Silencing the crazy “Do not bomb the Moon” outcry

October 8, 2009 10:37 by scibuff

Tomorrow, the spaceflight part of NASA’s LCROSS (Lunar CRater Observation and Sensing Satellite) mission will end as the two main components, the Shepherding Spacecraft (S-S/C) and the Centaur upper stage rocket, impact the Cabeus crater located about 100km from the Lunar south pole.

An artist's impression of the LCROSS spacecraft's Centaur stage crashing into the surface of the Moon. The LCROSS spaceraft will observe and record the impact and then it also will crash into the crater - Image Credit: NASA

An artist's impression of the LCROSS spacecraft's Centaur stage crashing into the surface of the Moon. The LCROSS spaceraft will observe and record the impact and then it also will crash into the crater - Image Credit: NASA

Immediately after the LRO/LCROSS launch on June 18, science illiterate members of the blog community started a campaign to stop NASA from “Bombing the Moon”; an act, which, according to them, was in a clear violation of the UN resolution 2222 written in the 1499th plenary meeting on December 19, 1966 – Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies. I will not support this insanity by providing links here (just google “NASA Moon bombing”).

The arguments on blogs range from the creation of (up to) 8km deep crater, to the bombing constituting a hostile act against known extraterrestrial civilizations and settlements on the Moon allegedly observed by the crew of Apollo 11 (seriously?). Several magazines and newspapers (the likes of Scientific American, the Examiner and the UK Telegraph – no surprise there) jumped on the bandwagon featuring articles with an unfortunate (but I suspect a rather deliberate) word choice – “Moon bombing”.

Asteroid impact the Moon

Bombing can be defined as detonation (on impact) of an explosive devise producing a chemical action which causes a sudden formation of a great volume of expanded gas. In other words, nothing close to the events which are about to occur near the Moon’s south pole.

Let me assure you: the Moon is hit by space junk on regular basis. It has withstood this bombardment for billions of years and it will prevail for many billions to come. The flash in the sequence below was caused by a meteoroid about 25 cm in diameter traveling at 38 km/s. As such, although much smaller than either the (S-S/C) and the Centaur, the energy released in the impact is comparable with tomorrows impacts because this piece of rock was traveling fifteen times faster than LCROSS.

A meteoroid hits the Moon, May 2, 2006; video-recorded by MSFC engineers Heather McNamara and Danielle Moser.

A meteoroid hits the Moon, May 2, 2006; video-recorded by MSFC engineers Heather McNamara and Danielle Moser.

The Centaur upper stage will impact the lunar surface at around 11:31:20 UTC at -84.675, 311.275 E (in selenographical coordinates). NASA estimates the impact velocity of 2.5 km/s which will excavate more than 350 tonnes of lunar material and create a crater 20m in diameter with a depth of about 4m; in other words, nowhere near the sensational 8km (given the crater size, not even the Hubble Space Telescope will be able to see it under ideal conditions).

Using theĀ nominal impact mass of 2,305kg and the velocity of 2.5km/s the kinetic energy of the spacecraft can be easily calculated as

E=\frac{1}{2}mv^{2}=0.5\times 2,503kg\times \left ( 2,500m\cdot s^{-1} \right )^{2} = 7,203,125,000\ J

E\simeq 7.2\times10^{9}\ J

Since a kiloton of TNT is equivalent to 4.184\times10^{12}\ J, the total energy released in the impact (under ideal conditions) is 0.001\ 72 kiloton of TNT; again, nowhere close to the 2 kiloton of TNT (which equals to 10% of the yield of the bomb that destroyed Hiroshima) claimed by some authors. Furthermore, both the S-S/C and Centaur performed a blow-down maneuver to vent any remaining fuel inside the Centaur to help prevent contamination of the impact site and the ejecta material, thus there will be no explosion.

The Shepherding Spacecraft will impact the lunar surface roughly four minutes after the Centaur upper stage, at around 11:35:39 UTC at -84.729, 310.64 E, ejecting about 150 tonnes or material leaving behind a crater 14m wide and 2m deep.

LCROSS Shepherding Spacecraft and Centaur upper stage impact sites - Source: NASA

LCROSS Shepherding Spacecraft and Centaur upper stage impact sites - Source: NASA

As for the last argument, if you truly believe in the conspiracy to cover up the presence of an extraterrestrial civilizations on the Moon, reported in witnessed statements by astronauts Buzz Aldrin and Neil Armstrong, and in witnessed statements to NSA (National Security Agency) photos and documents regarding an extraterrestrial base on the dark side of the Moon (let’s forget for a second that there is NO such thing as the “dark” side of the Moon), I applaud you for reading this far and let’s just leave it at that…

Moon Defence