[X] My Assistant

[ljk4-1]

"And of course Surveyor 4 - did it land okay or did it crash? "

Surveyor 4 went from "nominal" to zero signal essentially instantaneously, right about the time of maximum thrust from the solid retro-rocket, a second or so before burnout.  The failure review found no smoking gun in preflight documentation and absolutely nothing in the telemetry.  They concluded that the retro may have exploded, or that there was a sudden and total power failure to two separate transmitter systems at the same time <as I recall>, which could include the entire spacecraft's power, of course.

Either it scattered shredded metal bits over a square kilometer plus of moonscape, hit the surface at the some 500 miles/hr remaining at retro burnout and lined a crater with shiny metal bits, or it more or less successfully landed or did a low speed impact after continuing a descent in the blind. 

Sinus Meridiani contains the shiny-metal-bit lined crater of Surveyor 2, the remains of 4, and successfully landed Surveyor 6.  As a very old mare with very deep.. estimated 10 meter thick.. regolith, the site has very few large loose rocks and is a generally good place to look for geologically fresh disturbances, though as old mare, the medium size crater population is large.

Assuming Surveyor 4 did not explode, could it have survived from the height it was at when the retrorockets stopped firing? By survive I mean land in more or less one piece?

Would Surveyor 4 have started an automatic program of basic exploration? Or did it need to wait for commands from Earth? How sad to think it might have been trying to send data home that no one could detect.

[edstrick]

"Meridiani? Yikes, it was off course!"

Phil: I believe <would have to check> Surveyor 2 and 4 were targeted for Sinus Meridiani, 6 finally validated that site for Apollo. Actually, I have absolutely no idea where Surveyor 2 impacted. When one vernier engine didn't fire during the midcourse maneuver, it went into a fast tumble, and every attempt to pulse the engines just increased the tumble rate.. it was up to 1 or 2 revs/second at the end.

Having lost all hope of landing Surveyor 2, they powered it up and fired the retro to exercise systems as engineering tests. The battery was nearly depleted at that time, and they lost signal sometime during the retro burn, shortly before impact. They didn't seem to really know if the LOS was due to the battery running down during high curent loads, or the vehicle disintegrating under the combined tumble and many G's of retrofire acceleration.

[edstrick]

Assuming Surveyor 4 did not explode, could it have survived from the height it was at when the retrorockets stopped firing? By survive I mean land in more or less one piece?
Would Surveyor 4 have started an automatic program of basic exploration? Or did it need to wait for commands from Earth? How sad to think it might have been trying to send data home that no one could detect.

LJK: Surveyors were STUPID. No real computer on board. They could store timing and angular info in hardware registers, so they could load parameters for a mindcourse maneuver into registers and issue an execute command and have the spacecraft turn to the loaded attitude. Another command would enable and execute the motor burn, etc.

For landing, they loaded retrofire delay time <after the altitude marking radar said "Now" for a given distance from the surface. It counted down a few seconds from then to retro, turned on the verniers, got the spacecraft stable, and lit the solid. On solid burnout, the onboard sequencer powered the verniers up to full thrust and dropped the retro-case out from under the spacecraft. The rest of the ride to the surface was automated with closed loop control systems through the range and doppler velocity radar system. All the way down, including when under power <I think> they were giving commands to switch telemetry mode, change systems power status, etc. Not much during landing, but everything else was direct from Earth command driven.

If they lost power at the time of LOS of signal, they were still miles high and doing some hundreds of miles an hour... CRUNCH.

[Phil Stooke]

Medii, edstrick! Sinus Medii... Meridiani is quite some way from there.

You are quite right, of course, about Sinus Medii being the target for both Surveyors 2 and 4 before Surveyor 6 finally accomplished the landing. Apollo planners and the Surveyor/Orbiter Utilization Committee required one Surveyor landing in each of the eastern and western maria and in Sinus Medii (plus the first landing in the vertical descent area) before they would free up a Surveyor for a 'science site'.

Phil

[Guest_BruceMoomaw_*]

Apparently Surveyor 4 lost contact at precisely the time (as indicated by ground studies) that the solid fuel in its retromotor had burned down to the point that individual loose seams between the segments of fuel attached to its chamber walls were exposed, making it highly probable that at that moment one such segment peeled loose and got blown into the nozzle, resulting in a pressure buildup and an instant explosion. There are other possibilities mentioned in the final failure report: the explosion of one of the pressurized gas tanks (or even of a shock absorber!), the breakage of a power cable, or even the breakage of a cable to the transmitters. But while the latter raises the long-shot possibility that the craft did land intact but incommunicado, the odds are overwhelming that it is now in little bitty pieces.

As for Surveyor 2: if I remember correctly it landed about 50 miles off target, thanks to the failure of its midcourse maneuver (which is where the trouble started). We don't know precisely where, since we lost contact en route -- but there was a story at the time in "Technology Week" that Lunar Orbiter 2 had photographed a fresh crater in about the right place. I don't know what that story eventually came to.

One final little historical note: Don Wilhelms says in his authoritative book on Apollo-era lunar geology, "To A Rocky Moon", that despite the failures of Surveyors 2 and 4, serious consideration was given to saying the hell with Sinus Medii and rediverting #6 to a purely scientific site -- with the plain just outside the Hyginus Rill being the front-runner. (Tycho, #7's final destination, was not on the list.) NASA HQ, however, vetoed this on the grounds that a successful Apollo mission came beyond all consideration of science.

