RUSSIA’S LAST CHALLENGE

With the failure of the N-l, Russian hopes of mounting an effective challenge to Apollo were sinking fast. The first sample return mission in June had failed and now the second N-l. Now the gambler had only one card left to play. The second Ye-8-5 was prepared and hustled to the pad in early July. The scientists may well have expected that the Proton booster would let them down again, and it was probably to their surprise that it did not. As if to scorn the earlier run of failures, it hurtled Luna 15 moonwards at 02: 54 gmt on l3th July 1969. As had been the case the previous December, the celestial mechanics of the respective launch windows gave the Russians a slight advantage and enabled a launch ahead of Apollo. Once the launch was successful, preparations were put in train for a triumphant parade through Moscow, probably for the 26th or 27th July. An armoured car, covered in the Soviet flag and bedecked with flowers, would bring the rock samples from Vnukuvo Airport into Moscow, through Red Square, past the west gate of the Kremlin and on to the Vernadsky Institute where they would be displayed to a frenzy of the world’s press before being brought inside for analysis [7].

The Ye-8-5

Luna 15 was the first of the third-generation Ye-8 spacecraft to succeed in leaving Earth orbit. Because it was pushing the performance of the Proton rocket to the limit, it took a fairly lengthy trajectory to the moon, in the order of 103 hours, much longer than previous moon probes. It was a tense outward journey, for telemetry indicated that the ascent stage fuel tank was overheating, threatening an explosion. Only when they turned the tank away from the sun did temperatures stabilize.

The mission profile was for a four-day coast to the moon, followed by entry into a circular 100 km lunar orbit. After a day, the orbit would be altered to bring the low point down to 16 km, right over the intended landing point. After another day, the inclination would be adjusted – probably a small manoeuvre – to ensure the lander came in over its landing site at the right angle. Sixteen hours later, after 80 hours in lunar orbit, an engine dead-stop manoeuvre would take place, after which Luna 15 would be right over the landing spot and then make a gentle final descent. After touchdown, the 90 cm long drill arm would engage. Cameras would film the scene for television. After drilling down, the arm would pop the samples back in the ascent stage. After a day on the moon, at 20:54 gmt on 21st July, Luna 15 would blast Earthward for a three-day coast to Earth. Although Luna 15 would leave the moon three hours after the American lunar module, it would fly direct back to Earth. The Americans would still face several difficult hours of rendezvous manoeuvres, transfer­ring equipment, jettisoning the LM and then blasting out of lunar orbit, while all this time Luna 15 would speed Earthward. The Russians still faced a problem, for the return trajectory still took longer than Apollo 11 and would not get the moonrock back to Earth until 20: 54 on the 24th, more than two hours after Apollo would land in the Pacific. Presumably, creative news management would have been called in to present a suitable account of the return to Earth.

Appointed to direct the mission was Georgi Tyulin. Tyulin had played an important role in the early days of the Soviet space programme. A military man, he had directed the Red Army’s Katyusha rocket units in the war. In 1945, he was one of only four people to go to Cuxhaven, Germany, on a military delegation to watch the British fire a captured German V-2 over the North Sea, in the distinguished company of Sergei Korolev, Yuri Pobomonotsev and Valentin Glushko. He had masterminded the transfer east of the V-2 equipment to the launch base at Kapustin Yar on the Volga. Since then he had worked in military institutes, developing launch ranges and tracking systems, rising to lieutenant general.

Luna 15 produced the expected level of consternation in the West. Most observers thought Luna 15 could be a moon sample return mission, but doubted whether the USSR had the technological ability to pull it off. A typical view was this in the British Daily Telegraph.

While the moonshot is regarded as a last-minute attempt to detract from the American effort, it is not thought the Russians can land and bring back samples. The technical complexities are thought to be too great.

