[FPSPACE] FW: [lunar-update] Landing - it is in the details -

LARRY KLAES ljk4 at msn.com
Thu Dec 15 12:41:28 EST 2011

 Date: Wed, 14 Dec 2011 20:28:44 -0800
From: larry.kellogg at gmail.com
To: lunar-update at mailman1.altair.com
Subject: [lunar-update] Landing - it is in the details -

When you talk about landing humans on another planet or moon there are a lot of decisions that have to be made.  On the FPSPACE list a question was asked why the American Lunar Modules had insulation wraps on the legs and the Soviet Lunniy Korabl spaceship did not.

Soviet Lunniy Korabl spaceship in 1:5 scale at http://lunniykorabl.blogspot.com
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The LK (Lunny Korabl—"lunar ship") was a Soviet lunar lander and counterpart of the American Lunar Module (LM). The LK was to have landed up to two cosmonauts on the Moon. It completed development and was test flown successfully in Earth orbit, but never reached the Moon because development of theN1 rocket, required to take it to the Moon, was unsuccessful.

This PDF document has a lot of information about the Lunar Module landing-gear.  The 60 page NASA Technical Note explains why paint was not enough to keep the temperature within limits especially if the astronauts had to land with the rocket engine still firing as they touched down. Testing, testing, testing, and attention to detail.  And how do you drop test at 1/6 G on a 1 G Earth? :-)
- LRK -


Page 19----Thermal Insulation
Landing-gear thermal-insulation design is based on several requirements. Landing-gear temperatures must be maintained at or below design levels to ensure positive structural margins of safety and proper mechanical operation during deployment and landing. Temperature control of the honeycomb energy absorbers within specified limits is necessary to ensure that the crush loads will be within proper levels.

Based on these requirements, an estimated 8.0 pounds of thermal paint was allotted to landing-gear thermal control early in the development program. The weight history of the landing-gear thermal insulation is shown in table II. As thermal testing and analysis progressed, it became apparent that 8.0 pounds of thermal paint were totally inadequate for landing -gear thermal protection. Additional insulation had to be provided because of the effects of LM reaction control system (RCS) plume impingement, The impingement from the RCS plume adversely affected the structural temperatures and the temperature of the  honeycomb energy absorbers in the primary and secondary struts. Landing-performance analysis, for which the energy -absorber load levels that are temperature dependent were used, showed considerable degradation in landing-gear performance for worst -case combinations of honeycomb temperatures and landing conditions. The outcome of this investigation was the addition of thermal-insulation blankets to the main structural members of the landing gear. The thermal-insulation weight (table II) was increased to 29.4 pounds for the Ap0110 9 LM (LM-3) and Apollo 10 LM (LM-4), which were the first two LM flight articles to have landing gears.
[emphasis mine - LRK -]----snip--------------------------------------------------------

A lot of decisions to be made for something as big as the Apollo missions.  A lot of people and companies with their own ideas as to what would be the best way to get us to the Moon and back.  You can read about it on-line if you haven't already.  When talk about new missions that might take humans to space I wonder how much is paid to the details.
- LRK -

Chariots for Apollo: A History of Manned Lunar Spacecraft


Ch 4 Chapter 4 - Matching Modules and Missions
1962The Team and the Tools
Preliminary Designs for the Lunar Lander
Pressures by PSACFitting the Lunar Module into Apollo
NASA Adjustments for ApolloNASA-Grumman Negotiations
End of a PhaseCh 6Chapter 6 - Lunar Module
1963-1964External Design
Tailoring the CockpitHatches and Landing Gear
Engines, Large and SmallEnvironment and Electricity
The "Sub-Prime" and the Radar Problem
Guidance and NavigationMockup Reviews
The Lunar Module and the Apollo Programsnip
I took a look in this book.  Just fold everything up in a neat package until you get ready to leave lunar orbit.  Then stretch out your legs and prepare to land on soil that has only been tested by unmanned landers.  Will you slide sideways, will you sink into the regolith, will you tip over on the side of meteor crater?  Details, details, details!
- LRK -

Virtual Apollo: a pictorial essay of the engineering and construction of the Apollo command and service modules : the historic spacecraft that took man to the moon.

