KAGUYA plunges into the Moon
Published on Jun 10, 2009 at 10:05 am.
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Filed under moon, space exploration.
The KAGUYA (formerly SELENE) spacecraft is at the end of its mission. As with several other recent missions to the Moon, KAGUYA’s final action will be a deliberate plunge into the lunar surface. The orbit has already been altered, and at this late time, there is not much that could stop it from slamming into the Moon. JAXA, the Japanese space agency, has released a map showing the anticipated impact site (reproduced here).
The impact will be near the far southwestern limb of the Moon (as seen from Earth). The impact time will be 18:25 UT (that is 1:25 pm Central Daylight Time here in the US). When the probe hits the Moon, it may create a flash or small plume. JAXA and astronomers are interested in any observations of anything that anybody sees. At the time of impact, though, the Moon will not be visible from here. In fact, it will be on the opposite side of the world. Observers in Asia, Europe, Africa, and Australia will have the best view. In fact, I’d imagine that India and Australia would be in prime position, with the Moon high in the sky at the time. I don’t expect any flash or plume to be visible in binocular, and certainly not with the naked eye. Most likely, you’d need at least what would be a medium or large amateur astronomer sized telescope to see anything.
This is not the first time that spacecraft have slammed into the lunar surface. In fact, the first spacecraft to reach the lunar surface, the Soviet Luna 2 spacecraft, did just that on September 13, 1959. Since it is easier to just run into the Moon than to try to land on it, the first American spacecraft to the lunar surface (the Ranger program) also was designed to crash into the lunar surface, a maneuver refered to as a hard landing. Ranger 4 was the first to actually accomplish this, on April 26, 1962. Ranger 4 ran into the far side of the Moon, making it impossible for data to be returned to Earth. Actually, the spacecraft had failed and was sending little data back, so it really would not have mattered. The first Ranger to actually run into the Moon with the cameras running and sending information back to Earth was Ranger 7, which impacted on July 31, 1964.
The first attempts to reach the lunar surface were hard landers because that is easier than trying to land intact. Eventually soft landings occurred, too, of course. But, you can learn a lot from studying a body from orbit. So, many missions to the Moon were placed into orbit around it. In the 1960s, both American and Soviet unmanned spacecraft were placed into lunar orbit. At the end of their missions, the American spacecraft were generally given a command to plunge into the Moon. Many of the Soviet spacecraft continued to orbit until the spacecraft was no longer functioning. This was a point of contention between the two respective nations and their space programs. After all, NASA was in the midst of a very public race to land men on the Moon by the end of the decade. The Soviets were also trying to send men to the Moon, but their manned lunar program was not progressing as well as the American one, and ultimately failed. There was some concern expressed that all of the orbital debris around the Moon from leftover spacecraft could pose a hazard to the Apollo missions. The concern was further compounded by the fact that there was no way to reliably track spacecraft in lunar orbit once they had ceased to transmit. It was hard enough to track Earth orbiting space debris. But, the Moon was simply too far away to be able to track of all of the debris orbiting it. The Soviets, of course, pointed out that the likelihood of one of the handful of old spacecraft orbiting the Moon hitting anything else was extremely small. Still, this was a point of contention between the two nations (one of many in those days).
Soon after the end of the Apollo missions, the Soviets quit sending Luna spacecraft to the Moon, too. For nearly two decades the Moon received very little attention. Things changed, though, with the Navy’s Clementine spacecraft. A testbed for technology, the Clementine mission used instruments that revealed a great deal of detail on the Moon, and renewed scientists interests in that nearby world. A startling finding, though, was that radar reflected from some of the craters in the southern polar region of the Moon that seemed to indicate the possibility of ice on the Moon. The discovery is significant, because the Moon rocks brought back by the Apollo astronauts show that the Moon is amazingly deficient in water. The ice in the polar regions would presumably be the result of trapped water vapor resulting from the impact of comets on the lunar surface. Ice on the Moon may have been somewhat unexpected, but it wasn’t totally surprising. A few years earlier, the Arecibo radio telescope had found similar deposits in the polar craters of Mercury. Still, the finding was something significant.
So, when NASA sent another spacecraft to the Moon in 1998, the Lunar Prospector, one of its goals was to look for evidence of ice in the polar craters. Lunar Prospector failed to find the ice that the Clementine data suggested. At the end of the mission, the Lunar Prospector was deliberately crashed into the lunar surface into one of the craters that was suspected of having ice in it. The hope was that a cloud of material spit out by the impact would show the spectral signature of water. However, water was not found. Later missions have continued to look for ice in the southern lunar craters, without finding the large amount that had been hoped for. Further radar studies of the Moon suggest that the radar data from the Clementine mission may have been misinterpreted, and that large deposits of ice may not exist on the Moon after all. But, the hunt for possible ice still goes on.
