No, NASA Is Not Bombing the Moon
Written by Nancy Atkinson
Artist concept of the Centaur and LCROSS heading towards the Moon. Credit: NASA
There seems to be a little lunacy making the rounds that NASA is going to "bomb" the Moon on Friday morning, or "hurt the Moon," or "split the Moon in half," or change its orbit. This is all just nonsense and scare-mongering, and those worried about our Moon can rest assured our lunar companion will remain in the sky relatively unchanged after this experiment to search for water ice on the Moon's south pole. Let's take a look at the physics involved and what might happen to the Moon.
First of all, there are no explosives involved. The LCROSS mission is going sending a upper stage of a Centaur rocket and a smaller spacecraft to impact the Moon. The two objects will create a crater — The 5,000-pound (2,270-kilogram) Centaur is expected to slam into Cabeus Crater on the Moon's south pole at a sharp angle at a speed of 5,600 mph (9,000 kilometers per hour). The Centaur's collision is expected to create a crater roughly 60 or 70 feet wide (20 meters wide) and perhaps as much as 16 feet (5 meters) deep, ejecting approximately 385 tons of lunar dust and soil — and hopefully some ice.
The LCROSS spacecraft itself, weighing in at 1,500-pounds (700-kilograms), will follow the Centaur by about four minutes and fly through the regolith plume thrown up by the collision, just before it too slams into the lunar surface, kicking up its own smaller plume of debris, all the while using its sensors to look for telltale signs of water, beaming the information back to Earth.
So, yes, it will make a rather big crater on the Moon. But one close-up look at the lunar surface will reveal that the Moon is full of craters, and still regularly receives hits by meteorites and larger space rocks – not as much as in the past, as most of the craters on the Moon are from an earlier period in our history when there was more debris left over from the formation of the solar system. The Moon was not "hurt" in the past, and it will not get hurt by this impact. Additionally, other spacecraft have hit the lunar surface with no adverse effects on the Moon or its orbit.
But will this impact change the Moon's orbit? Dr. Jeff Goldstein from the National Center for Earth and Space Science Education writes about this on his blog, Blog on the Universe:
The Atlas V Centaur upper stage has a mass of 2,000 kg (the more massive of the two vehicles impacting the Moon). It will be moving at 5,600 mph (2.5 km/sec.) BAM! By comparison, the Moon is orbiting the Earth at the measely speed of 2,300 mph (1.022 km/sec). On the other hand, the Moon is just a tad bit more massive than the specks on a collision course.
So let’s say we wanted to change the Moon’s speed by JUST 1 MPH (0.0004 km/sec)—which is less than 1/2,000th its orbital speed—and we were going to do it by hurling Atlas V Centaur upper stages at the Moon. How many would we have to hurl its way? HEY, let’s give every person on planet Earth an opportunity to hurl one. Would that do it? Uh … nope. Every person on Earth (all nearly 7 billion of us) would each need to hurl 1 MILLION Atlas V Centaur upper stages at the Moon. I’d rather just hurl one and not worry about it. Rest easy, sleep well, and let’s see if we can find water on the Moon at the South Pole.
Another question people have been asking: Will the impact destroy the water we are looking for?
NASA answers that question on the LCROSS FAQ site:
The LCROSS impact will have the same effect on the water (if it is indeed there) as any other object that might naturally impact it. Most (>90%) of any water that is excavated by LCROSS will most likely return to nearby “cold traps”. The LCROSS impact is actually a slow impact and, thus, most of the material is not thrown very high upward, rather outward, adjacent to the impact site. Of the water that does get thrown upward, much of it will actually return to the Moon and eventually find its way back to the dark, cold craters. This is actually one possible way that the water was supplied in the first place: it was deposited following the impacts of comets and asteroids.
There is about 12,500 square km of permanently shadowed terrain on the Moon. If the top 1 meter of this area were to hold 1% (by mass) water, that would be equivalent to about 4.1 x 1011 liters of water! This is approximately 2% the volume of the Great Salt Lake in Utah. The LCROSS impact will excavate a crater approximately 20 meters in diameter, or about one-trillionth the total permanently shadowed area. It is safe to say the LCROSS impact will not have a lasting effect on lunar water, if it does indeed exist.
See our previous article on how to watch the LCROSS event.
Filed under: Moon
Tags: LCROSS, MoonRelated stories on Universe Today
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October 8th, 2009 at 7:13 am
Nancy, you didn't start these wild stories off by any chance?
October 8th, 2009 at 7:20 am
The title of this article made me laugh as the sp*c*e.com feed above it on my iGoogle page has the title "NASA set to dive bomb the moon"
October 8th, 2009 at 7:32 am
You mean there are people where "LCROSS bombing the Moon" is not tongue-in-cheek?
October 8th, 2009 at 9:56 am
Spoodle58 –
Shhhh!
October 8th, 2009 at 10:02 am
This is why people need to take physics at least at the high school level. There is a momentum transfer: The momentum of the craft is transferred to the moon. Yet the ratio of the spacecraft to lunar mass m/M << 1 and so the change in velocity from mv = (M + m)delta V gives
delta V = mv/(M + m)
which is negligible.
