Quote from: jcm on 02/15/2013 07:28 pmQuote from: R7 on 02/15/2013 07:23 pmQuote from: ugordan on 02/15/2013 07:15 pmDare I say around 1 megaton event?Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.New estimates based on infrasound stations (and I don't know how theyderive the result) claim 15m dia, 7000 tonnes, and hundreds of kT7000 tonnes ... "Wow" seems not enough I have no idea how this estimate was obtained, but I'm sure it's beyond my expertize.Lets compare with records -- Sikhote-Alin meteorite (belongs to the top 10 largest meteorites):estimated mass = 70 to 100 tonnesRecovered mass = 23 tentry speed = 14 km/secmore than a hundred of craters and severe damage to forest in epicenter.It fell in unpopulated remote area, but the sound was heard 300 km awayBright flash was seen from Vladivostok, some 450 km away.today:In Miass and Zlatoust (90 and 110 km to the west from Chelyabinsk) nobody heard a sound, they just enjoy a silent show.in the epicenter - broken windows and one abundoned building damaged by shock wave.no large craters reported so far. The only reported fragments are about 0.5 cm...estimated entry speed 15-20 km/secand yet on the top, it is 7000 tonnes...If so - it was very gentle and well behaving meteorite
Quote from: R7 on 02/15/2013 07:23 pmQuote from: ugordan on 02/15/2013 07:15 pmDare I say around 1 megaton event?Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.New estimates based on infrasound stations (and I don't know how theyderive the result) claim 15m dia, 7000 tonnes, and hundreds of kT
Quote from: ugordan on 02/15/2013 07:15 pmDare I say around 1 megaton event?Unlikely. Estimates have been ~10 tonnes and 20km/s, that gives 'just' 2TJ, little shy of half kiloton worth of KE.
Dare I say around 1 megaton event?
Quote from: Robotbeat on 02/15/2013 06:37 pmQuote from: Eric Hedman on 02/15/2013 06:08 pmLet the hearings begin!http://thehill.com/blogs/blog-briefing-room/news/283427-house-committee-to-hold-hearing-on-asteroids-that-pose-a-potential-threat-to-earthIt does make NASA less of a target for cuts (from just a social/political perspective).This is a legitimate threat to humanity and our nation. As real as North Korea or Iran.Sometimes I really have to wonder about space advocates who talk about how the public doesn't care and either how that's unfair/stupid or how it's inevitable. And when space DOES enter the public's eye, they brush it off, poo-poo it, and usually don't take the opportunity to educate people.It doesn't surprise me all that much that threats from NEOs are not talked about that much by space advocates. There is little to no relationship between asteroid threats and the various issues people tent to be passionate about (human spaceflight, Mars, etc.).
Quote from: Eric Hedman on 02/15/2013 06:08 pmLet the hearings begin!http://thehill.com/blogs/blog-briefing-room/news/283427-house-committee-to-hold-hearing-on-asteroids-that-pose-a-potential-threat-to-earthIt does make NASA less of a target for cuts (from just a social/political perspective).This is a legitimate threat to humanity and our nation. As real as North Korea or Iran.Sometimes I really have to wonder about space advocates who talk about how the public doesn't care and either how that's unfair/stupid or how it's inevitable. And when space DOES enter the public's eye, they brush it off, poo-poo it, and usually don't take the opportunity to educate people.
Let the hearings begin!http://thehill.com/blogs/blog-briefing-room/news/283427-house-committee-to-hold-hearing-on-asteroids-that-pose-a-potential-threat-to-earth
I agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen and ended up making half an orbit, like an Apollo/Zond skip reentry
Live updates:http://www.guardian.co.uk/science/2013/feb/15/meteorite-explodes-over-russian-urals-live-updatesIncredibly surreal event. All of a sudden, all eyes are on space...
Listening to the presser, they used infrasound detectors that were meant to detect nuclear airburst explosions. I would guess they are left from technology that would have detected the U.S. attacking the U.S.S.R. Scary.
Quote from: mlindner on 02/15/2013 08:22 pmListening to the presser, they used infrasound detectors that were meant to detect nuclear airburst explosions. I would guess they are left from technology that would have detected the U.S. attacking the U.S.S.R. Scary.Actually the main purpose of the US infrasound network (which is what NASA is using for these estimates) is it is part of the network (includes other tech) the US uses to detect secret nuclear testing by other parties (such as post Cold War entities like Iran, N. Korea, Pakistan, India, Manchester United). During the Cold War, once the US or USSR was attacked, it would have been to late to analyze the data from the network. It is still viable today, and is very viable for characterizing large impact events.
Quote from: jcm on 02/15/2013 07:29 pmI agree with Jorge's latest that it seems unrelated - unless maybe it aerobraked in the southern hemisphere unseen and ended up making half an orbit, like an Apollo/Zond skip reentryAmazingly, major orbital plane changes as a result of passage through the atmosphere have happened before:1972 Great Daylight Fireball
Quote from: yg1968 on 02/15/2013 06:44 pmIt's a good thing in my opinion. Oh, I agree there, but talk is cheap.
