Russia's Lunar Return


Note: this article was originally published in the 5 June 2006 edition of Aviation Week and Space Technology and is reprinted here by permission.

Russia, which pioneered and then abandoned robotic exploration of the Moon after loss of the Space Race and collapse of the Soviet Union, is starting the development of its first lunar mission in 30 years.

The ambitious flight, entering initial design, will include a lunar orbiter that, under the current plan, will also simultaneously deploy 13 probes across diverse regions of the lunar surface. This will include two penetrators that will be fired toward the Apollo 11 and Apollo 12 landing sites to acquire subsurface data to build on the manned exploration and instrumentation left at those locations 37 years ago by U.S. astronauts.

The Russian flight is also to shower 10 other higher-speed penetrators on the Moon that will form a seismic network to help solve questions about the Moon's origin.

The mother ship for the penetrators is then to drop a soft lander into a south polar crater to search for signs of water ice that would complement data from the planned 2008 U.S. Lunar Crater Observation and Sensing impactor mission to the same region (AW&ST Apr. 17, p. 26). The new "Luna-Glob" mission is now a formal part of the Russian space plan with launch set for 2012, says Nikolay F. Moiseev, deputy director of the Russian space agency. With the new lunar flight, Russia finally joins the U.S., China, India, Japan and Europe in renewed exploration of the Moon. But the program is also subject to future budget and technical risks.

The Russian lunar mission is to follow the launch in 2009 of a Russian sample return flight to the Martian moon Phobos as part of a renewal of Russian robotic planetary exploration, Moiseev told Aviation Week & Space Technology. Both missions have science goals related to the formation of bodies in the Solar System. The Phobos flight would help confirm theories about it being a captured asteroid, while the Luna mission would sort out competing theories of the Moon's origin.

The ambitious lunar flight would also add data to the theory that water ice, possibly useful to future lunar astronauts, may exist in permanently shadowed area of south polar craters.

The lunar mission is now "most definitely part of our plan" Moiseev said. It is to be launched on a Soyuz booster, or a Molniya version of the Soyuz with an extra upper stage.

The U.S., China, India and Japan are all planning to launch new orbiters to the Moon starting in 2008, and Japan is also developing its own lunar penetrator mission that would be much less ambitious than Russia's. The U.S. impacter would be part of the 2008 U.S. orbiter, but would not return data directly from the surface, as is planned for all 13 of the Russian probes.

At the height of the Cold War, the Soviet Union achieved many firsts in robotic lunar exploration. Between 1958-76, the USSR attempted the launch of 60 robotic lunar missions. Roughly 30 involved launch or trajectory problems, less of a challenge today, while about 10 failed on or near the Moon. About 20, however, were a total or partial success.

Major Soviet achievements included the first lunar flyby in 1959; the first lunar far-side photos in 1960; the first semi-soft lander to return images from the surface in 1966; a series of successful lunar orbiters starting in 1966; three robotic sample returns in 1970, '72 an '76; and two Lunokhod rovers in 1970 and '73. The two Lunokhods, nearly the size of Volkswagen Beetles, roved 6 and 23 mi. across the lunar surface, respectively.

The Soviets then turned their attention to robotic Venus exploration, where they also had great success, and Mars exploration, which largely failed. No Soviet lunar mission was launched after 1976 and no planetary missions were flown after the Mars 96 launch failure. In the mean time, the U.S. has launched major missions to Mercury, Mars, Jupiter, Saturn and to asteroids and comets.

Since Apollo, the U.S. also sent two orbiters to the Moon, and the Europeans currently have their Smart-1 spacecraft in lunar orbit.

The Lavochkin design bureau developed virtually all the earlier Soviet lunar and planetary missions and the new lunar and Phobos missions are also being developed there, Moiseev said. Although challenging, the mission is less complex than the lunar rover and sample return flights. The Moscow-based Vernadsky Institute of Geochemistry and Analytical Chemistry is helping to lead science payload development for the lunar mission.

"The stagnation of the planetary research program in Russia is especially regrettable as we have unparalled experience in the exploration of the Moon by automatic instruments," says Erik M. Galimov of Vernadsky in a report on the mission.

In a recent lunar science conference, Galimov said the new Russian missions "could be helpful in collaboration with countries planning their first lunar explorations, such as Japan, China and India."

