar 18 2005, 07:35 PM
Post #32


Founder
****

Group: Chairman
Posts: 14431
Joined: 8-February 04
Member No.: 1



QUOTE (Chmee @ Mar 18 2005, 06:31 PM)
I realize that the Airbag system has reached its limit for mass, but it is hard to argue with success: 3 for 3 attempts with very different landing condiitons.

I dont think anyone is saying "airbags are crap" - I think people are saying that it's simply impossible to scale it up to the capacity needed for more able missions. Not only that, but the Airbag system is highly limited as to the terrain it can visit. Skycrane or similar isnt going to be as limited.

Doug
Go to the top of the page
 
+Quote Post
lyford
post Mar 18 2005, 07:50 PM
Post #33


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



Well, call me old fashioned, (or a broken record - which is old fashioned now that I think about it...) but I still have soft spot in my heart for the Tumbleweeds. I hope they make a fleet of these for a Scout mission, but I doubt it'll happen. Of course you would need the communications orbiter network up and running first, but it's the ultimate efficiency: the airbag IS the rover - no lost weight!

Of course, it's the very antithesis of a controlled landing and directed mission since it's at the mercy of the winds, but for mapping, magnetronomy, sounding and "ground truth" observations of harsh areas it may be just the ticket.


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
lyford
post Mar 18 2005, 08:02 PM
Post #34


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



Oooh - found a better Tumbleweed site.

Apparently I am not the only one thinking these fellas might work. Lots of good papers in the resources section....

And quite a selection:


Now I will go back on topic and kvetch about the Skycrane.... smile.gif


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
Guest_BruceMoomaw_*
post Mar 19 2005, 08:20 AM
Post #35





Guests






To Chmee: The landing hazard-avoidance system they're planning for every (fairly big) Mars lander starting with MSL doesn't "hover around and look for a safe pladce to drop MSL": it starts examining the roughness and slopes of the terrain even while the lander is still dropping via parachute, and then as soon as the chute is cut loose and the soft-landing engines start up it angles toward the safest-looking spot -- readjusting itself later if any new indications come in. Thus it utilizes far less fuel than if it came down and then started moving sideways looking for a safe landing site -- and the total weight of fuel used is still far less than the weight of an airbag system.

By the way, the US has been toying with the idea of a descent-camera controlled harzard avoidance system for a very long time -- starting with plans to put one on any Viking followups. One was originally planned for Phoenix, before it was decided that the system was too heavy and power-consuming for that mission, since it will land on a very flat and obstacle-free kind of terrain anyway. And the Selene-B lander that Japan is tentatively planning as a followup for their big 2006 Selene-1 lunar orbiter would be flown largely to test such a system. But MSL will utilize a more complex type using high-resolution phased-array radar, which can identify not only rough terrain but dangerously steep slopes of the type that a camera system might overlook.
Go to the top of the page
 
+Quote Post
remcook
post Mar 19 2005, 10:26 AM
Post #36


Rover Driver
****

Group: Members
Posts: 1015
Joined: 4-March 04
Member No.: 47



about the tumbleweed: I always wondered how you can make sensible pictures from these things. It must be one hell of a job to keep it stable and the outside must be transparent. It's not made for picture, but a thing that makes pictures is simply much easier to sell.

and what usefull things can it so except measure pressure and temperature? Nothing with a high data rate, because you won't be able to put on a high gain antenna. It's also a though job to figure out where it is (if you don't have pictures even more). You could have a sunsensor but the stability is an issue again. To obtain position accurately you'd need a GPS-like network of 3 satellites and you will only get a rough estimate.

So it's good to study dynamics, but there are maybe easier ways.

the site mentions these stop-and-go concept which seem better for pictures and higher data rates, but how would you keep your instruments from falling apart?

I think I'm more in favour of balloons cool.gif
Go to the top of the page
 
+Quote Post
lyford
post Mar 19 2005, 07:27 PM
Post #37


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



QUOTE (remcook @ Mar 19 2005, 02:26 AM)
about the tumbleweed: I always wondered how you can make sensible pictures from these things.

There are designs that allow the bags to deflate and when they want to stop and extend a sensor mast periscope style and take pix and or readings. The instruments are suspended in the center in a shock absorbing cage.

I will post more detail over in this new thread. Just trying to keep the signal to noise ratio high. tongue.gif

PS. Balloons is good too. wink.gif

And now let us speak of it no more here... back to your regularly scheduled MSL coverage.


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
DaveM
post Mar 20 2005, 10:06 AM
Post #38


Newbie
*

Group: Members
Posts: 5
Joined: 13-March 05
From: Tucson, AZ
Member No.: 192



Many of those Tumbleweed concept images were created in my undergrad senior design project. We built a 2 m diameter scale model of the "boxkite" design called TED (Tumbleweed Earth Demonstrator), though based on our calculations the real one would have to be 6 m in diameter. We even fitted a camera on TED and got some fairly decent images, though for science it would be quite limited and not very predictable. It was fun seeing that thing roll around when the wind blew, though. It was a fun concept to work on, but I kind of like balloons myself. Though you have to have enormous balloons to be able to carry a significant payload mass. One of the advantages of Tumbleweeds is that the mass constraints are not as bad as on balloons.


