GRAIL: Another Lofty Quest (Part 10), Next Stop: The Moon! December 31, 2011Posted by Lofty Ambitions in Science, Space Exploration.
Tags: GRAIL: Another Lofty Quest, GRAILTweetup
In September, Doug spent five days on the Space Coast participating the NASA Tweetup for GRAIL, the Gravity Recovery And Interior Laboratory. We covered this launch extensively (HERE is the link for all GRAIL-tagged posts, or click on the GRAIL title in the tag cloud in the sidebar).
Suffice it to say, as with attending most rocket launches, schedules don’t really mean much. Launch windows are set, but if everything doesn’t line up in those seconds, there’s usually the next day. After two delays, the Delta-II rocket launched on Saturday, September 10. Doug was there to capture some amazing images (see the launch photos HERE).
Today, that mission enters a new phase. At 1:21 PST, the first of the GRAIL twins, GRAIL-A (the mission requires two mirror-twin satellites, A and B) begins a 40-minute lunar orbit insertion burn that will leave the 440 lb satellite in an elliptical orbit over the lunar surface. Think surfboard shaped, with your back foot as the Moon and the satellite tracing the shape of the board. The back of the board, or the lowest point in the orbit is known as perigee, and the front of the board, or highest point in the orbit is known as apogee. (We really have gone all SoCal.)
GRAIL-B will start its 39-minute lunar orbit insertion burn tomorrow at 2:05 PST. Over the next several weeks, each satellite will undergo twenty separate corrections to leave them in the circular orbit (34 miles high, or roughly the distance from Naperville to Chicago) necessary for the science phase, which begins in March. At that time, the spacecraft will map the Moon’s gravitational gradient. During the science phase, the separation between the two craft will vary from 62 to 140 miles.
Considering the investment, both in the number of decades and the dollars (and rubles, euros, yen, yuan, and rupees—Russia alone has sent twenty missions to the Moon), that we have made in understanding our planet’s lone natural satellite, we still have shocking gaps in our knowledge about our nearest neighbor in the heavens. Fundamental questions such as why the light and dark sides of the moon are so completely different (the dark isn’t just dark because sunlight doesn’t reach it, but is actually made of different materials than the light side) remain only partially answered at best. If all goes well for the GRAIL twins, in the very near future we will begin to address a host of questions regarding the Moon. GRAIL principal investigator Maria Zuber estimates that the science mission of GRAIL will increase our knowledge about the Moon’s light side by a hundred times and the dark side by a thousand times. (If you read our earlier post this week HERE, you know this means we will be increasing our knowledge about the light side by two orders of magnitude and the dark by three).
Doug’s trip to the GRAIL NASATweetup was just one of our four (yes, four!) separate trips to NASA’s Kennedy Space Center and the Space Coast in 2011. Reflecting on those trips reminds us what a remarkable year this was for us. It also points out the futility of attempting to predict the future. A year ago today, we certainly were kicking around the idea of heading back to the Space Coast to catch one of the final space shuttle launches, but we knew we’d miss the February launch of Discovery because of our work schedules so we weren’t sure what our opportunities might be. We knew we had to go back, and we remain grateful that Chapman University recognized what the subsequent trips might mean for us.
As we conclude 2011, we wish all our readers and followers a happy new year. Look up at the Moon tonight—you won’t be the only one peering at it—and imagine a great year opening before all of us.