Astronomy

Discovery of Near Earth Objects (NEO's)

Discovery of Near Earth Objects (NEO's)



We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Near Earth Objects (NEO's) have been mapped by NASA and JPL since 1990's. The graph below shows how many of these potential planet-killers have been found and classified over the years. I am curious as to why there have been so many more 140 meter to 1 km NEO's discovered, as opposed to NEO's with a diameter of 1 km or more. I think it is as simple as there are just more "smaller" objects left over from the formation of the solar system? Am I correct in saying this, or are there deeper astronomical processes at play here?


This is because there are many more small NEOs than there are large ones and the larger ones are easier to find and so were found first. The numbers of NEOs follow what's know as a power law distribution with an exponent of ~1.75. This means that given the roughly factor 7 difference between 140m and 1000m NEOs, there will be 7^1.75 = ~31 times as many 140m NEOs as 1000m NEOs. This is shown in this plot below. We estimate there are about 950 NEOs 1km or larger and about 25,000 NEOs larger than 140m. We have found over 93% of the 1+km NEOs and so there aren't many left to find. In comparison, over 2/3rds of the 140-1000m NEOs still remain to be found, most in the 140-300m size range. However this improved considerably since even 2010 when about 82% of the population was still to be found.


Near-Earth object

Near-Earth objects (NEO) are asteroids, comets and large meteoroids whose orbit intersects Earth's orbit and which may therefore pose a collision danger.

Due to their size and proximity, NEOs are also more easily accessible for spacecraft from Earth and are important for future scientific investigation and commercial development.

In fact, some near-Earth asteroids can be reached with a much smaller change in velocity than the Moon.

In the United States, NASA has a congressional mandate to catalogue all NEOs that are at least 1 kilometer (0.6 miles) wide.

At this size and larger, an impacting NEO would cause catastrophic local damage and significant to severe global consequences.

Approximately 800 of these NEOs have been detected.

According to the most widely accepted estimates, there are still 200 more that have not been found yet.

The United States, European Union and other nations are currently scanning for NEOs in an effort called Spaceguard.

Currently efforts are under way to use an existing telescope in Australia to cover the approximately 30 percent of the sky that is not currently surveyed.


Impact: Detection of Near Earth Objects and Preventing a Collision

There are thousands of asteroids and comets orbiting throughout the solar system right now. Those that travel close to Earth are known as Near Earth Objects or NEOs. A vast majority of these extra-terrestrial objects pose no threat to life on Earth, but at times these bodies drift into Earth’s vicinity and become a cause for concern. There are many programs aimed at the detection of these Near Earth Objects with the hopes of discovering threats with ample time to avoid catastrophe. Detection is the first step towards prevention, and as such the hunt for NEOs begins with an exploration of past and present detection programs, and a consideration of proposed future programs and technologies. The available preventative measures are hypothetical at this stage, but they generally focus on deflection systems. Should a NEO become a danger to Earth, its trajectory could be changed using one of the examined deflection techniques, safeguarding life as we know it. Better detection will result in more proactive and preventative measures to counter against devastating collisions.

Near Earth Objects: What are they?

To better understand Near Earth Objects and the subsequent discussion, the following terminology will be helpful.

Comets: Space objects made of frozen gases, rocks and dust, sometimes referred to as "frozen snowballs." 1

Asteroids: Space objects of various sizes made of rocks and metals that are too small to be considered planets. 2

Near Earth Object or NEOs refers to comets or asteroids with orbits that enter Earth’s neighbourhood. More specifically, these comets or asteroids are at a distance of less than 1.3AU or 19,477,323 km, at the point of orbit closest to the sun. 3 Many NEOs are asteroids. 3

When a NEO is an asteroid it is referred to as a Near Earth Asteroid or NEA. These NEAs are separated into three groups based on the NEAs distance to the sun 3 , as seen in Figure 1.

Potentially Hazardous Objects or PHOs are asteroids, and less often comets, that are significantly large and close enough to Earth to pose a serious threat of collision. NEOs with orbits that come within 0.05 AU to Earth and are at least 150 m in diameter are considered threatening. 4

Figure 1: Sub classification of Near Earth Asteroids. Alan Chamberlin

How are Near Earth Objects Detected?

The location of Near Earth Objects like NEAs is of great importance to humans. While there is a low probability of a large NEA impacting Earth, the consequences of such an impact are very high. 5 It is critical that threats are detected years before getting close to Earth. 6 Detection is the first step in preventing an impact with Earth.