In the book, "Virtual LM" by Scott P. Sullivan, he has pictured on p.115, Landing Gear Thermal Insulation.  From the list of items: ... (Q) Primary Strut Thermal Covering (1/2 mil Aluminized Kapton), (Q2) Primary Strut Thermal Covering (5 mils Aluminized Kapton), (R) Landing Pad Thermal Covering (1/2 mil Aluminized Kapton), (S) Probe Thermal Coating (2 mils Aluminzed Kapton).

On pages 75 - 92 he has pictured the Landing Gear Assembly in its various configurations.  Looks like a lot of electrical and mechanical considerations.

On page 77 Scott has a write up about the landing gear and in the last paragraph he states, "The landing gear primary strut had a footpad at the bottom that was 37 inches in diameter and was attached to the strut with a ball-socket fitting, allowing radial movement.  The landing pad was an aluminum honeycomb construction and its large diameter ensured minimal penetration of the LM on lunar impact.  During launch, four straps held the pads in a fixed position on the strut.  The straps would shear or bend on impact with the lunar surface, permitting the pad to conform to the irregularities of the lunar surface."

On page 83 Scott has a paragraph about the lunar surface-sensing probes that were on on three of the four landing struts.  They were retained in a stowed position up against the primary strut until landing gear deployment.  During the deployment, mechanical interlocks were released permitting spring energy to extend the probes so that they were approximately 5 feet below the bottom of the footpad.  Pressure on the probe head completed an electrical circuit letting the astronauts know to shut off the engine.
And how much weight will you have to add to protect you from radiation from space?  Will you want to land on legs?  How many legs?  If you land on an asteroid, do I need legs?  If I land on Mars, do I need legs?  Those details.

Thanks for looking up with me.
- LRK -

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New Scientist TVAquanauts prepare for asteroid landing

15:22 6 December 2011

NASA is preparing for the next frontier: an asteroid landing. Due to the weak gravity and loose surface of these space rocks, travelling across the rocky terrain will be a challenge. So in October, the NASA Extreme Environments Mission Operations (NEEMO) team tested how cables, jet packs, and poles could help people move over the surface of a simulated asteroidnear Key Largo, Florida.  

In this video, David Saint-Jacques of the Canadian Space Agency tries out a small telescoping boom, a method that should provide the stability necessary in zero gravity. The pole is fastened with magnets to anchor points on the surface. By inching from one of these points to the next, he slowly but steadily approaches his destination. 

To find out more about asteroid exploration, read our full feature Asteroid touchdown: mission to a mini-world. If you enjoyed this video, watch a simulated Mars walk or check out a 3D moon flyover. 

New Scientist TV3D moon flyover reveals greatest detail ever

16:22 22 November 2011

This flyover of the lunar surface gives the most comprehensive picture of the moon to date. Created by researchers at the German Aerospace Center (DLR) and NASA, the virtual ride is made up of 70,000 still images captured by a wide-angle camera aboard the Lunar Reconnaissance Orbiter (LRO) from an altitude of 50 kilometers.

The model highlights low-lying areas in blue and the highest regions in red and white. In the first clip, a full view of the lunar surface initially reveals the Earth-facing side of the moon, showing prominent flat plains that were used as landing sites for the Apollo missions.

As the model rotates, the dark side of the moon, which faces out toward space, becomes visible. It's home to the lowest crater, roughly 9100 metres deep, as well as the highest mountains that reach an altitude of 10,760 metres.

Subsequent clips zoom in on the South Pole-Aitken basin, a large impact crater on the far side of the moon, and the landing sites of Apollo 15 and Apollo 17.

The virtual flyover took two weeks to create and covers 98 per cent of the lunar surface.
Frank Scholten, a geodesic scientist at DLR, used a network of 40 computers outfitted with special software to compare still images from the LRO pixel by pixel. A 3D model was obtained by analysing the point of view of the camera in each shot as well as data from a laser-mapping instrument onboard the LSO. Laser readings were used to map topography at the poles, which is difficult to do otherwise due to persistent shadows.

"These 3D maps of the moon enable us to better evaluate future landing sites," says lunar researcher Ulrich Köhler from the DLR, who is part of a team working with NASA to survey the moon. "Whether manned or unmanned, future flights to the moon will benefit from the most detailed map of the lunar surface," he says.

If you enjoyed this video, watch how the LRO mapped the surface of the moon, see ananimated map of the largest lunar craters or take a mind-bending tour of the solar system.


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