LRO Locates Lunokhod 1 Rover and its Laser Retroflector

The first successful robotic lunar rover, Lunokhod 1, landed on 17 November 1970. For the next ten months the rover was driven by operators in the Soviet Union, with the total distance traveled exceeding 10 km. A French-built laser reflector was aboard rover, but after Lunakhod 1 fell silent on September 14, 1971, the location of the rover and retroreflector was unknown.

Laser retroreflectors are used by ground-based telescopes to pulse of laser light to the Moon and back. The time for the return tells the position of the retroreflector to less than a centimeter. This allows scientist to measure the shape or the moon as it bulges due to tides, the wobble of the Moon as it rotates on its axis, and the motion of the of Moon on its orbit to within an accuracy of one millimeter, or about the thickness of a paperclip. Three reflectors are required to lock down the orientation of the moon – the retroreflectors left by the Apollo 11, 14, and 15 missions are still routinely used for these measurements. Additional retroreflectors would allow determination of different lunar parameters and enable grater precision. Occasionally the Soviet Lunokhod 2 reflector has been used for this information, though it is severely degraded relative to the Apollo reflectors.

Ground-based observers had occasionally looked for the Lunokhod 1 reflector over the last two years, but faced tall odds against finding it until recently. The breakthrough came last month when the high-resolution camera on NASA’s Lunar Reconnaissance Orbiter, or LRO, obtained images of the landing site. The camera team, led by Mark Robinson at Arizona State University, identified the rover as a sunlit speck on the image (see below) —miles from where teams had been searching. On April 22, Tom Murphy at UCSD and his team used the 3.5 meter telescope at the Apache Point Observatory in New Mexico to find the long lost Lunokhod 1 reflector and pinpoint its location to 10 meters on the surface and 2 cm distance from the earth. Finding the Lunokhod 1 allows for much better geodynamics and studies of the lunar interior.

The Moon is a planet too

The Moon would totally be its own planet if it weren't orbiting the Earth. Also, it deserves its own capital letter. However, style-conforming blog post follows, from the LRO and LCROSS blog site. Enjoy!

Lunar scientist Barbara Cohen explains how our moon functions very much like a planet.

You've all probably heard about the International Astronomical Union (IAU) decision to define a planet -- probably because it clarified that there is a big belt of icy objects out beyond the orbit of Neptune, and we now know that Pluto is one of thousands of them. The IAU definition also excludes moons from being planets. But did you know our moon functions like a planet? It has a lot to teach us about how planets form and evolve.


Solar system rendering of the eight planets. (Image credit: Koolang Astronomical Observatory and Science Display Center)

Like the Earth, our moon has a crust, a mantle and a core. These interior layers we think are present on most planets, even if the crust is made of rock or ice. Mars probably has a crust, mantle, and core, and so do Venus and Mercury. The rocks we brought back from the moon from the Apollo missions helped us learn that this process of forming internal layers, or differentiation, is a common process on all planets. So when the moon formed, it formed like a planet.

Another hallmark of planets is that they have active geology. The big, dark splotches you see on the moon’s surface are lava flows. Yes, there were active volcanoes on the moon. There aren’t any volcanic cones, because the lava was very fluid and flowed out through cracks and into low-lying areas. The Apollo samples contain small beads of volcanic glass that tell us there were giant fire-fountains on the moon too. Though volcanic activity on the moon ended about 3 billion years ago, the Apollo missions picked up thousands of earthquakes on the moon, or moonquakes. Moonquakes tell us that the moon is not geologically dead. It's still acting like a planet today.


Hawaii Volcanoes National Park. (Image credit: Photo Credit: National Park Service)

My favorite part about planets is their impact craters, formed when asteroids or comets whizz into our part of space and collide. When you look at the moon, you can see that it preserves many impact craters on it for researchers like me to study. Did you know that all the craters you see on the moon (and there are hundreds of thousands of them!) had counterparts on the Earth at one point? We don't see many impact craters on Earth today because the Earth's crust continually renews itself and erases old rocks and formations. No one rock on Earth is older than 4 billion years. The Earth definitely got beat up by impacts from comets and asteroids in its past -- and that record is preserved for us to study on the moon.



For me, the best thing about the moon is that it may not be defined as a planet, but it definitely acts like one. Studying the moon allows us to learn about how all planets work. And because the moon is ancient, it's like a time capsule back into the early days of our solar system. But, I also love that the moon looks so beautiful reflecting sunlight to us on dark nights and I can't wait to get more information from our two lunar missions. Go LRO and LCROSS!

Lunar Reconnaissance Orbiter

This week, I am up at the Goddard Space Flight Center in Maryland for a project science meeting for the Lunar Reconnaissance Orbiter (LRO). LRO is our first step toward fulfilling the Vision, that is, gaining a foothold on the Moon and using it as a stepping stone toward explanding outward.

LRO is carrying seven instruments on board to look for water, understand the radiation environment, and acquire high-resolution information on topography, temperature, roughness, slopes, and imagery to characterize potential landing sites. At this point, the instruments are all built and undergoing individual acoustic, vibrational, and thermal vacuum testing. After they have been individually tested, they will be delivered to the spacecraft integrations center in the next two months. Then they will be integrated onto the spacecraft body and the whole thing will tested together.

LRO is scheduled for launch in 2008 on an Atlas V 401 rocket. No time to delay ops concepts or calibration for the cruise phase, as LRO takes a direct flight to the Moon in four days. The spaceraft spends a year in a circular polar orbit approximately 50 km above the Moon's surface, closer than any other lunar mission. During this time, it will be making global maps and acquiring observations for ESMD that they need to start planning for landing sites. After a year, control of the spacecraft will be turned over to science and while the spacecraft is still functional it will be used for science observations, possibly including a change of orbit to a more fuel-efficient elliptical orbit.

The LPRP at MSFC (where I work) is the program management office for LRO, Goddard manages the spacecraft, like integration and operations, and the seven instruments onboard all have individual principal investigators (PIs) and science teams. This makes LRO a much different flavor of space mission than, say, the Mars Exploration Rovers where we have a single PI and one coherent team. So, the project science meeting has been great for me to meet the team members (though I already know many of them of course), meet the management, and get instrument updates. The team spent a lot of time here discussing operations scenarios for when we actually get up there. There are some interesting ways of coordinating observations among instruments to make a richer science story than just simply leaving instruments switched on on a nadir-pointing orbit. But they take some time and agreement. We also spent some time thinking about how to co-register all the data together and tie it to the new reference frame that LOLA, the laser altimeter on LRO, will provide.

It definitely got me psyched for this mission, which we hope will be the first of many robotic missions to the Moon! But wait, why do we need LRO when there are three other international lunar orbiters, anyway? Next post, I'll tell you.