2011 ES4

Apollo near-Earth asteroid September 2020 yes #FFC2E0 2011 ES 4 MLS Mount Lemmon Obs. 2 March 2011(first observation only) 2011 ES 4 P1154IU (NEOCP 2020) Apollo NEO 31 May 2020 (JD 2459000.5) 1 9.54 yr (3,485 days) 0.000630 AU km on 3.681 AU 1.3548 AU 0.8260 AU 1.0904 AU 0.24248 1.14 yr (415.9 days) 3.3735° 339.890° 337.252° 273.568° 22 - 49 m (CNEOS) ~25 m on 25.4 2011 ES 4 is an Apollo near-Earth asteroid roughly 22 - 49 m ft 2 off us in diameter. It was first observed on 2 March 2011 when the asteroid was about 0.054 AU km mi on from Earth and had a solar elongation of 159 degrees. It passed closest approach to Earth on 13 March 2011. Before the 2020 approach, the asteroid had a short observation arc of 4 days and had not been observed since March 2011. The asteroid was expected to pass within 1 lunar distance of Earth in early September 2020, but did not. There was no risk of a 2020 impact because the line of variation (LOV) did not pass through where Earth would be, and the closest possible 2020 Earth approach was about 0.00047 AU km mi on. One line of variation showed the asteroid passing closest to Earth on 5 September 2020 at 0.06 AU km mi on with a magnitude of 23, which would place it near the limiting magnitude of even the best automated astronomical surveys. 2011 ES 4 was recovered as P1154IU on 5 September 2020 at apparent magnitude 18. It passed 0.009886 AU LD km mi on from Earth on 2 September 2020. With the observation arc being extended to 9 years, it was removed from the Sentry Risk Table on 6 September 2020. 2019 NEODyS and JPL Horizons show the asteroid came to opposition (opposite the Sun in the sky) around 8–13 December 2019 at around apparent magnitude 24.8. (Magnitude 24.8 is about 30 times fainter than the more common magnitude 21 detected by automated Near-Earth object surveys.) During opposition, the uncertainty in the asteroid's sky position covered about 3.8 degrees of the sky. 2020 On 2 September 2020 the asteroid passed 0.009886 AU LD km mi on from Earth and was recovered as P1154IU at apparent magnitude 18 on 5 September 2020. Prior to its recovery in 2020, 2011 ES 4 had a short 4-day observation arc. Around 1 September 2020 (±8 days),sbdb-date it was expected to pass about 0.0008 AU km mi on from Earth but could also pass as far away as 0.11 AU km mi on, which could make it much fainter and harder to spot again (recover). It could have been around magnitude 22–24 with recovery efforts challenged by the brightness of a 2 September full Moon. Opposition from the Sun did not occur until mid-September. There was no risk of impact as the line of variation (LOV) did not pass through where Earth would be, which computed a closest possible approach of 0.00047 AU km mi on. JPL Horizons predicted the asteroid to be hidden in the Sun's glare until hours before closest approach. NEODyS did not expect the asteroid to be more than 50 degrees from the Sun until 30 August. 2055 With a 9-year observation arc it is known that the asteroid will be 2.1 AU km mi on from Earth on 2 September 2055 (with an uncertainty of ±10 thousand km) and therefore there is no risk of an impact. When there was only a short 4-day observation arc, the Sentry Risk Table showed an estimated 1 in 67000 chance of the asteroid impacting Earth on 2 September 2055. The nominal JPL Horizons 2 September 2055 Earth distance was estimated at 0.8 AU km mi on with a 3-sigma uncertainty of ±40 trillion km. (Due to the short 4-day observation arc, between 2011 and 2055 the uncertainty region grew to wrap around the entire orbit so the asteroid could be anywhere on any of the numerous orbit fits.) With a diameter between the 20-meter Chelyabinsk meteor and the 50-meter Tunguska event,volume 2011 ES4 has the potential to do structural damage to a city since asteroids around a diameter of 40 meters can cause wood-frame buildings to collapse. However, as there are numerous variables, the actual effect of an impact might be similar to the smaller of these two events with widespread injuries and damage to buildings if it occurred over a populated area. At 25 meters in diameter it would be a blast equivalent to the high altitude air detonation of a nuclear weapon of around half a megaton yield.yield 2121 Around 3 September 2121 (±2 days), it is expected to pass between 0.0007 AU LD km mi on and 0.04 AU km mi on from Earth. Notes