But as the Apollo 11 launching drew near – it was now only three days away – one absurd idea rivalled another. Luna 15 wouldjam Apollo 11’s frequencies. It was there to ‘spy’ on Apollo 11 – like the Russian trawlers during NATO naval exercises, presumably. It was there to report back on how the Americans did it. It was a rescue craft to bring back Armstrong and Aldrin if they got stranded. With Apollo 11 already on its way to the moon, excitement about the forthcoming moon landing reached feverish levels. Scientists, experts, engineers, anyone short of a clairvoyant was called in to the television studios to comment on every change of path or signal. Cosmonaut Georgi Beregovoi, who could always be counted on to be indiscreet, let it be known that ‘Luna 15 may try to take samples of lunar soil or it may try to solve the problem of a return from the moon’s surface.’

By 15th July, Luna 15 was exactly halfway to the moon. Jodrell Bank – invariably tracking it – said it was on a slow course to save fuel. There was more speculation as to the ulterior motives of choosing a slow course to the moon to save fuel. Sinister implications were read into the tiniest details.

The Ye-8-5 return cabin

At 10:00 on 17th July, Luna 15 braked into lunar orbit, but entered a much wider orbit than the 100 km circular path planned, one ranging instead from 240 km to 870 km. In most subsequent official accounts of the mission, the parameters of the initial orbit were not published, although the subsequent ones were. This path was far more eccentric than what had been intended, suggesting a considerable underburn at the point of insertion into lunar orbit, one in the order of 700 m/sec rather than the 810 to 820 m/sec of all its successors [8]. There was intense radio traffic from the probe, which beamed back loud signals within 20 min of coming out from behind the moon. Jodrell Bank reported back that its signals were of an entirely new type, never heard before.

Although Moscow news sources reported that everything was normal, in fact ground control was engaged in a desperate struggle to measure the unplanned orbit and find a way to get Luna 15 into its intended path. In other circumstances, this might not have presented problems, but Apollo 11’s well-publicized landing schedule was uppermost in people’s minds. On 18th July, on or around the 10th orbit, ground controllers did manage to bring Luna 15 out of its highly elliptical orbit into one of 220 km by 94 km. This was still more eccentric than the 100 km orbit intended, but the perigee was close enough. The Russians had agreed to relay details of its orbit to the Americans who were worried about its proximity to Apollo 11, and they used Apollo 8 commander Frank Borman as an intermediary. Interestingly, Mstislav Keldysh told him that Luna 15 would remain in this orbit for two days (which was what had indeed been originally intended at orbital insertion), giving an orbital period of 2 hr 35 min

(the one achieved after major orbital adjustment), but left it to NASA to calculate the altitude. Even today, there is a lack of a commonly agreed set of tables for Luna 15.

Manoeuvres of Luna 15

17 July Lunar orbit insertion: 240-870km, 2hr 46min, 126°

18 July First course correction, orbit 10: 220km by 94km, 2hr 35min, 126°

19 July Second course correction, orbit 25: 221 km by 85 km, 2hr 3.5min, 126°

20 July Third course correction, orbit 39: 85 km by 16 km, 1 hr 54min, 127°

21 July Descent, orbit 52: 16: 50 loss of signal

On 19th July, tension rose. Apollo 11, with the Apollo astronauts on board, had now slipped into lunar orbit. The world’s focus shifted to the brave men on Apollo 11 carrying out their final checks before descending to the surface of the moon. Now on its 39th orbit, Luna 15 fired its motor behind the moon to achieve the pre-landing perigee of 16 km. This was its final orbit, for at 16 km there was barely clearance over the mountain tops and was about as low as an orbit could go. The probe could only be preparing to land. The perilune was known to be over the eastern edge of the moon, not far from the Apollo landing site in the Sea of Tranquillity, but farther to the northeast, over a remarkably circular mare called the Sea of Crises. The Luna 15 mission was back on course.

13	02:54 Launch
16		13:32 Launch
17	10: 00 Lunar orbit insertion
18	13: 00 Apolune lowered to 220 km
19	13: 08 Perilune to 85 km	17: 22 Lunar orbit insertion
20	14: 16 Final orbit, perilune 16 km
	[19: 00 Original scheduled landing]	20: 19 Landing on moon
21	15: 50 Loss of signal on landing
	[20: 54 Original scheduled lunar liftoff]	17: 54 Take-off from the moon
22		04: 57 Leave lunar orbit
23
24	[20: 54 Original scheduled landing]	16: 50 Splashdown

Luna 15 and Apollo 11: timelines Luna 15

Apollo 11

Note: times are gmt.