More recently, the European SMART-1 spacecraft also plunged into the Moon on September 3, 2006. Rather than slamming into a polar region, though, SMART-1 crashed into the face of the Moon in a spot visible from Earth. Large telescopes on Earth were able to observe the flash of the impact, and the impact site itself has been subsequently studied. The impact site is an artificially created crater, exposing fresh material onto the surface of the Moon. Much of the surface material has been slightly altered by eons of exposure to the Sun and cosmic rays, so this gives an opportunity to see lunar material that is fresh.
Like these recent missions, the impact of KAGUYA is seen as not only getting rid of space debris, but an opportunity to study the Moon by observing what gets thrown out by the impact itself. This is a very clever way of disposing of an old space probe, using the kinetic energy of the body of the fast moving spacecraft to excavate material.
-Astroprof
Image courtesy JAXA
June and July Star Parties
Published on Jun 9, 2009 at 8:28 pm.
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Filed under observing.
For many people, summer is a time to get out and do things. Many amateur astronomers like to observe in the winter because the skies are often clearer, darker, and the nights are longer (permitting more observing and observing starting earlier). Serious amateur astronomers know how to dress for cold weather. However, for most other people, the summer months are when they think about doing such things. So, this summer, I am helping the Texas Department of Parks and Wildlife host two star parties at Dinosaur Valley State Park. For those of you who are not familiar with the term, a “star party” is a night of observing the sky. I typically start the event with a public lecture once it gets dark enough to see the projector. Often I have friends who are amateur astronomers come with their telescopes. I bring either a couple of my telescopes or some of the college’s telescopes. By the time I finish talking, it is dark enough to see things in the sky, so we observe for a while. The event is free (other than the standard park admission) and open to everyone.
The dates for the star parties this summer are June 27, 2009, and July 18, 2009. Sunset occurs about 8:42pm on June 27 and 8:37pm on July 18. So, I’ll be starting talking soon thereafter. It won’t be dark enough to do much viewing until after 9pm both nights. Usually my pre-observing talks say a bit about what we will be observing, and a bit about some other topic. The July 18 star party will be right before the 40th anniversary of the Apollo 11 landing on the Moon, so naturally that will be focus of that talk. So, if you are in this part of Texas on those nights, think about dropping by.
-Astroprof
CoS 106
Published on Jun 7, 2009 at 11:26 am.
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Filed under blogging.
The 106th edition of the Carnival of Space is now up at the Next Big Future blog. This week’s carnival has 28 blog entries gathered from the spacey bloggers around the blogosphere. So, go check out the links. The topics include astrophotography, meteors, new moon maps, and interstellar spacecraft engines.
-Astroprof
The Moon and Antares
Published on Jun 6, 2009 at 1:41 pm.
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Filed under observing, skywatching.
As the Moon goes around the Earth, it naturally passes in front of various stars now and then. The heavens are full of stars, so this is a pretty normal occurrence. When my students are doing their moon observations through the telescope, I often look to see if a star is near the limb (the astronomical term for the visible edge) of the Moon. I have the students watch to see if the Moon is getting closer or farther from the star over the course of the lab. Once in a while, we get lucky. As we are watching the Moon passes in front of the star. This is called an occultation. Most of the stars that are occulted, as I said, are pretty dim. Once in a while, though, a really bright star is occulted. That is happening tonight. The Moon will pass in front of the star Antares (the brightest star in the constellation Scorpius). Antares is a rather distinctive star. It is one of the stars that has a noticeable color. It appears orange or reddish. In fact the name Antares means Rival of Mars. The star Antares is about the color and brightness that Mars typically appears in the sky.