A combination lunar orbiter/lander configuration is being designed for the Luna mission. It will carry three different lunar surface systems, including 10 High-Speed Penetrators (HSPs), two slower Penetrator/Landers (PLs) and the totally different Polar Station (PS).

Each of the 10 HSPs will carry a simple seismometer. About four days after launch, when the mother ship is 29 hr. from the Moon, a circular cassette carrying the 10 HSPs will be detached to fly the rest of the distance on its own. As it reaches 435 mi. altitude, it will be spun up to 20 rpm. for stabilization and release of the first five HSPs.

After they are released, the HSPs, which are shaped like air-to-air missiles without the aerodynamic fins, will be flying in formation toward the surface.

They will then begin to spread out, followed closely by the cassette carrying the other five HSPs. When the cassette reaches 217 mi. altitude, the second set of five will be released.

At that point, there will be 12 separate Russian lunar vehicles in flight above the Moon—the mother ship, theempty cassette and 10 HSPs.

The first five HSPs will impact the surface 250 sec. after release in a circle 6-8 mi. across, while the other five will impact in a tight cluster, forming an array of about 3 mi. across within the impact footprint of the original five.

The non-instrumented cassette would then also impact the Moon.

The HSP will hit with a velocity of up to 1.5 mi. per second with a force of 10,000g and burrow several feet, leaving a communications antenna on the surface. Although it is a development challenge, the seismometers and batteries in the penetrators are being designed to survive the impact.

The target point is the 900-mi.-dia. Sea of Fertility on the Moon's southeast face where analysis indicates the surface properties should allow good depth penetration.

This will form a small aperture seismic array capable of detecting specific characteristics of Moonquakes, caused by the gravitational pull of the Earth every month. The concept was conceived by the Institute of Earth Physics in Moscow. Each of these HSP seismic stations should land within 1-2 mi. of each other to provide an integrated data network.

With the HSPs released, the mother ship will continue toward the Moon, then release two other much different and more precisely targeted penetrator/landers. These PLs will carry more advanced instrumentation to detect broadband seismic data from far deeper in the Moon. They will also be equipped with two solid propellant braking rockets to greatly slow their descent.

At 1.2 mi. above the surface, the PL braking engines will fire to slow velocity to zero. The braking motors will separate and the penetrators will begin to freefall again, but with a maximum of 200-650 fps. at impact. The slower impact will mean they hit with only 500g. They, too, will dive below the surface and leave an antenna atop the entry hole.

One PL will be targeted for the vicinity of the Apollo 11 landing site explored by Neil Armstrong and Buzz Aldrin in July 1969, while the other will hit 190 mi. away near the Apollo 12 site explored by Pete Conrad and Alan Bean in November 1969. The objective will be to compare seismic data from these new penetrators with seismic data received from the seismometers left by the Apollo 11 and 12 crews and the new seismic data from the HSP penetrators further east. The Apollo 11 seismometer functioned for only three weeks, but Apollo 12's operated for five years on nuclear power.

The comparison of the seismic data should indicate the mass of the lunar core, which will be a giveaway as to how the Moon was formed.

One theory of its origin is that a Marssized object struck the early molten Earth, knocking off material that later coalesced to form the Moon. If that is the case, the Moonquake data should indicate the lunar core is only about 0.4% of Moon's total mass.

But, if the new quake data show that the core is significantly more massive, about 5%, it would indicate the Earth and Moon were formed separately out of ancient material in the planetary nebula.

After releasing the two PLs and 10 HSPs, the mother ship will enter a polar orbit around the Moon. It also carries the Polar Station lander that will be deployed to land in a 35-mi.-wide crater near the south pole, where analysis indicates water ice could exist in a permanently shaded area. The PS will carry a retro rocket and inflatable landing bag so it can touchdown as slowly as 16 fps. to deliever a mass spectrometer and neutron spectrometer as well as an additional seismometer to the surface.

The spectrometers will attempt to detect the presence of any volatile that could indicate nearby water ice.

The orbiter portion of the spacecraft still aloft over the Moon would relay data from the 10 HSPs, two PLs and single Polar Station back to Earth.

Copyright 2006 Aviation Week and Space Technology. Reprinted with permission .

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