Tuesday, December 11, 2012

Apollo+40: The First EVA - A Flag Returns

When Apollo 11 Astronauts Neil Armstrong and Buzz Aldrin landed their LM Eagle in the Sea of Tranquility on July 20, 1969, they brought three flags with them. One was left there at the landing site, and two were returned to Earth. One of the flags that was returned was displayed in Mission Control in Houston until a short time before the flight of Apollo 17. That particular Stars and Stripes were stowed aboard Challenger for a return voyage to the Moon.

So far, we have met the crew of Apollo 17, launched with them, journeyed to the Moon, and landed. Forty years ago from the time of this post, the first of Man's three final excursions for discovery on the lunar surface began.

Command Module Pilot (CMP) Ron Evans maintained America in lunar orbit and conducted his own scientific program with the instruments onboard her while Commander (CDR) Gene Cernan and Lunar Module Pilot (LMP) Jack Schmitt prepared for their first EVA, just four hours after their landing at Taurus-Littrow.

The A7LB space suit model worn by Cernan and Schmitt on the lunar surface had also been used on the two previous "J" missions: Apollo 15 and Apollo 16. The suit was designed to be more comfortable and capable for the extended lunar stays of the later flights. The astronauts further benefited from being able to take it off inside the LM between EVAs.

At 117:01:49 Ground Elapsed Time (GET)/6:54 PM EST, mankind's last two Moon walkers depressurized Challenger, and began the first of the final three lunar EVAs.

The Apollo Program was executed for national and international prestige, but also for true scientific discovery. Jack Schmitt, a geologist, was the first scientist-astronaut to fly on any mission and NASA made completely the correct decision to place him on the Apollo 17 crew when the later lunar missions were cancelled. The value of having a scientist in space was found almost immediately with Schmitt's observations of Earth during the trip to the Moon. Schmitt had worked for years to both prepare his fellow Moon walkers for their geology tasks and learn their trade as pilots. He had already proven his worth as a pilot; now he'd get to be the only lunar geologist to work on a field site first hand.

A short time after opening the LM's hatch, the final two lunar explorers reached the surface.
117:11:09 Cernan: I'm on the footpad. And, Houston, as I step off at the surface at Taurus-Littrow, we'd like to dedicate the first step of Apollo 17 to all those who made it possible.
About four minutes later when Schmitt descended Challenger's ladder, his first words were a tongue-in-cheek-criticism of his Commander:
117:15:17 Schmitt: Hey, who's been tracking up my lunar surface?
The two immediately set themselves to work surveying their landing site. Cernan walked over to a crater he had named "Poppie" (for his father) before the flight. Poppie was one of Apollo 17's approach landmarks and was about 100 meters away from Challenger. For contrast, the longest distance Neil Armstrong on Apollo 11 was away from Eagle was about 60 meters.

Meanwhile, "Dr. Rock" as he was known by his fellow astronauts, was in geological seventh heaven:
117:21:54 Schmitt: Looks like a vesicular, very-light-colored porphyry of some kind; it's about 10 or 15 percent vesicles. I'm right in front of the LM. Quite a few of the rocks look of that type. Sort of a pinkish hue to them. The texture is coarse, but I'm not sure how crystalline they are, yet.
Their initial observations of Taurus-Littrow complete, at 117:25 the pair began a procedure on which all hopes for their three days on the Moon would rest: deploying the Lunar Roving Vehicle (LRV).

The LRV had been carried to the Moon hung on the side of Challenger's descent stage (picture here). Cernan & Schmitt used cables, straps, and pulleys to deploy their "Moon buggy", which automatically unfolded as it was lowered to the surface. They sucessfully checked out the LRV and found it in good shape. They'd be able to drive around Taurus-Littrow, rather than just walk! Cernan couldn't see behind himself on the first test drive, but he could tell that at least half of the LRV's four-wheel steering was working just fine:
117:47:50 Cernan: Okay. I can't see the rear ones, but I know the front ones turn. And it does move. Hallelujah. Hallelujah, Houston! Challenger's baby is on the roll. 
117:48:04 Parker (Bob Parker, CAPCOM): Roger. Copy that. Sounds great.
Thus far, no one on Earth had seen the last two lunar voyagers on the surface. To save weight, Apollo 17 only carried one TV camera to the lunar surface, to be mounted on the LRV. Cernan accomplished this along with loading the rover with equipment they'd need on their first geology traverse later in the EVA. Schmitt was unloading more gear from the LM's descent stage - the Apollo Lunar Surface Experiments Package, or ALSEP.