Antares is a quite bright star, easily visible with the naked eye. Normally, that makes an occultation very easy. However, the Moon will be very nearly full, and that will complicate the matter. I’d suggest using a pair of binoculars if you want to observe the event. If you want to observe the event, you ought to look up when it will happen for your particular location. That will vary a little from place to place. The International Occutation Timing Association has a web page dedicated to this particular occultation, and it has the needed information. One word of caution, though, about using that web site. The times given are Universal Time. That is NOT the time that your clock reads. You will need to find out how far your local time varies from Universal Time, which is the local mean time at the Prime Meridian (often called Zulu Time or Greenwich Mean Time). For here in Fort Worth, the dissapearance will occur at 01:53 UT. That is 8:53PM Central Daylight Time (what the clock reads). This will be a very difficult event to observe. You will need to be in exactly the right spot, because the Moon will be only about 7 degrees above the horizon. That is quite low, so you must find a spot where you can see the eastern horizon and catch the Moon before the event happens. It will have just risen about half an hour before it passes in front of Antares. The star, itself, will rise immediately after the Moon. In binoculars, you would see something like the following image right before the occultation.
The entire event will occur during twilight, so you might have trouble seeing Antares without binoculars. For observers farther east, this will be much easier to see. Florida and the entire east cost of the US should have a wonderful view. Unfortunately, observers in Europe are not properly placed to observe the occultation, though they will see the Moon passing very close to Antares. Observers in the western United States miss out because the Moon will not have risen at that time. Part of Canada (south of Hudson Bay) see the occultation. The rest of Canada misses the event, though. They will see the Moon pass right by Antares, in an event known as a conjunction. Central America gets to see the entire event, though, as does the northern part of South America. Most of South America sees a conjunction on the opposite side of the Moon from what Canada sees. Observers in the Carribean probably get the best view.
But, the Moon keeps moving, and it eventually moves out from in front of Antares. This will occur after the end of twilight here, as seen in the following image.
Here in the Fort Worth area, the reappearance will happen about 03:08 UT (that is about 10:08 CDT). At this time, the Moon will be 19 degrees above the horizon, much easier to observe. Still, I think that binoculars will help the observing because Antares will be appearing on the more lit side of the Moon (remember, it is just before full).
I always like observing occultation events. It is dynamic, and you actually get a chance to observe that things are moving in the sky. If you get a chance, go out and look for the event (especially if you are in Central America, northern South America, or eastern North America).
-Astroprof
Images created using Stellarium software
Full Crew
Published on May 27, 2009 at 11:38 am.
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Filed under space station.
The Soyuz TMA-15 lifted off some hours ago to carry three crew members to the International Space Station. At first glance, this might not seem so unusual. After all, Soyuz spacecraft have been visiting the ISS for some time. When the Space Shuttle was not flying, the Soyuz was the only way to and from the station. After the Space Shuttle ceases operations, then the Soyuz craft will once again be the way to and from the space station. What’s different, though, about this mission is that the crew heading to the Space Station are not going to simply replace the crew already there. Instead, the new crew are staying, and so are the crew members already at the station (at least for a while). This means that the ISS is finally up to near its planned full staffing. This is the first time that so many people have been at the space station at one time other than while a shuttle was docked (and that was only temporary).
So, why is this important? Part of the goal of the ISS is to learn to work in space. The ISS is supposed to be a research facility. The crew are supposed to be doing science and engineering experiments. They are learning how materials behave in a microgravity environment. Scientific experiments require controlling variables. If gravity influences an experiment, then you may be able to learn something by changing that variable. But, you can’t change gravity on Earth. You can do a research flight on an aircraft, as I did in January, where gravity is effectively reduced for a few seconds at a time, but sometimes that is not enough. You need to have an extended period of time with low gravity. That is the beauty of a space station. You can have all the time you want with low gravity. There have been many discoveries made in microgravity. A number of important pharmaceutical products have been developed. There have been discoveries in material science, biology, etc. I don’t have time to go into all of the benefits coming from space-based science, but you can check out the NASA web site for all sorts of spin-offs.
While some experiments are autonomous (they are delivered to the space station, ignored by the crew, and retrieved by a later mission), others require continual crew involvement. The crew can only do the science part of their mission, though, when they have time. However, space is a very harsh and unforgiving environment. Space travel is filled with perils. The lives of the crew require that the space station be operating as it is supposed to. But, the space station is a very complex piece of equipment. The space station operates as an orbiting spacecraft of limited maneuverability. It requires a crew to keep it running. I remember reading a number of years ago that it took roughly most of the time of two crew members just to keep the station operational: fixing the things that need fixing, adjusting the things that need adjusting, and other routine station operations. That means that with a crew of three, there is only the equivalent of one person doing science. That was the reasoning behind trying to get the station fully staffed as soon as possible. I do not have any reason to believe that those numbers have changed significantly. The station is more nearly completed, so some of the tasks would ease up, but the station is also larger than it was then, so there will be other tasks. Soon, the station will be growing old enough that more things will need to be repaired as they break.