Figure 2: Near Earth Asteroid Discoveries, By Survey Type, By Year
Alan Chamberlin

The three most successful discovery survey programs (i.e detection programs) for NEAs since 1995 are the LINEAR Program, The Catalina Sky Survey and Pan-STARRS, where the latter two account for 90% of new NEO discoveries. 26

Less influential but still important are Spacewatch, NEOWISE, NEAT, and LONEOS. 7 These programs will be discussed below.

In 2005, NASA was tasked with detecting 90% of Near-Earth objects with a size greater than 140 meters in diameter by the year 2020. 8

Why use infrared telescopes?

When observing the night sky from here on Earth, either with the naked eye or with an optical telescope, bright stars and planets are seen easily, even the occasional asteroid or comet is observed given they have a reflective enough surface. When the goal is to find dim, less reflective NEOs, bright stars outshine objects of interest in the visual wavelengths of the energy spectrum, however, thermal radiation in the infrared spectrum is readily emitted. 27 As the name suggests, infrared telescopes scan in the infrared band of the electromagnetic spectrum 27 , thus making them ideal for detecting NEOs while ignoring visually bright stars. Infrared telescopes are essential to NEO detection efforts. Often, comets and asteroids are initially detected by infrared telescopes, which then have follow-up observations performed by ground-based optical telescopes. 27

Current Principle Discovery Programs

The Lincoln Near-Earth Asteroid Research (LINEAR) program is funded by the United States Air Force and NASA and is comprised of two one-meter Ground-Based Electro-Optical Deep Space Surveillance (GEODSS) telescopes located at Lincoln Laboratory Experimental Test Site in Socorro, New Mexico, USA. 9 LINEAR is a new application for technology originally used to detect Earth-orbiting satellites. 9 Since its inception in 1998, LINEAR has contributed to the detection of many NEOs. 9 Major changes to the system were needed to catalogue more asteroid populations of smaller sizes (down to 140m) which was accomplished in 2014 when the LINEAR program was successfully transitioned from two 1-m telescopes to a 3.5-m wide-field-of-view Space Surveillance Telescope (SST) at the Atom Site on White Sands Missile Range, New Mexico. 9

The Catalina Sky Survey (CSS) began operating in April 1998 at Mt. Lemmon Observatory and in 2013, the program added a second reflecting telescope at the same location. 12 CSS is very accurate at detecting NEOs in 2012 the program was responsible for the detection of more than 625 NEOs. 12 The success can be partly accredited to the wide-ranging sky coverage, and the subsequent follow-up observations, made by the Mt. Lemmon telescope. The CSS’s success in detection has contributed to making it more popular as its exploration progressed. This popularity has added to its importance in detecting NEOs.

The Panoramic Survey Telescope and Rapid Response System or Pan-STARRS was developed at the University of Hawaii Institute for Astronomy and full-time, continuous, scientific observations began May 13, 2010. 8 Discovering and characterising PHOs is the main goal of Pan-STARRS and it is able to detect objects 100 times fainter than other detection programs. 8

Pan-STARS at sunset
Forest Starr and Kim Starr

Additional Programs

NEOWISE is an infrared space telescope funded by NASA’s planetary science division and is the asteroid detection specific portion of NASA’s WISE program. 14 In December 2013, NEOWISE was brought out of hibernation to aid in the detection of PHOs. 14 Currently, NEOWISE is about 70% of the way through its sixth coverage of the entire sky. 14

This artist's concept shows the Wide-field Infrared Survey Explorer, or WISE spacecraft, in its orbit around Earth.
NASA/JPL-Caltech

LONEOS or The Lowell Observatory Near-Earth-Object Search has the capability to scan the entire assessable sky every month and is located in Flagstaff, Arizona. 13 It consists of a 0.6m fully-automated Schmidt telescope and CCD camera imaging device capable of recording asteroids and stars 150,000 times fainter than can be seen with the human eye in just one minute of exposure. 13

The Near Earth Asteroid Tracking (NEAT) began in December 1995 and ran observations every month until 2007. The system operated autonomously at the Maui Space Surveillance Site on the summit of the extinct Haleakala Volcano Crater, Hawaii. 11 While the program was discontinued in 2007 28 , NEAT contributed 26,000 detections of main-belt asteroids. 11

Spacewatch began in 1983 under the counsel of Tom Gehrels. The 0.9m f/5 Newtonian telescope was the backbone of the first lengthy CCD discovery program. 10 Spacewatch was the first program to discover a NEO using automated image processing software and was also the original program to utilise CCD technology in the discovery of NEOs. 10 Through 2008, Spacewatch gradually shifted their emphasis from NEO detections to follow-up observations that are critical for securing accurate orbits and monitoring numerous small object populations. Additionally, the focus of Spacewatch has also spread to the detection of potential interplanetary space missions. 10