[Bob Shaw]

Will any of the mineralogical instruments under consideration as Lunar payloads be any good at picking out the materials of which spacecraft, upper stages etc are made (especially when, er, 'well distributed' on the surface!)? It'd be nice to be able to say look, there's the Mylar, that's the paint, etc, with no room left for uncertainty or debate...

[Phil Stooke]

Bruce, that Technology Week story would be interesting... can you say any more about it?

But I wouldn't expect it to amount to anything. The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!'

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

[Bob Shaw]

Bruce, that Technology Week story would be interesting... can you say any more about it? 

But I wouldn't expect it to amount to anything.  The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!' 

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

Phil:

I think that's exactly why it'd be nice to spectroscopically identify debris fields from orbit!

Bob Shaw

[edstrick]

Medii, edstrick! Sinus Medii... Meridiani is quite some way from there.

Phil... I have a very very technical comment to make: "Duh."

[Guest_BruceMoomaw_*]

Bruce, that Technology Week story would be interesting... can you say any more about it? 

But I wouldn't expect it to amount to anything.  The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!' 

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

Completely plausible -- the only refence to it I've ever seen was a one-sentence note in Technology Week that they had seen a fresh-looking crater that was suspected of POSSIBLY being Surveyor 2. Since I've never heard anything since, I've tended to assume that it came to naught. In any case, since I saw this when I was 12, my memories are a bit fuzzy.

[Marz]

Apollo on steroids! http://news.yahoo.com/s/ap/20050919/ap_on_sc/moon_rocket

Nothing like Iraq & Katrina to show what a bargain space exploration is! Let's relocate NO to Mare Crisium!

[dilo]

‘Alpine’ landscape on the Moon: Vallis Alpes

[ljk4-1]

A Highlander Lunar Rover Mission?

See here:

http://www.nasawatch.com/archives/2006/05/...nasa_grc_h.html

[Bob Shaw]

A Highlander Lunar Rover Mission?

See here:

http://www.nasawatch.com/archives/2006/05/...nasa_grc_h.html

Poor ol' Aubrey's pages have *vanished*, but here's an image of the Highlander prototype, with batteries located within the tracks and a super-wide wheelbase, from Carnegie-Mellon University:

Bob Shaw

Attached thumbnail(s)

 

[ljk4-1]

http://www8.nationalacademies.org/cp/meeti...?meetingid=1481

Meeting Information

Project Title: The Scientific Context for the Exploration of the Moon

PIN: SSBX-L-06-04-A

Major Unit:
Division on Engineering and Physical Sciences

Sub Unit:
Space Studies Board

RSO:
Smith, David

Subject/Focus Area:
Policy & Research; Space


The Scientific Context for the Exploration of the Moon

June 20, 2006 - June 22, 2006

Keck Center
500 5th Street, NW
Washington D.C. 20001


If you would like to attend the sessions of this meeting that are open
to the public or need more information please contact:

Contact Name: Rodney Howard
Email: rhoward@nas.edu
Phone: 202-334-3477
Fax: 202-334-3701


Agenda:

PRELIMINARY AGENDA

Room 204

Tuesday, June 20

11:00 a.m.
Welcome Guests, Introductions
- George Paulikas, chair

11:05 a.m.
Talk 1: Perspective from SMD Program Management
- Mary Cleave, Science Mission Directorate Associate Administrator (TBC)


12:00 p.m.
LUNCH

1:00 p.m.
Talk 2: Lunar Sample Science and Sample Return
Charles Shearer, University of New Mexico

2:00 p.m.
Talk 3: Lunar Sample Curation
- Gary Lofgren, NASA Johnson Space Center

3:00 p.m.
BREAK

3:15 p.m.
Talk 4: Lunar Exploration Analysis Group
- G. Jeffrey Taylor, University of Hawaii, via telecon

4:15 p.m.
Discussion of Presentations
- George Paulikas and Carlé Pieters

5:00 p.m.
ADJOURN

Wednesday, June 21

8:30 a.m.
Welcome Guests
- George Paulikas, chair

8:35 a.m.
Talk 5: Lunar Geophysical Network
- Clive Neal, University of Notre Dame, via telecon from Perth

9:35 a.m.
Talk 6: Lunar Geophysics
- Norman Sleep, Stanford University

10:35 a.m.
BREAK

10:55 a.m.
Talk 7: South-Pole Aitken Basin
Brad Jolliff, Washington University at St. Louis

12:00 p.m.
LUNCH

1:00 p.m.
Discussion of Presentations
- George Paulikas and Carlé Pieters

2:00 p.m.
Discussion of White Papers
- Carlé Pieters, vice chair

3:00 p.m.
BREAK

3:15 p.m.
Discussion of Critical Near Term Lunar Science Issues
- George Paulikas and Carlé Pieters

4:00 p.m.
Overnight assignments
- George Paulikas and Carlé Pieters

4:15 p.m.
Talk 8: History of Lunar Science
- S. Ross Taylor, Australian National University, via telecon from Canberra

5:15 p.m.
ADJOURN

Thursday, June 22

The final day of this meeting is closed in its entirety.

Closed Session Summary Posted After the Meeting