After the Columbia loss, the crew was cut back to two because the Russian Progress modules could not supply enough supplied for the full three person crew then on board. Consequently, far less science was done until the Space Shuttle fleet was up and running again. Well before the space station was constructed, there were plans for a crew transfer vehicle and an escape vehicle that were to be associated with the ISS. These would permit a much larger crew onboard. For safety reasons, no crew larger than that which can be safely evacuated are permitted on the space station. Since the crew escape vehicles were never constructed, Soyuz craft are used as life boats. They can hold only three crew. For a long time, only one Soyuz at a time was available, so only three crew members could be at the space station at a time. The other problem, though, was a logistics problem. Crew members eat, drink, and require oxygen. The Progress modules could only ship supplies for two crew members. The Space Shuttle, though, with its larger cargo bay, can carry far more supplies to the space station (often in the form of a temporary module attached to the space station filled with supplies). So, space shuttle flights supplemented the Progress modules. But, even so, supplies were limited. Space Shuttle flights never became as frequent as they had been billed to become back in the late 1970s and early 1980s. And, of course, the Space Shuttle fleet is about to be retired. So, what is to come of the ISS?
Fortunately, the European Automated Transfer Vehicle (ATV) is now operational, and it is far larger than the Progress modules. Its larger cargo capacity means that it can supply a space station with a much larger crew. The ATV has proven to be reliable, so now is the time to send a larger crew to the space station. With the larger crew, the real work of the station can begin. This will begin a time in history marking the largest number of people working in space on a continual basis since the dawn of the space age. It is exciting.
-Astroprof
Images courtesy NASA, NASA TV
Memorial Day
Published on May 25, 2009 at 1:54 pm.
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Filed under Uncategorized.
Almost every nation has a day to honor those who have died in defense of their county. The day goes by different names, and it is celebrated at different times of the year. In the United States, it is Memorial Day. Traditionally, Memorial Day is May 30. However, in 1968, the day was changed to the last Monday in May. That makes for a three day weekend. Unfortunately, this emphasises the “play” aspect of the day rather than the original meaning, to remember those who have died to protect our freedom. Most people use the day to have picnics, barbeques, sales, and for sporting events rather than to honor the war dead.
So, take a moment today to remember what the day is supposed to be for.
-Astroprof
Image courtesy NASA
A new NASA administrator, finally?
Published on May 23, 2009 at 11:32 am.
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Filed under NASA, politics.
Michael Griffin, NASA’s previous top administrator, stepped down January 20, 2009. NASA has been without a top administrator ever since. Now, that does not mean that NASA has been aimless or without leadership. Christopher Scolese has been serving as acting administrator since Griffin stepped down. But, an acting administrator is not the same thing as an administrator. It sends the wrong message to NASA if the president doesn’t appoint someone. It also sends a subtle message that perhaps he doesn’t think that space exploration is all that important. So, it is important for him to find someone to lead the agency quickly.
Selecting a NASA administrator, I am sure, is tough. While this is an important position, it is also a political position. The decision of who should run NASA is as much a political appointment with political ends and statements as it is an appointment of someone to oversee the nation’s space agency (and aeronautics, let’s not forget that part of NASA, too). There have been a lot of rumors and suggestions for nearly half a year. Back in January, it looked like someone was going to be named, but that didn’t work out. There have been others. So, I didn’t want to write anything more until it looked pretty certain. Now, the news reporters are reporting that President Obama is appointing Charles F. Bolden to be the new NASA administrator. This time, the reports look pretty good.
Bolden is an interesting choice, particularly after such a long time. He is a former astronaut, having flown four missions, which would suggest that he would be an excellent choice to lead the space agency. One of his missions was STS-31, the flight that deployed the Hubble Space Telescope. He is a retired Marine major general, so he should have good leadership capabilities. He has been doing military and aerospace consulting for the last few years.
The same report names Lori Garver, another space consultant, as being about to be appointed as deputy administrator. Garver served three years with NASA administering policy and plans, and she served as a spokesperson for the agency. She appears to be a strong proponent of private space enterprises, and would likely work to strengthen relationships between NASA and private space firms. She is also a past executive director of the National Space Society.
None of this is a done deal, of course. Things are often quite fluid in Washington. The Senate will have to confirm Bolden’s appointment, of course. But, this nomination looks like it will go through. In fact, both nominations seem to be reasonable choices.
-Astroprof
Image courtesy NASA
