ПІЕ YE-8-5 LUNAR SAMPLE RETURN SERIES: 1969-1976 Campaign objectives

In late 1968 and early 1969 it became apparent to the Soviet Union that American astronauts might very well reach the Moon before Russian cosmonauts. Anxious to ensure that a Soviet mission was first to return lunar soil to Earth, NPO-Lavochkin hurriedly modified the Ye-8 spacecraft for a sample return mission. The lunar rover variant of this spacecraft was well advanced in design by the end of 1968. and could readily be modified simply by replacing the payload of the lander. Even although it would have scientific merit, the sample return mission had a far greater significance than being just another task for the Ye-8. The robotic sample return mission became the means to upstage Apollo by returning a sample to Earth before the Americans could do so. The fact that these complex spacecraft could be designed and built so readily, and ultimately work so well, is amazing in hindsight. It would seem to be a Russian characteristic to ”just do if to dismiss the hardship, use whatever you have at hand, and fix things up on the fly during and after build.

The modification of the Ye-8 lunar rover spacecraft to the Ye-8-5 for the sample return mission faced daunting problems, not the least of which were mass limitations on the return vehicle, lifting off from the Moon and navigating back to Earth. It was originally believed that the return vehicle would require the same complex avionics as any interplanetary spacecraft, to enable its position to be determined and to make midcourse correction maneuvers. The avionics necessary to meet these requirements far exceeded the available mass. However. D. Ye. Okhotsimskiy, a scientist at the Institute of Applied Mathematics, found a small set of flight trajectories for launches from the surface of the Moon that did not require midcourse corrections. In essence, the large gravitational influence of the Earth at lunar distance could, under certain conditions, assure an Earth return. These trajectories were limited to specific points on the Moon, varying within a general locus with the time of year, and required the lander to set dow n within 10 km of its target and the lunar liftoff for a direct ascent to occur at a precise moment. Accurate knowledge of the lunar gravitation field was also required, but this information had already been determined by the Luna 10, 11. 12 and 14 orbitcr missions.

Spacecraft launched
First spacecraft: Mission Type: Country! Builder: Launch Vehicle: Launch Date! t ime: Outcome:	Ye-8-5 No.402 Lunar Sample Return USSR NPO-Lavochkin Proton-K June 14, 1969 at 04:00:47 UT (Baikonur) Fourth stage failed to ignite.
Second spacecraft: Mission type: Country і Builder: Launch Vehicle: Launch Date; Time: Lunar Orbit Insertion: Lunar landing: Outcome:	Luna 15 (Yc-8-5 No.401) Lunar Sample Return USSR NPO-Lavochkin Proton-K July 13, 1969 at 02:54:42 UT (Baikonur) July 17, 1969 at 10:00 UT July 2L 1969 at 15:51 UT Crashed.
Third spacecraft: Mission type: Coun try; Builder: Launch Vehicle: Launch Date: Time: Outcome:	Ye-8-5 No.403 (Cosmos 300) Lunar Sample Return USSR NPO-Lavochkin Proton-K September 23, 1969 at 14:07:36 UT (Baikonur) Fourth stage failure, stranded in Karth orbit.
Fourth spacecraft: Mission Type: Country! Builder: Launch Vehicle: Launch Date; Time: Outcome:	Ye-8-5 No.404 (Cosmos 305) Lunar Sample Return lJSSR NPO-Lavochkin Proton-K October 22, 1969 at 14:09:59 UT (Baikonur) Fourth stage misfire, stranded in Earth orbit.
Fifth spacecraft: Mission Type: Country і Builder: Launch Vehicle: Launch Date ‘: 7 ime: Outcome:	Ye-8-5 No.405 Lunar Sample Return USSR NPO-Lavochkin Proton-K February 6. 1970 at 04:16:06 UT (Baikonur) Second stage premature shutdown.
Sixth spacecraft: Mission Type: Country! Builder: Launch Vehicle: Launch Date! Time: Lunar Orbit Insertion: Lunar landing: Ascent Stage Liftoff: Earth Return: Outcome:	Luna 16 (Yc-8-5 No.406) Lunar Sample Return lJSSR NPO-Lavochkin Proton-K September 12, 1970 at 13:25:53 UT (Baikonur) September 17, 1970 September 20. 1970 at 05:18 UT September 21, 1970 at 07:43 UT September 24, 1970 at 03:26 UT Success.

