Leonard David's INSIDE OUTER SPACE

Russia’s revamping of Moon exploration is off to a rocky start – the plunge from lunar orbit of the country’s Luna-25 spacecraft, destroying itself as it crashed into the Moon’s bleak landscape.

Head of Russia’s Roscosmos, Yuri Borisov, reports that the main cause of the Luna-25’s failed mission was an engine failure. Instead of a planned propulsive nudge of 84 seconds, the engine operated for 127 seconds, more than the “required value” in readying the probe for its descent burn. This added impulse to Russia’s Luna-25 led to it crashing into the Moon, Borisov told Rossiya 24 television.

Modern Russia history

Following its August 10 liftoff, the Moon-bound Luna-25 had switched on its scientific equipment. All systems on the spacecraft were working normally, reported Roscosmos.

Spending multiple days in lunar orbit, the spacecraft was targeted to set down at the Moon’s south pole region, near the Boguslawsky crater. Two backup landing spots were also in play: southwest of Manzini Crater and south of Pentland A Crater.

Designed, built and tested by NPO Lavochkin, Luna-25 was to work on the lunar surface for at least one Earth year.

Luna-25’s sendoff from the Vostochny spaceport picked up where the former Soviet Union’s Moon-probing projects left off. It was back in 1976 that Luna-24 successfully rocketed to Earth about 170 grams of lunar topside samples.

Heralded as the first domestically produced Moon probe in modern Russia history, Luna-25’s flight was iconic in both political and scientific terms. The implications of its failure are likely to be non-trivial.

Low point

Following the Luna-25 crash, Russia quickly appointed an investigatory committee.

“We should expect an initial report in weeks. The immediate cause seems, in general, to be clear enough,” said Brian Harvey, a noted author and space historian in Ireland with a keen eye on past Soviet Union, now Russian, space exploits.

“The Luna-25 engine fired for 50 percent longer than planned,” Harvey told Inside Outer Space, making the low point in the orbit of the vehicle not the 11 miles (18 kilometers) intended, but far below surface level, a “minus” 9 miles (15 kilometers).

“The deeper causes will take more unraveling,” Harvey added. “The crash came not at the most risky point of the mission — the final stages of the descent to the surface — but during what should have been a routine firing to lower the orbit before the final descent.”

 

Unless it was purely an engine failure, Harvey added that it seems this failure is yet another instance whereby computer guidance and engine control issues in various forms have doomed soft-landings. 

Automated descents

Harvey points to the failures of Beresheet (Israel), Chandrayaan-2 (India), Hakuto-R (Japan) and the Schiaparelli lander on Mars (Europe).

“Ironically, the Soviet Union pioneered successful automated descents from lunar orbit using radar and pre-digital control and guidance,” Harvey said, the Luna-16, 17, 20, 21 and 24 missions. 

“Only China has a clean sheet in computer guidance and engine control descent from lunar orbit. For everyone else, it’s hard. Ironically too, Russian quality control has improved greatly in recent years, but people will remember this exception,” Harvey said.

Below ground level

Space expert, Bob Christy of the informative and authoritative website OrbitalFocus explains that Luna-25’s orbit was around 62 miles (100 kilometers) circular at 87 degrees inclination.

A thruster firing by the Moon-circling craft was set to lower it to 10 miles x 62 miles (16 x 100 kilometers) and the next phase would have been the landing burn to put it down on the surface from that 10 miles (16 kilometers) altitude. The inclination, he said, allowed Luna-25 to pass over the polar target area.

“The perigee-lowering burn went on for too long either through failing to shut down or through the engineers programming it wrongly,” Christy told Inside Outer Space. “It would have resulted in perigee below ground level. The time of signal loss probably marks when it hit the surface.”

As for the Luna-25 failed attempt, “Russia was probably starting from scratch in planning and executing this mission as its experienced engineers from the 1970s had long passed retirement age. It wasn’t a simple evolution of the previous lunar mission,” Christy concluded.

 

 

China’s confidence

According to Brian Harvey, the traditional reaction to a serious failure in the Russian and Soviet space program has been a punitive “heads-will-roll” approach and less funding. 

This time, though, that is unlikely to help Russia maintain a lunar program (Luna-26, 27) to match its partner China’s (Chang’e-6, 7, 8), Harvey said. 

“Chinese lunar engineers attended the Luna-25 launch at Vostochny for the first time, a short distance to travel geographically but a longer one politically and Russia must recover China’s confidence.” 

It is not known if there is a Luna-25 backup or if a replacement can be constructed, Harvey said, but waiting several years for Luna 26 will not encourage China.

Deeper causes

“Although sanctions on computer parts and a limited tracking system have been blamed for the failure, these are insufficient explanations,” said Harvey. “The Soviet Union ran a successful lunar program from 1959 to 1976 despite a sanctions wall and with limited tracking networks.”

The deeper causes of the Luna-25 failure go back to the 1990s, Harvey continued, the period of “chaos capitalism” when the whole space program almost collapsed.

“Russian space spending now lags far behind the U.S., China, Europe and even Japan,” Harvey said. Space science suffered the most, he said, exemplified by the failed Roscosmos-operated Mars 96 (sometimes called Mars-8) mission, “completed by candlelight in an unheated hanger in winter.” 

Underfunding

Apart from two successful observatories, Spektr R and Spektr RG, there have been hardly any scientific missions, Harvey said. Experience in running such complex missions is low, he said. 

Before all contact with Russia was cut off, European visitors to Moscow contrasted the situation of the Lavochkin design bureau with the more generously-funded human spaceflight program run by the Energiya and Progress design bureaus, possibly rightly so when human lives are at stake, Harvey pointed out.

“By contrast, meetings with Lavochkin took place not in the bureau but in adjacent hotels, not, it seemed because of secrecy but because under-investment in the science program would be so obvious,” Harvey said. “Underfunding may be the real root of what went wrong.”