Apollo 15: The Complete Descent

[00:00:03][music] [music] >> The final three missions of the Apollo [music] lunar program focused on scientific goals. And to facilitate this aim, there were significant upgrades to the equipment.

[00:00:32]The stay on the surface was increased to three days. Suits were more flexible, and most notably, a remarkable electric car was carried to the moon folded into a spare bay in the lander.

[00:00:43]>> Hey, when he hits the craters and starts bouncing is when he gets his rooster tail.

[00:00:48]>> Apollo 15 was the first of these advanced missions, and it was sent to explore [music] a spectacularly beautiful plain at the eastern rim of Mare Imbrium.

[00:01:01]Sited near the crater Hadley C, the plain was bounded by mountains and a winding [music] channel Hadley Rille.

[00:01:09]This remarkable feature had been carved by flowing lava more than 3 billion years ago.

[00:01:16]The crew of the Apollo 15 lunar module Falcon was mission commander David Scott and lunar module pilot Jim Irwin.

[00:01:24]Two aspects of their descent to the lunar surface were different from previous [music] missions.

[00:01:30]To clear the mountains to the east, they flew a steeper approach profile of about 25°.

[00:01:36]Also, the [music] capability of the main engine had been increased by extending its nozzle, leaving only about 25 cm clearance [music] to smooth ground.

[00:01:46]The crew were keen to stop the engine whilst still airborne to prevent the nozzle becoming blocked by an uneven surface.

[00:01:53]A cue from probes fitted beneath the footpads would signal when to shut down the engine.

[00:02:00]Falcon orbited the moon in an east-to-west direction [music] with a low point or perilune 500 km east of the landing site and an altitude of about 53,000 ft, just [music] over 16 km.

[00:02:15]This was the point for powered descent initiation or PDI when the main engine would be ignited.

[00:02:24]At this moment, [music] the burn was being controlled by program 63 in the computer.

[00:02:29]P63 was one of three programs that handled the descent.

[00:02:34]This was the braking phase and it would last about 9 minutes during which the crew would not see the ground.

[00:02:42]P64 handled the approach phase and would rotate the spacecraft forward so that the crew could see where it was taking them.

[00:02:48]A clever onboard system would allow the commander to redesignate the landing target if necessary. [music] Once the lunar module had descended to an altitude of about 500 ft, [music] Scott selected program 66, effectively inserting himself into the control loop.

[00:03:05]This allowed him to guide the spacecraft helicopter-like to a smooth patch for touchdown.

[00:03:11]>> [music] >> Altitude >> 30 seconds now until ignition.

[00:03:36]>> We have guidance.

[00:03:38]>> I for ullage.

[00:03:39]>> Aiming by for ullage.

[00:03:51]>> 10 seconds.

[00:03:54]>> LH, go for the pro.

[00:03:57]Pro going.

[00:04:03]Auto ignition.

[00:04:07]11% the override is on.

[00:04:22]>> The LEM engine is currently at uh minimum thrust. I'll be throttling up shortly.

[00:04:28]>> Throttle up.

[00:04:33]G&C master arm off.

[00:04:35]>> G&C master arm is coming off.

[00:04:37]Lights are off.

[00:04:39]Looks stable.

[00:04:43]H-stops looking a little uh higher than normal.

[00:04:46]>> Okay.

[00:04:47]>> A little higher than normal.

[00:04:59]>> Guidance officer says we've got good thrust, 9920.

[00:05:02]>> Copy.

[00:05:04]H-stops about 20 high.

[00:05:06]>> Okay.

[00:05:09]>> Fuel is a little low, oxidizer's a little high.

[00:05:15]>> Falcon, Houston, A169 -02800.

[00:05:28]>> Roger, -2 -02800, standing by for the enter.

[00:05:33]>> Here, go for enter.

[00:05:37]>> Go for enter.

[00:05:58]>> Falcon, Houston, you're go at 2 minutes.

[00:06:03]>> All right, they're go at 2.

[00:06:05]Things and mags compare.

[00:06:07]>> We're showing an altitude of about 46,000 ft now.

[00:06:10]>> About 2% low on fuel.

[00:06:13]>> Okay.

[00:06:13]>> And one.

[00:06:24]>> They crew updated their um uh guidance systems uh targeting. Uh it was uh tending to steer them about uh 2,800 ft downrange.

[00:06:34]>> H dot's 4 high.

[00:06:37]>> Falcon, Houston, we're happy with your fuel.

[00:06:43]>> Okay, it's nice to hear.

[00:06:59]Hey, 3 minutes joined to zero.

[00:07:03]Altitude's good. H dot's right on, Dave.

[00:07:06]>> Good.

[00:07:07]>> Fuel reads 2% low.

[00:07:09]And Houston's happy with us.

[00:07:11]>> Falcon, Houston, you're go at 3.

[00:07:16]>> Roger, go at 3.

[00:07:19]>> Altitude now about 42,000 ft. Uh our velocity down to about 3,900 ft per second.

[00:07:25]>> 3,400 delta H.

[00:07:32]Velocity light is out. Delta H looks good up here. Houston, what do you think?

[00:07:36]>> Falcon, Houston, we agree with delta H except that's the landing radar data coming in, and uh Scott just reported they're accepting that data.

