Talk:Near-Earth object

message: The material in the subsection "Close approaches and forecasts" doesn't belong in the Impact event article; they didn't cause impacts. Here is the text copy-and-pasted if someone wants to incorporate it into this article:
For some reason it created its own section. It follows this one.
Bettymnz4 (talk) 03:01, 7 April 2010 (UTC)
thread_title:  Text copy-and-pasted from Impact event 

message: On May 19, 1996, a  asteroid, 1996 JA1, passed within  of Earth; it had been detected a few days before. 
On March 18, 2004 a 30 m asteroid, 2004 FH, passed within 40,000 km of Earth only a few days after it had been detected.  This asteroid probably would have detonated in the atmosphere and posed negligible hazard to the surface, had it been on impact course.
On March 31, 2004, a  meteoroid, 2004 FU162 made the second-closest approach on record (closest so far was The Great Daylight 1972 Fireball) with a separation of only 1.02 Earth radii from the surface ().  Because this object is certainly too small to pass through the atmosphere, it is classed as a meteoroid rather than an asteroid.
In 2004, a newly discovered  asteroid, 99942 Apophis (previously called 2004 MN4), achieved the highest impact probability of any potentially dangerous object.  The probability of collision on April 13, 2029 is estimated to be as high as 1 in 17 by Steve Chesley of NASA's Jet Propulsion Laboratory, though the previously published figure was the slightly lower odds of 1 in 37, calculated in December 2004. Later observations showed that the asteroid will miss the earth by  (within the orbits of communications satellites) in 2029, but its orbit will be altered unpredictably in a way which does not rule out a collision on April 13 or 14, 2036 or later in the century.  These possible future dates have a cumulative probability of 1 in 45,000 for an impact in the 21st century.
Asteroid 2004 VD17, of , previously was estimated to have a probability of 1 in 63,000 of striking earth on May 4, 2102 (as of July 2006), with risk 1 on the Torino scale, but further observations lowered the estimate.  As of the observation on December 17, 2006, JPL assigns 2004 VD17 a Torino value of 0 and an impact probability of 1 in 41.667 million in the next 100 years.
Asteroid (29075) 1950 DA has a potential to collide with Earth on March 16, 2880. The probability of impact is either 1 in 300 or zero, depending on which one of the two possible directions for the asteroid's spin pole is correct. This asteroid has a mean diameter of about . The energy released by the collision would cause major effects on the climate and biosphere and may be devastating to human civilization. 
Asteroid 2007 TU24, with an estimated diameter between , came very close to earth orbit by 1.4 ld (lunar distance) on January 29, 2008. The orbit of the asteroid is shown on NASA's website.2007 TU24 (Java applet), JPL Small-Body Database Browser, Jet Propulsion Laboratory
Relatively small objects that burn up in the atmosphere can be dangerous beyond their own capabilities. In 2002, U.S. Air Force Brig. Gen. Simon P. Worden told members of a U.S. House of Representatives Science subcommittee that the U.S. has instruments that determine if an atmospheric explosion is natural or man-made, but no other nation with nuclear weapons has that
detection technology. He said there is concern that some of those countries could mistake a natural explosion for an attack, and launch nuclear retaliation. In the summer of 2001 U.S. satellites had detected over the Mediterranean an atmospheric flash of energy similar to a nuclear weapon, but determined that it was caused by an asteroid.
As of March 2008, the Near-Earth Asteroid with the highest probability of impact within the next 100 years is 2007 VK184, with a Torino scale of 1.Current Impact Risk (NEO JPL NASA)2007 VK184 Impact Risk Summary, NASA Near Earth Object Program.2007 VK184 Orbital Diagram  
Bettymnz4 (talk) 03:00, 7 April 2010 (UTC)
thread_title: Close approaches and forecasts

message: With all due respect to the editors who worked on this admittedly important section, I found the version I saw yesterday to be very problematic:
* One of the main sources was low-quality (an article with no sources on permanent.com, the personal webpage of a somewhat cranky enthusiast) and thus needed replacing.
* There is a sentence with stats showing that most NEOs are discovered near opposition. The stats are without context, the source that was given was wrong, and I tracked down that it is original research by a user for the creation of , and thus violates WP:OR.
* Many other sources were used inappropriately, to support claims they didn't make or with the claims they did make conflated with another.
* The description of the various biases was also too imprecise (probably still is in the new version).
Sadly, what appears to be the seminal work on observational biases, Bottke (2000), is behind a paywall, and I didn't find a good popular-science-level overview article either, so the section could probably still see significant improvement.
Rontombontom (talk) 10:27, 26 January 2024 (UTC)
thread_title:  Observational biases section re-write 

message: The five diagrams presently included in the article are all problematic for different reasons. I made a request for a new diagram at WP:GLI. Rontombontom (talk) 17:24, 27 January 2024 (UTC)
replies: text: Forgot to add: this was quickly solved, Nsae Comp found & inserted a public-domain NASA diagram instead. Rontombontom (talk) 16:55, 31 January 2024 (UTC)
thread_title:  Diagrams showing orbital classes 

message: While the article has a section on "Artificial near-Earth objects" they aren't mentioned in the lead. Putting a mention there might give undue weight to the topic; perhaps merely adding the word "natural" somewhere in the lead would improve the article? (sdsds - talk) 22:07, 31 January 2024 (UTC)
thread_title:  Artificial vs. natural near-Earth objects 

message: While obvious to the knowledgeable reader familiar with small solar system body topics, the article might be improved for general readers by explicitly mentioning that Earth's Moon is not considered a near-Earth object since it is a natural satellite. (sdsds - talk) 22:18, 31 January 2024 (UTC)
thread_title:  Explicitly excluding Earth's Moon 

message: Please review my recent edit in the Exploratory missions section. It attempts to get at the concept of delta-v being a measure of acceleration rather than velocity. Another way to do this might be to explicitly link Δv.
:I further re-worded it.
:I'm not sure what you mean with acceleration, and I may be missing something as I am no rocket scientist, but here is my understanding. Delta-v will be the time integral of acceleration over the time periods the rocket is fired. Low acceleration over a long time can achieve the same delta-v as high acceleration over a short time (see ion engines vs. chemical rockets). If you check the Tsiolkovsky rocket equation, using a given propellant with a specific effective exhaust velocity to deliver a given payload, delta-v is a function of only the initial total mass, whatever the acceleration. (Staging & atmospheric resistance will of course complicate things.) Rontombontom (talk) 19:58, 19 February 2024 (UTC)
replies: text: Yes that's correct, delta-v is measured in units of velocity, and is the integral of acceleration over time. The current phrase 'sum total of changes in orbital speed' expresses that well. Thanks! (— 𝐬𝐝𝐒𝐝𝐬 — - talk) 21:10, 19 February 2024 (UTC)
thread_title:  Exploration mission delta-v requirements