LC
October 8th, 2009 at 12:39 pm
James McCanney had an interesting post today: Here's a portion:
Quote "…
The moon should have large quantities of surface OIL just like earth as it comes from the same source … OIL COMES FROM the tails of passing large comets that have ravaged earth and the solar system AS EARTH AND OUR MOON PASS THROUGH THE TAILS OF THE ANCIENT GREAT COMETS (not the puffy little ones like Halley's comet) … My theoretical work shows that hydrocarbons form as does water and thousands of other chemicals in the active ELECTRICAL TAILS of comets … when planets like earth AND OUR MOON pass through the tails of the LARGE comets THEY RECEIVE A BATH OF WATER AND HYDROCARBONS AND MANY OTHER ORGANIC AND INORGANIC CHEMICALS … the great comets talked of in ancient history ARE THE TRUE SOURCE OF OIL … EARTH AND THE MOON were blanketed with HYDROCARBONS … OIL …" (END QUOTE)
-from http://www.jmccsci.com/
October 8th, 2009 at 1:48 pm
workshop: Your post gave me a headache for more than one reason
October 8th, 2009 at 2:15 pm
James McCanney is a crackpot. Everybody knows our oil comes from the feces the dwarves and elves left everywhere during the hyborian age.
Sheesh!
October 8th, 2009 at 8:37 pm
"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. "
-Arthur Schopenhauer
October 9th, 2009 at 12:28 am
Not another crackpot fool.
So, do we go through the effort of debunking the many errors in his totally unsubstantiated claim? (actually, its no effort, it takes but a single word: Spectroscopy)
Or do we just assume that since he too is a useless quote miner, and will use denialism instead of proof in all his responses, that he is likely the same old crackpot that's been posting here for months under other names?
I can quote mine too!
"Crackpots are useless fools who never provide real proof – only unsubstantiated babble, feign ignorance of the scientific method, never directly and honestly answer questions with any real substance, never accept reality, and who will sadly plague the educated for as long as they continue to be permitted to use the internet"
- Surak
October 9th, 2009 at 12:58 am
Huh. It's not like it's the first time we 'bomb' the moon (or smaller bodies), and with bigger stuff too. Emily Lakdawalla reminds us of the 7 times heavier Atlas stage impact among others.
Surak, above all crackpots provide LARGE FONT.
And don't you love the EU nuttiness in "active ELECTRICAL TAILS of comets".
[Never mind that comets visibly have two tails (one charged ion tail and one near neutral dust tail). But when did a little fact keep in a cracked pot?]
I'll have another one word debunker: isotope ratios. [So it's two words - but who's counting?] No way anyone can suggest getting around biological processing resulting in the carbon ratios of oil.
Um, except a crackpot of course.
October 9th, 2009 at 1:10 am
Three robbers searching for treasure entered a cave with a sleeping female dragon. In the darkness, one felt the Dragon's teeth and thought it was a lion. Another felt the dragon's breasts and thought it was sleeping woman and another felt its tail and thought it was a giant snake. Each of them only had a piece of the truth, they were all right and all wrong. There is an article on this website that says "Analyses of the sunlight reflected off the asteroid also show that organic compounds are widespread on the surface, he added, including polycyclic aromatic hydrocarbons, CH2 and CH3.
October 9th, 2009 at 1:14 am
mind you i hate those bl**dy CAPITALs as well, it's like YOU ARE AN IDIOT SO WE WILL MAKE IT REALLY CLEAR AND EASY
October 9th, 2009 at 1:29 am
SteveZodiac (and workshop, and whatever other names you've chosen to write under)
You employ more common crackpot ploys … cherry picking of facts while ignoring massive piles of facts that do not support your claim, and using false analogies.
We know far far more about comets and asteroids than your blind dragon gropers know about their dragon. 'We' apparently does not include you since you chose not to be informed on the subject.
Funny how you didn't bother to mention how the organic compounds may be wide spread but are found in very small concentrations, basically no more than showing that they exist … so small as to be meaningless in the terms of the failed and utterly unsubstantiated claim.
What are you, a young earth creationist desparate to cover the ancient biological truth about the earth's hydrocarbon reserves to hide the earth's real age?
October 9th, 2009 at 8:07 am
We 'went' to the moon and took photos there! And that was years ago. And now, in 2009, we cant send anybody there to just scoop some soil away, dig one meter with a shovel and look for 'ice!!!'
There is something fishy about that. And while NASA is at at, why dont they take a photo of that flag they put there and show us?
October 10th, 2009 at 9:30 pm
@althene: The only thing that's "fishy" are the remnants of your brain if you can seriously offer up such inane dribble. Please, the fake flag argument… at least offer an original conspiracy theory.
October 11th, 2009 at 9:53 am
I really enjoy McCanney's comments from his website: (Quote)"October 09, 2009 posting #2 … NASA's moon crash occurred this morning BUT all i saw so far were [animations!] is nasa up to its old tricks again ??? and the news report i saw was given by a Russian scientist who could hardly speak english who talked in vague general terms … what is with that NASA ??? don't you have any american scientists left ???"(End Quote)
I recommend checking out his radio programs if you get the chance. They are free and they are archived here:
http://www.jmccsci.com/WeeklyRadioShowArchivesSubPage.HTM
October 13th, 2009 at 12:16 am
@ workshop,
I recommend that you click here.