[00:07:48]>> And Houston, ED batteries checked.

[00:07:51]>> Copy.

[00:08:01]>> 4 minutes.

[00:08:03]Altitude's 2,000 high. Okay, about 3 low.

[00:08:08]One oxidizer looking good.

[00:08:10]M1%. Eight things in ice look good.

[00:08:20]>> The primary guidance system thinks it's about 3,000 ft lower than it is. The uh radar should correct that.

[00:08:32]>> 4:30.

[00:08:33]Altitude's 4,000 high. H dot's right on.

[00:08:36]One oxidizer good.

[00:08:38]Hey.

[00:08:40]Altitude H is 2,000.

[00:08:58]>> We're about 5 minutes into the uh maneuver now.

[00:09:01]And Glenn Loney uh taking a status. Go all the way.

[00:09:04]>> All right.

[00:09:05]Stop.

[00:09:06]About 9 high.

[00:09:08]Okay, Houston, you're go at >> 5, and your fuel quantity looks good here.

[00:09:15]>> Okay, understand. Go at 5.

[00:09:31]All right.

[00:09:34]Altitude's 3,000 high. H dot 10 high.

[00:09:38]One oxidizer good.

[00:09:40]>> Okay.

[00:09:42]>> We're still looking good. Velocity down now at 2,400 ft per second.

[00:10:03]Glen Lunney making another status as we >> look good. Bye.

[00:10:06]>> Okay. Bye.

[00:10:07]>> Oxidizers are good.

[00:10:09]>> And the delta H is looking pretty good.

[00:10:16]>> Falcon, Houston, you're go at 6.

[00:10:20]>> Roger, go at 6.

[00:10:26]>> We're about 3 minutes now from the approach phase. Altitude about 2,500 ft.

[00:10:30]25,000 ft correction.

[00:10:33]>> Altitude 1,000 high.

[00:10:35]>> H dot about 4 high.

[00:10:37]>> X axis override done.

[00:10:46]>> Falcon, Houston, throttle down 7 + 2 3.

[00:10:52]>> Roger, 7 + 2 3.

[00:11:02]>> 7 minutes.

[00:11:03]1,000 high. Pitch matches just about on.

[00:11:08]Oxidizers run about 1% low.

[00:11:18]>> Coming up on throttle down in about 3 seconds. The guidance system will back off on the thrust to about 50% 57%.

[00:11:25]>> 52.

[00:11:29]>> And the crew confirmed throttle down right on time.

[00:11:33]>> 30 over All of those are good. Okay. Check the manual.

[00:11:45]No flags. Looks good.

[00:11:58]>> Falcon Houston, descent one.

[00:12:03]>> Roger, descent one and looks like P64 at 923.

[00:12:08]>> Roger.

[00:12:14]>> P64 is the final approach phase where the lunar module pitches up for the astronauts first good look at the landing site.

[00:12:24]Altitude now about 16,000 ft.

[00:12:27]>> 30 ft.

[00:12:31]Mark.

[00:12:33]Good.

[00:12:48]>> Guidance says it looks as if we may be coming in a little bit south of the site. Everything looks good, however.

[00:13:06]Falcon Houston, we expect you may be a little south of the site.

[00:13:09]>> up on 8,000 ft.

[00:13:13]Okay.

[00:13:20]>> Coming up on pitch over.

[00:13:21]>> State.

[00:13:24]P64. State.

[00:13:26]Have LPD.

[00:13:28]LPD.

[00:13:30]Coming right.

[00:13:32]40 5,000 ft 39 39 38 39 4,000 ft 40 41 45 47 52 3,000 ft 52 52 51 50 47 47 2,000 ft 42 Okay, got a good spot at 42 43 900 ft Falcon Houston you're go for landing.

[00:14:24]45 Falcon go for landing.

[00:14:27]44 45 1,000 ft 45 900 45 800 45 700 46 600 48 500 49 minus 17 minus 15 400 at minus 14 FT66 okay 300 ft minus 11 minus 11 250 minus 11 9% fuel at 200 minus 11 150 minus seven minus six 120 feet minus six >> They have got some dust.

[00:15:29]>> minus five 100 feet at five 9% fuel minus five 80 at five minus three 60 at three 50 at three cross pointers look good 40 at three 30 three 25 two 7% fuel 20 at one 15 at one minus one minus one 6% fuel 10 feet minus one 8 feet minus one contact there Okay, Houston is in the Falcon is on the plane at Hadley.

[00:16:28]>> Roger Roger Falcon >> I deny that we had contact.

[00:16:48]>> That was a jubilant Dave Scott reporting Apollo 15 on the plane at Hadley.

[00:16:56]>> ACF looks good.

[00:17:03]Okay.

[00:17:04]They wiggle their toes Feel it steady.

[00:17:10]Did you get the landing radar open?

[00:17:12]>> Yep.

[00:17:12]>> Okay.

[00:17:19]Stand and by for T1.

[00:17:21]>> All right.

[00:17:24]>> Just stand by.

[00:17:29]>> Everything is good on board.

[00:17:35]>> Falcon Houston, you're stay T1.

[00:17:40]>> Roger, stay for T1.

[00:17:44]Hey.

[00:17:46]Hey, what's going on with the little checklist?