sbdb-date With a 4 day observation arc, the JPL Small-Body Database for 2020-Sep-01 showed the "Time Uncertainty" as 8_00:08 which is 8 days, 0 hours, and 8 minutes. volume Assuming the same density and given that the volume of a sphere , based on a diameter of 22–49 meters, 2011 ES4 would have a volume of 5600–62000 m3. The larger estimate would be ~10 times more massive. yield The impact energy for 2011 ES4 at an assumed diameter of 25 meters is 450kt. The impact energy of the Chelyabinsk meteor (with a diameter estimated between 15–25 meters) was measured at 440kt by nuclear test ban sensors. References MPEC 2011-E13: 2011 ES4 IAU Minor Planet Center 2011-03-03 https://minorplanetcenter.net//mpec/K11/K11E13.html 2019-05-01 (K11E04S) MPEC 2020-R18 : 2011 ES4 IAU Minor Planet Center 2020-09-06 https://www.minorplanetcenter.net/mpec/K20/K20R18.html 2020-09-06 Earth Impact Risk Summary: 2011 ES4 NASA/JPL Near-Earth Object Program Office https://cneos.jpl.nasa.gov/sentry/details.html#?des=2011%20ES4 https://archive.today/20190509174235/https://cneos.jpl.nasa.gov/sentry/details.html%23?des=2011%20ES4 2019-05-09 live 2019-05-01 last observation: 2011-03-06; arc: 4 days JPL Small-Body Database Browser: (2011 ES4) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2011ES4;cad=1 Jet Propulsion Laboratory https://web.archive.org/web/20200831221119/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2011ES4&cad=1 2020-08-31 live 2019-05-01 JPL CNEOS Fireball and Bolide Data https://cneos.jpl.nasa.gov/fireballs/ Jet Propulsion Laboratory 2020-09-05 2011ES4 Ephemerides for December 2019 NEODyS (Near Earth Objects Dynamic Site) https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2019&m0=12&d0=1&h0=0&mi0=0&y1=2019&m1=12&d1=25&h1=0&mi1=0&ti=1.0&tiu=days https://web.archive.org/web/20190502155642/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2019&m0=12&d0=1&h0=0&mi0=0&y1=2019&m1=12&d1=25&h1=0&mi1=0&ti=1.0&tiu=days 2019-05-02 live 2019-05-01 2011ES4 Ephemerides for September 2020 NEODyS (Near Earth Objects Dynamic Site) https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2020&m0=8&d0=20&h0=0&mi0=0&y1=2020&m1=9&d1=30&h1=0&mi1=0&ti=1.0&tiu=days https://web.archive.org/web/20190502155812/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2020&m0=8&d0=20&h0=0&mi0=0&y1=2020&m1=9&d1=30&h1=0&mi1=0&ti=1.0&tiu=days 2019-05-02 live 2019-05-01 Archive: 2011ES4 Ephemerides for September 2020 NEODyS (Near Earth Objects Dynamic Site) https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2020&m0=8&d0=20&h0=0&mi0=0&y1=2020&m1=9&d1=30&h1=0&mi1=0&ti=1.0&tiu=days https://web.archive.org/web/20190502155812/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2020&m0=8&d0=20&h0=0&mi0=0&y1=2020&m1=9&d1=30&h1=0&mi1=0&ti=1.0&tiu=days dead 2019-05-02 2019-05-02 2011ES4 Ephemerides for 2 September 2055 NEODyS (Near Earth Objects Dynamic Site) https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2055&m0=9&d0=1&h0=0&mi0=0&y1=2055&m1=9&d1=6&h1=0&mi1=0&ti=1.0&tiu=days https://web.archive.org/web/20190502155848/https://newton.spacedys.com/neodys/index.php?pc=1.1.3.1&n=2011ES4&oc=500&y0=2055&m0=9&d0=1&h0=0&mi0=0&y1=2055&m1=9&d1=3&h1=0&mi1=0&ti=1.0&tiu=days 2019-05-02 live 2019-05-01 2011 ES4 found! https://groups.io/g/mpml/message/35826 Piero Sicoli 6 September 2020 24 September 2020 Re: 2011 ES4 possible recovery effort Bill J. Gray 2020-08-31 https://groups.io/g/mpml/message/35816 2020-08-31 Earth Impact Effects Program: 40-meter asteroid @ 14 km/s Robert Marcus H. Jay Melosh Gareth Collins https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=0.0001&distanceUnits=2&diam=0.040&diameterUnits=2&pdens=&pdens_select=2600&vel=14&velocityUnits=1&theta=90&wdepth=&wdepthUnits=1&tdens=2750 2020-09-05 Pseudo-MPEC for P1154IU Project Pluto https://www.projectpluto.com/neocp2/mpecs/P1154IU.htm#elements https://web.archive.org/web/20200906061735/https://www.projectpluto.com/neocp2/mpecs/P1154IU.htm 2020-09-06 live 2020-09-06 Observer Table for Asteroid (2011 ES4) Soln.date: 2020-Sep-08 Horizons output https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2011ES4 2020-09-08 (Table Settings: 39. Range (RNG_3sigma is ±km)Time Span: 2055-09-02) External links 2011+ES4 2011ES4 3558279 # Category:Minor planet object articles (unnumbered) Category:Discoveries by MLS Category:Near-Earth objects removed from the Sentry Risk Table 20200902 20110302