Seventh spacecraft:	Luna 18 (Ye-8-5 No.407)
Mission Type:	Lunar Sample Return
Country і Builder:	USSR, NPO-La vochkin
Launch Vehicle:	Proton-K
Launch Date: Time:	September 2, 1971 at 13:40:40 UT (Baikonur)
Lunar Orbit Insert і on:	September 7, 1971
Lunar Landing:	September 1U 1971 at 07:48 UT
Outcome:	Failure at landing.
Highth spacecraft:	Luna 20 (Ye-8-5 No.408)
Mission Type:	Lunar Sample Return
Country! Builder:	USSR/NPO-Lavochkin
Launch Vehicle:	Proton-K
Launch Dale ‘: I ime:	February 14, 1972 at 03:27:59 UT (Baikonur)
Lunar Orbit Insertion:	February 18, 1972
Lunar Landing:	February 21, 1972 at 19:19 UT
Ascent Stage Liftoff:	February 22, 1972 at 22:58 UT
Earth Return:	February 25, 1972 at 19:19 UT
Outcome:	Success.
Ninth spacecraft:	Luna 23 (Yc-8-5M No.410)
Mission Type:	Lunar Sample Return
Country j Builder:	USSR NPO-Lavoch kin
Launch Vehicle:	Proton-K
Launch Date; Time:	October 28, 1974 at 14:30:32 UT (Baikonur)
Lunar Orbit Insertion:	November 2, 1974
Lunar landing:	November 6, 1974
Mission End:	November 9, 1974
Outcome:	Damaged on landing, no return attempted.
Tenth spacecraft:	Ye-8-5M No.412
Mission Type:	Lunar Sample Return
Country і Builder:	USSR, NPO-Lavochkin
Launch Vehicle:	Proton-K
Launch Date: Time:	October 16, 1975 at 04:04:56 UT (Baikonur)
Outcome:	Fourth stage failure.
Fle venth spacecra ft:	Luna 24 (Ye-8-5M N0.413)
Mission Type:	Lunar Sample Return
Country і Builder:	l JSSR/NPO-Lavoch к І n
Launch Vehicle:	Proton-К
Launch Dale; Time:	August 9* 1976 at 15:04:12 UT (Baikonur)
Lunar Orbit Insertion:	August 14, 1976
Lunar Landing:	August 18, 1976 at 06:36 UT
Ascent Stage Liftoff:	August 19, 1976 at 05:25 UT
Earth Return:	August 22, 1976 at 17:35 UT
Outcome:	Success.

Figure 11.20 Luna sample return sequence (courtesy NPO-Lavochkin and Space Travel Encyclopedia)’. 1. Launch; 2. Parking; 3. Translunar injection burn orbit; 4. Translunar flight; 5. Trajectory correction maneuver; 6. Lunar orbit injection bum; 7. Lunar orbit; 8. Maneuvers to final orbit; 9. Descent sequence; 10. Ascent from the lunar surface; 11. Free-return trajectory to Earth; 12. Separation from return vehicle and entry.

These passive return trajectories simplified the ascent vehicle enormously. Only a single burn of the ascent vehicle was required. No active navigation was necessary, and no midcourse maneuvers were required. The only problem with a passive return was the very large error ellipse on arrival at Earth, which would make recovering the small capsule impraclically difficult. This problem was solved by using a low-mass meter wave radio beacon on the ascent vehicle so that radio tracking would be able to determine its actual trajectory, supplemented by optical observations from Earth during the latter half of its flight. In addition, the return capsule would have its own radio beacon to assist in recovery operations.

Even with these ingenious solutions, the engineers could not trim the design mass of the Ye-8-5 below 5,880 kg. At that time the most that the Proton-К could send to the Moon was 5,550 kg. However, Babakin managed to cajole the Proton maker into providing sufficient additional mass capability to launch his sample return spacecraft to the Moon. This was accomplished without major changes to the launch vehicle.