It's a good thing in my opinion.
What is the government doing about it?The US Congress held hearings to investigate the impact hazard in 1993, 1998, and 2002, and both NASA and the US Air Force are supporting surveys to discover NEOs. In 1998 NASA formally initiated the Spaceguard Survey by adopting the objective of finding 90% of the NEAs larger than 1 km diameter within the next decade (that is, before the end of 2008). In 1998 NASA also created a NEO Program Office, and today $3-4 million per year is being spent on NASA-supported NEO searches and orbit calculations. Other governments have expressed concern about the NEO hazard, but none has yet funded any extensive surveys or related defense research. A private Spaceguard Foundation based in Europe promotes NEO surveys internationally, and further interest on an international basis is provided by the International Astronomical Union, the International Council of Scientific Unions, and the United Nations.
Quote from: notsorandom on 02/15/2013 07:16 pmQuote from: Robotbeat on 02/15/2013 06:37 pmQuote from: Eric Hedman on 02/15/2013 06:08 pmLet the hearings begin!http://thehill.com/blogs/blog-briefing-room/news/283427-house-committee-to-hold-hearing-on-asteroids-that-pose-a-potential-threat-to-earthIt does make NASA less of a target for cuts (from just a social/political perspective).This is a legitimate threat to humanity and our nation. As real as North Korea or Iran.Sometimes I really have to wonder about space advocates who talk about how the public doesn't care and either how that's unfair/stupid or how it's inevitable. And when space DOES enter the public's eye, they brush it off, poo-poo it, and usually don't take the opportunity to educate people.It doesn't surprise me all that much that threats from NEOs are not talked about that much by space advocates. There is little to no relationship between asteroid threats and the various issues people tent to be passionate about (human spaceflight, Mars, etc.).Well, there actually are some similarities between human spaceflight missions and NEO threats. Early deep space missions (the Gemini of a Mars architecture) currently target NEOs for visits. In addition to any intensive study of a NEO from a HSF mission (which may not win by itself in a cost/benefit analysis against an unmanned mission or ten), if we're going to deflect an asteroid, having the ability to deploy a very large spacecraft using solar-electric propulsion to station-keep near the asteroid (and the proximity ops of asteroid missions) is quite relevant indeed, even though the actual deflection spacecraft would surely be unmanned.But the propulsion technology and scale needed for a significant gravity-tractor craft would be on the same level. And, of course, it fits in well with lunar and Martian operations as well (for tug and transfer vehicle work).The problem, however, is apparently a lot of HSF advocates are kind of prejudiced against any kind of asteroid mission for whatever reason, even though it's arguably easier to justify from a fundamental perspective.
New estimates based on infrasound stations (and I don't know how theyderive the result) claim 15m dia, 7000 tonnes, and hundreds of kT
NASA scientists have conducted a preliminary analysis of the event. "Here is what we know so far," says Bill Cooke, head of NASA's Meteoroid Environment Office. "The asteroid was about 15 meters in diameter and weighed approximately 7000 metric tons. It struck Earth's atmosphere at 40,000 mph (18 km/s) and broke apart about 12 to 15 miles (20 to 25 km) above Earth's surface. The energy of the resulting explosion was in the vicinity of 300 kilotons of TNT."
Also, some seismic data.http://earthquake.usgs.gov/monitoring/operations/station.php?network=IU&station=MAKZ#heliplot
Quote from: jcm on 02/15/2013 07:28 pmNew estimates based on infrasound stations (and I don't know how theyderive the result) claim 15m dia, 7000 tonnes, and hundreds of kTSpaceWeather.com is quoting 300 kT, maybe from the NASA teleconference...anyone happen to record that audio?From: http://www.spaceweather.com/QuoteNASA scientists have conducted a preliminary analysis of the event. "Here is what we know so far," says Bill Cooke, head of NASA's Meteoroid Environment Office. "The asteroid was about 15 meters in diameter and weighed approximately 7000 metric tons. It struck Earth's atmosphere at 40,000 mph (18 km/s) and broke apart about 12 to 15 miles (20 to 25 km) above Earth's surface. The energy of the resulting explosion was in the vicinity of 300 kilotons of TNT."
There is some efforts that are being made. See this link (the survey of NEAs larger than 1 km is not yet completed from what I understand):
Quote from: yg1968 on 02/15/2013 08:57 pmThere is some efforts that are being made. See this link (the survey of NEAs larger than 1 km is not yet completed from what I understand): The requirement was for 90%. They are at 95%. They are for all intents and purposes complete. You can never get to 100%.There is a requirement for searching for 140 meter NEOs. That's nowhere near done (I think they're at no more than 5%). See the report I linked to earlier for more details.Frankly, NASA doesn't want to do this, and nobody really wants to do this. A few members of Congress slipped some language into bills many years ago requiring NASA to do it, but nobody provided any extra money for them to do it. That's why it's largely not getting done. Simply put, the people who run the country do not think that this is an important issue, or even a minor issue, and never have.