At 118:14, Ed Fendell ("Captain Video" to those in NASA) began remote control of the TV broadcasts from the Moon. Cernan and Schmitt then moved on to the next task in their checklists: raising the American flag...more on that later.

After the flag was up, Schmitt carried the ALSEP gear to its deployment site a short distance away (about 200 meters) from Challenger. The equipment contained six major experiments, plus an array of geophones that would receive sound waves transmitted through the lunar crust by small explosive charges that the astronauts would place on their lunar traverses. The ALSEP gear was powered by a radioisotope thermoelectric generator (RTG) so it would continue to have power during the lunar night.

Unfortunately, as Schmitt was off with the ALSEP gear, Cernan snagged a piece of his equipment on the LRV's left rear fender, and tore it off.

Cernan knew based on the experience of Apollos 15 and 16 that the rover kicked up a lot of dust while driving, and that the fender had to be repaired if possible. He did so, with (yes!) duct tape.

The following video is about two and a half minutes from the LRV's TV camera showing the ALSEP deployment site. The audio is a Mission Control track that has both the air-to-ground conversations plus the Flight Director loop where you can hear the flight controllers discussing how Cernan and Schmitt have fallen behind schedule and the potential effect on future EVA activities:

By 121:25 GET, Cernan and Schmitt had finished deploying the ALSEP and had also taken a hammered-in deep core sample of the lunar regolith. They had already been on the surface for about four hours - nearly twice as long as Armstrong and Aldrin walked on Apollo 11 - and there was so much more to come.

The remaining major activity for EVA-1 was a trip to the mission's Geology Station 1 at Steno Crater, about two kilometers away. During their traverse they deployed some of the aforementioned explosive charges for the geophone experiment, gathered samples, and took photographs.

On the return to Challenger, Cernan and Schmitt also deployed the Surface Electrical Properties Experiment, or SEP. SEP transmitted a series of electrical impulses through the lunar surface to be received by an antenna on the LRV at various locations and distances throughout the surface journeys in the remaining EVAs 2 and 3.

Challenger's crew returned to their lunar home and ended their first EVA at 123:13:42 - 2:06AM, December 12, 1972. Mission Control would have work to do while they were resting as Cernan's temporary repair to the LRV's fender didn't last. Without a solution, the dust level driving would be intolerable and put the EVAs for the next two days at risk.

In closing, I'd like to return to earlier in the EVA at 118:21 as Cernan and Schmitt were raising the American Flag at Taurus-Littrow. As I mentioned in the opening, one of the Apollo 11 flags had hung in Mission Control for Apollos 12-16. This flag was returned to the Moon aboard Apollo 17 and Challenger and is the flag that Cernan and Schmitt placed there. The two also had a second flag with them, which would be returned to Mission Control to replace the one returned to the lunar surface.

118:23:51 Cernan: Houston... 
118:23:52 Schmitt: That's beautiful. 
118:23:53 Cernan: ...this has got to be one of the most proud moments of my life. I guarantee you. [Pause] [To Jack] Why don't you get a close-in one and we'll trade cameras. 
118:24:06 Schmitt: Houston, I don't know how many of you are aware of this, but this flag has flown in the MOCR [Mission Operations Control Room at the Johnson Space Center in Houston] since Apollo 11. And we very proudly deploy it on the Moon, to stay for as long as it can, in honor of all those people who have worked so hard to put us here and to put every other crew here and to make the country, United States, and mankind, something different than it was. 
118:24:51 Parker: Roger, 17. And presuming to speak in behalf of some of those that work on the MOCR, we thank you very much.
Jack Schmitt, our flag, the lunar surface, and our home.
In my opinion, one of the greatest photographs of Apollo,
and one of the greatest ever taken, period.
Gene Cernan salutes Old Glory at Taurus-Littrow
While it wasn't the end of EVA-1, I chose to tell the story of placing the flag last because it truly is a lasting symbol of the American exceptionalism that sent twelve of its own to the surface of the Moon. Why? Well, thanks to photographs taken by the Lunar Reconnaissance Orbiter during the past several years of the Apollo 17 landing site we know one thing:

The flag that returned to the Moon still casts a shadow, which means it still flies.

And fly it shall, until someone removes it or it is knocked down by a meteor impact. Forever.

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