Spacecraft;

Lander stage:

The lander stage was essentially the same as designed for the rover mission and its mission profile through to lunar landing was identical. The only differences were the attachment of a surface sampling system and, for the first eight spacecraft, a pair of television cameras for stereo imaging of the sampling site and floodlights for night landings. The rover and ramps were replaced by a toroidal pressurized compartment which held the instruments and avionics for surface operations. The ascent stage was mounted on top, with the entire lander and toroidal compartment acting as its launch pad.

Figure 11.21 Luna 16 spacecraft diagram (from Ball el al.) and during lest at Lavochkin.

The ascent stage was powered by a silver-zinc 14 amp-hour battery, and the return capsule by a 4.8 amp-hour battery. Lander communications were provided at 922 and 768 MHz, with backups at 115 and 183 MHz. The ascent stage communicated at 101.965 and 183.537 MIIz. The return capsule had beacons at 121.5 and 114.167 MHz for radio tracking.

The sampling system for the Ye-8-5 consisted of an upright 90 cm long boom arm capable of two degrees of freedom, with a drill at its end for surface sampling. Three movements were required to place the drill on the surface through a 100 degree arc of swing, and then another three to transfer the sample to the ascent stage. From the stowed position it first swung itself vertical, then rotated in azimuth to line up on the selected sample site before swinging down onto the surface. A movement in azimuth with the head on the ground might be used to clear a small area to improve drilling. This sequence was reversed to transfer the sample to the return capsule of the ascent stage. Mounted at the end of the boom was a cylindrical container 90 mm diameter and 290 mm long for a hollow rotary/percussion drill. The drill bit had a diameter of 26 mm and was 417 mm long. Its cutter was a crown with sharp teeth. The drill was equipped with different coring mechanisms for hard coring and for loose coring. At a speed of

Figure 11.22 Lu^a 16 and Luna 20 spacecraft: 1. Return vehicle; 2. Earth entry system straps; 3. Return vehicle antennas; 4. Return vehicle instrument compartment; 5. Return vehicle fuel tanks; 6. Imaging system; 7. Lander instrument compartment; 8. Soil sampler boom; 9. Soil sampler; 10. Lander propulsion system; 11. Landing legs; 12. Footpad; 13. Lander fuel tanks; 14. Attitude control jets; 15. Return system engines; 16. Low-gain antenna.

500 rpm, it required 30 minutes to fill the entire core length of 38 cm. The drill was both insulated and hermetically sealed, and to enable the mechanism to be lubricated using oil vapor it was not opened until just before use. Some parts used a lubricant designed to reduce friction in a vacuum. A standby motor was provided as a contingency to overcome obstacles encountered during drilling. The whole device weighed 13.6 kg.

An improved drill system tvas provided for the Ye-8-5M version, which had a rail mounted deployment mechanism. This drill was capable of penetrating to a depth of

2.5 meters and preserving the stratigraphy, but it could not be articulated to select a sampling site. It used an elevator mechanism rather than the articulated boom arm to transfer the sample to the return capsule.

Figure 11.23 Luna 16 and Luna 20 sampling system (from Space Travel Encyclopedia): 1. Entry capsule; 2. Stowed position of the drill arm; 3. Deployed position of the drill arm; 4. Soil container; S. Soil sample with drill bit; 6. Locking cover; 7. Hermetically sealing sample container cover; 8. Spring; 9. Drill unit container; 10. Drill motor; 11. Drill motor transmission; 12. Drill head.

Ascent stage:

The ascent stage was a smaller, vertically mounted open structure composed of a pressurized cylindrical avionics compartment above three spherical propellant tanks and the rocket engine. This was the same engine as used on the lander, but was not throttled. Four vernier engines were attached outboard of the propellant tanks. There were perpendicular antennas mounted radially at 90 degree intervals near the top of the avionics compartment. The spherical return capsule was held in place on top by deployable straps. Including the return capsule, the ascent stage was 2 meters tall. It weighed 245 kg dry and 520 kg with propellant. The KRD-61 Isayev engine burned nitric acid and UDMH and produced a thrust of 18.8 kN for 53 seconds to impart a velocity of 2.6 to 2.7 km/s, which was enough to escape from the Moon on a direct ascent trajectory.

Return capsule:

The return capsule was a 50 cm sphere covered with ablative material for entry at a speed of about 11 km/s and a peak deceleration load of 315 G. It had three internal sections. The upper section contained the parachutes (a 1.5 square meter drogue and a 10 square meter main) and beacon antennas, the middle section contained the lunar sample, and the base had the heavy equipment including batteries and transmitters.

on entry.