mars.gif+wheel.gif
Go to the top of the page
 
+Quote Post
cIclops
post Mar 25 2005, 05:57 PM
Post #39


Member
***

Group: Members
Posts: 133
Joined: 29-January 05
Member No.: 161



QUOTE (BruceMoomaw @ Mar 14 2005, 12:29 PM)
I imagine the problem is that the lander -- unless it had control of its descent speed during the last few feet of its descent too fine to be feasible with any confidence -- might actually end up pounding the rover into the surface with its own weight, thereby damaging its wheels or suspension, before unlatching from the rover and flying back up off the surface.
*


Armadillo Aerospace have recently demonstrated a very precisely controlled landing technology which shows that it is feasible. See this test flight video (7MB)


--------------------
Go to the top of the page
 
+Quote Post
lyford
post Mar 25 2005, 06:47 PM
Post #40


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



QUOTE (cIclops @ Mar 25 2005, 09:57 AM)
Armadillo Aerospace have recently demonstrated a very precisely controlled landing technology which shows that it is feasible. See this  test flight video (7MB)
*


Fake! You can see the strings! (A joke! I kid the fine people because I love...) laugh.gif
This reminded me of all the 50's sci fi movies where the big V2 style rocket backs itself down on to the moon...

Obviously they have success with a slow landing from a hundred feet on a flat pad (I couldn't find any info on the guidance control or nav they are using... GPS?), but I think the kicker is going to be the real time hazard recognition - finding a flat landing zone and going to it autonomously before the fuel runs out...

But I am glad to see the hours I spent playing Doom have led to actual benefits! tongue.gif

And now for something completely different. (2.3 MB Quicktime)


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
erwan
post Mar 25 2005, 07:04 PM
Post #41


Member
***

Group: Members
Posts: 180
Joined: 31-January 05
From: Brittany (France)
Member No.: 164



Hi Lyford: impressive link. Remenbering issues with LEM demonstration vehicle - Armstrong aboard - before Apollo 11. Finally everythings goes perfectly with the spider vehicle for successive Apollo missions!

And now for something completely different. (2.3 MB Quicktime)
*

[/quote]


--------------------

Erwann
Go to the top of the page
 
+Quote Post
lyford
post Mar 25 2005, 07:40 PM
Post #42


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



QUOTE (erwan @ Mar 25 2005, 11:04 AM)
Hi Lyford: impressive link. Remenbering issues with LEM demonstration vehicle - Armstrong aboard - before Apollo 11. Finally everythings goes perfectly with the spider vehicle for successive Apollo missions!

I never saw any video of Armstrong's trainer accident, but I also remember that they had to "fly around a bit" using up precious fuel on that first landing since the planned spot seemed too hazardous:
QUOTE
While Armstrong was maneuvering to avoid a boulder field, alarms sounded in the lunar module indicating that the computer was overloaded. Mission Control quickly told the crew to proceed. Then, as fuel was running low, a dust cloud obscured the surface and Armstrong had to touch down without a good view of his landing spot.

The MSL lander will have to be able to make this judgement in real time, but hopefully a hazard free site will be chosen with the MRO super resolution pics.

And now, a bit of nostalgia. (2.6MB quicktime) Long version here.

And since this is unmannedspacefilght.com, I apologise for that shameful display of non robotic flight, and for penance offer up this "lunar landing" movie from theRanger program:



SPLAT!


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
erwan
post Mar 25 2005, 07:48 PM
Post #43


Member
***

Group: Members
Posts: 180
Joined: 31-January 05
From: Brittany (France)
Member No.: 164



Lyford: I readed (where?, i will try to find a link)) that before real Apollo missions, Armstrong (as an 'essay pilot', is it correct in english?), see the death during a training fly with a LEM demonstration vehicle - some issue requering the "ejectable seat". Moreover, there was successive serious issues with LEM precursors, stressing the entire Apollo team. Not seen any video though...


--------------------

Erwann
Go to the top of the page
 
+Quote Post
lyford
post Mar 25 2005, 07:56 PM
Post #44


Senior Member
****

Group: Members
Posts: 1281
Joined: 18-December 04
From: San Diego, CA
Member No.: 124



QUOTE (erwan @ Mar 25 2005, 11:48 AM)
Lyford: I readed (where?, i will try to find a link)) that before real Apollo missions, Armstrong (as an 'essay pilot', is it correct in english?), see the death during a training fly with a LEM demonstration vehicle - some issue requering the "ejectable seat". Moreover,  there was successive serious issues with LEM precursors, stressing the entire Apollo team. Not seen any video though...
*

Here's the story. Astronautix to the rescue! And "test pilot" is the term I believe you are looking for in English.

And now back to unmanned flight. wink.gif


--------------------
Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
Go to the top of the page
 
+Quote Post
erwan
post Mar 25 2005, 07:57 PM
Post #45


Member
***

Group: Members
Posts: 180
Joined: 31-January 05
From: Brittany (France)
Member No.: 164



Lyford: next, your comment about Apollo 11 real landing is nice; may i add that plus the boulders area, requering Armstrong piloting, a global alarm sounded on the LEM, because descent control software was overflooded with datas rate and crashed. A young NASA engineer (name?) had the responsability to evaluate the issue in the minute, and responded to LEM team: go ahead, no problem...


--------------------

Erwann
Go to the top of the page
 
+Quote Post

20 Pages V  < 1 2 3 4 5 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 19th March 2024 - 11:11 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.