In reality, Luna 15 was now in fresh trouble. When the engineers turned the radar on at the low point of the orbit, 16 km, to verify the landing site, they got problematic readings. Although the Sea of Crises has a flat topography – some of the moon’s flattest – the radar instead indicated quite an uneven surface. Luna 15 was scheduled to land at 19: 00 that evening, the 20th, only an hour before Apollo 11’s Eagle, coming into the Sea of Crises from the north. Tyulin decided to delay the landing for 18 hours in order to retest the radar, try and get a clearer picture of the terrain and calculate the precise moment for retrofire as carefully as possible. This must have been a difficult decision for, by doing so, there was no way that Luna 15 could be back on Earth before Apollo 11. This was the first time that Russia had attempted a soft landing from lunar orbit (indeed, the same could be said for Apollo 11’s Eagle). The retrofire point had to be precisely set in altitude and location: 16 km above the surface, not more than 19 km, not less than 13 km, so as to match the capacity of the engine.

Few people gave much thought to Luna 15 for the next day as they listened in wonder to the descent of Neil Armstrong and Edwin Aldrin to the lunar surface, agonized through the final stages of the descent and then watched the ghostly television images of the two men exploring the lunar surface. On the early evening of 21st July, Armstrong and Aldrin stood in their lunar module going through the final checks before take-off from the moon, a manoeuvre that had never been done before. Just as they did so came a final newsflash from Jodrell Bank. It was to serve as Luna 15’s epitaph:

Signals ceased at 4.50pm this evening. They have not yet returned. The retrorockets were fired at 4.46 pm on the 52nd orbit and after burning for four minutes the craft was on or near the lunar surface. The approach velocity was 480 km/hr and it is unlikely if anything could have survived.

Jodrell Bank identified the Sea of Crises as the landing spot. The dramatic conclusion to Luna 15, just as the lunar module was about to take off, made for great television drama. Imagine, though, if Luna 15 had been able to follow its original schedule, land just before Eagle and take off just afterwards: this was a script beyond the imagination of Hollywood.

Despite his caution and giving the landing his best shot, Tyulin’s Luna 15 impacted 4min into a 6 min burn when it should have still been 3,000 m above the surface. Official explanations ventured that it hit the side of a mountain. Granted that the Sea of Crises is one of the flattest maria on the moon, this seems implausible. More likely, there was a mismatch between the low point of the orbit, 16 km and the imagined surface point (a surface reference point can be difficult to calculate when there is no natural marker, like sea level on Earth). A navigation error was most likely responsible. Another explanation is that the landing motor was late in firing [9]. American military trackers kept a close watch on Luna 15, and their analysis indicated that the Russians had difficulty controlling the pitch axis on Luna 15. Thirty-five years later, their reports strangely remained ‘top secret’.

Many, mostly unconvincing reasons were advanced by the Soviet press to explain away Luna 15. One publication even had the nerve to claim that ‘if it hadn’t happened to coincide with the dramatic Apollo lunar flight, it would hardly have received a mention at all.’ So what was Luna 15 then? Just a new moon probe. A survey ship that was highly manoeuvrable. Indeed, it had a flexibility that the American moonship did not have because it could manoeuvre freely, unlike Apollo which was stuck in narrow equatorial orbit. One wonders if the author – one ‘Pyotr Petrov’ – even believed this himself.

Following the first moon landing, the original Apollo lunar exploration programme was cut back and redirected. The Russian programme, for its part, went through a prolonged and painful reorientation before eventual cancellation. The programme of unmanned lunar exploration was the only substantial part salvaged from its pro­tracted demise. The redirection of the Soviet moon programme may be divided into several phases:

• Winding down of the L-1 Zond around-the-moon programme, 1969-70.

• Testing the LK and the LOK, 1971-2.

• Cancellation of the original N-1 moon-landing programme in 1971.

• Replacement by a revised scheme of lunar exploration, 1971-4, the N1-L3M.

• Suspension of the N-1 in 1974, with its final cancellation in 1976.