Luna 15 launch mass: 5,667 kg

Luna 16 launch mass: 5,727 kg

Luna 18 launch mass: 5,750 kg

Luna 20 launch mass: 5,750 kg

Lima 23 launch mass: 5,795 kg

Luna 24 launch mass: 5,795 kg

4,800 kg (Luna 24)

1,880 kg

520 kg (515 kg for Luna 23 and 24) 35 kg (34 kg for Luna 23 and 24)

Payload:

1. Stereo panoramic imaging system with lamps (deleted on Luna 23 and 24)

2. Remote arm for sample collection (improved drill on Luna 23 and 24)

3. Radiation detectors

4. Temperature sensor inside capsule

The stereo imaging system had two 300 x 6,000 panoramic scan cameras of the type used on the earlier Yc-6 landers and Lunokhod rovers. Mounted on the lander just below the level of the ascent stage on the same side as the sampling system, they were spaced 50 cm apart, angled at 50 degrees to the vertical, and gave a field of view of 30 degrees. The orientation of the lander was determined by measuring the position of Earth in a panoramic image. Stereo images were taken of the surface between the
two landing legs to select the position to be sampled. They also imaged sampling and drilling operations, For the Luna 23 and 24 sample ret urn missions the earner as and lamps were deleted.

Mission description:

Only six of the eleven spacecraft in this series were launched successfully. Of these, three succeeded in returning lunar samples to Earth.

The first attempt

The first launch (Ye-8-5 No.402) was attempted on June 14, 1969. one month prior to the Apollo 11 launch date, but the Block D failed to ignite for its first burn and the payload re-entered over the Pacific Ocean.

Luna 15

The second spacecraft in this series was successfully launched on July 13, 1969, just 3 days before Apollo 11, and the Soviets announced that Luna 15 was to land on the Moon on July 19, one day ahead of the Americans, with the objective of returning something to Earth. At 10:00 UT on July 17 it entered a 240 x 870 km lunar orbit inclined at 126 degrees. ‘This orbit was much higher than intended, so the next day it was trimmed to 94 x 220 km. Another trim a day later yielded an orbit 85 x 221 km. Ideally the orbit should have been near-circular at about 100 km, but the Soviets had underestimated the effect of the lunar in a scons and they were also suffering attitude control problems. Meanwhile. Apollo 11 had arrived and entered an equatorial orbit The drama was palpable. In Russia its nature was clear, but in America the ultimate purpose of Luna 15 was mysterious and opinions ranged from the suspicious to the sublime to the ridiculous. Apollo 8 astronaut Frank Borman, just back from a visit to the Soviet Union, appealed for information and the Academy of Sciences supplied orbit data, operational frequencies, and assurances that Luna 15 would not endanger the Apollo 11 mission.

On July 20. after several more orbit changes, Luna 15 began its descent sequence during its 39th orbit by lowering its perilune to 16 km above the landing site in the Sea of Crises. The intention was to land just 2 hours before Apollo 11 landed further west in the Sea of Tranquility. But when controllers saw the radar data from the first perilune pass they became concerned. The one and only target appeared uneven and potentially dangerous. It must have been with the utmost reluctance and dismay that the decision was taken to postpone the landing to test the radar and perform further observations. As a result of this delay, not only was there now’ no chance of landing ahead of the Americans, the nature of the return trajectory would make it impossible to get a sample back first. All of this w as unknown to an anxious world, wondering wrhat stunt Luna 15 was going to pull in order to upstage Apollo 11. Eighteen hours later, on its 52nd orbit, Luna 15 w*as commanded to land at 15:46:43 UT on July 21. after Armstrong and Aidrin had already walked on the Moon. The descent maneuver failed and. for reasons still to be explained, the transmission ceased 4 minutes after the de-orbit burn started. It erashed at 17 N 60 H, about 800 km east of Tranquility Base. Jodrell Bank flashed notification to the Americans that Luna 15 had impacted at a velocity of 480 m/s just as Apollo 11 ‘s lunar module was preparing to leave the Moon. The Soviets reported that Luna 15 had ’"reached the lunar surface in a preset area" but remained silent on its true mission and there was no propaganda victory.