Future Programs

Announced in 2012, the Sentinel Space Telescope will be designed and built for the B612 Foundation which is dedicated to protecting Earth from dangerous asteroid impacts. The Sentinel is an infrared telescope with a tentative launch date in 2019 and is being designed to locate 90% of known asteroids greater than 140 m in diameter in near-Earth orbits. 15

Large Synoptic Survey Telescope (LSST) began construction in August 2014 and is expected to be completed by 2019. Its design is a large-aperture wide-field, ground-based telescope that will survey half the sky every few nights. The design will use three mirrors instead of the

Three-dimensional rendering of the baseline design for the LSST
LSST

conventional two in order to produce a very wide, undistorted field of view. Once completed, the telescope will potentially be able to detect asteroids as small as 140 m in diameter and as far away as the Main Belt asteroids. It is projected to detect 60-90% of potentially hazardous asteroids larger than 140 m. 16

How Dangerous are Asteroids?

Of the Near Earth Objects detected, few are actually of any threat to life on Earth. Threatening asteroids, i.e. PHOs, are classified as being approximately 20m to 500m in diameter. 23 Currently, no serious risk to Earth has been detected for the next 100 years or so, however, new smaller potentially harmful objects are still being discovered. 3 The most efficient, safe, and energy efficient strategy against a short warning PHO is to divert it from its trajectory. 23 Diversion is the preferred mitigation technique because destruction would result in the dispersal of asteroid fragments leading to a larger number of possible PHOs with unpredictable trajectories. 23 The deflection option depends on the time to impact, as well as the size, type, composition, and the trajectory of the PHO that is approaching Earth.

As suggested above, the chances of a large PHO striking Earth is very unlikely, but the repercussions are far reaching. 21 Often, the object burns up in Earth’s atmosphere, but occasionally, large enough objects (i.e larger than 20m 23 ) enter Earth's atmosphere and make an impact with Earth. Even if the meteor doesn’t make an impact with Earth or is relatively small, the energy released is comparable to that of an atomic bomb, 17 such as that seen in Chelyabinsk, Russia in 2013. It is estimated that the meteor that impacted in Chelyabinsk “exploded with the energy of 500 Kilotonnes”. 18 For comparison, the atomic bombs dropped on Hiroshima and Nagasaki only had an energy equivalent of 16 Kilotonnes. 19 If the object is large enough, the devastation would be imminent. The Chicxulub Crater, located in the Yucatan Peninsula of Mexico, is an estimated 65 million years old. 20 Officially discovered some 30 years ago, it is thought to be responsible for the eventual extinction of many species, including the dinosaurs. 17

Impact: Detection to Deflection

The Roadmap for Earth Defense Initiatives (READI Project) is a planetary defence project created during the International Space University Studies Program in 2015. It creates ‘roadmaps’, or plans, for space agencies, governments, and the general public, to deal with astronomical emergencies in situations where PHOs cannot be destroyed due to short warnings. 21

Artist's impression of a 1000km-diameter planetoid hitting a young Earth.
Don Davis (work commissioned by NASA)

READI Consists of five elements of Planetary Defense 21 :

  • Detection of PHOs followed by a tracking phase
  • Deflection of PHOs via thermonuclear devices (TED) and the Directed Energy System (DES) the safest and most efficient means of PHO impact prevention
  • Global Collaboration where new norms, legal actions, and an advisory body are implemented into the Planetary Defense Program for imminent impact threats
  • Outreach and Education to better educate and increase the interest in Planetary Defense amongst children and students
  • Evacuation and Recovery strategies that target different situations and threat characteristics according to the type of asteroid and comet impact response

READI mainly focuses on deflection and disruption methods against PHOs and approaches the problem of an incoming PHO with a warning period of approximately two years from detection to impact with Earth. 21 This page discusses detection, deflection, and a few points concerning global collaboration. Readers interested in outreach and education, and evacuation and recovery strategies are encouraged to read Architecture for Mitigating Short-Term Warning Cosmic Threats: READI Project.

Artist’s conception of a fragmented asteroid
NASA/JPL-Caltech

Currently, the various deflection mechanisms proposed are not cost-effective enough to be feasibly implemented as a mitigation strategy against cosmic threats. However, some of these techniques have shown promising results in their hypothetical abilities to divert PHOs. 17 These deflection mechanisms include Thermonuclear Devices, Directed Energy Systems, and Kinetic Impactors.

Kinetic Impactor works by sending one or more large, fast moving spacecraft to intersect the path of approaching NEOs. The proximity and mass of the spacecraft will exert a gravitational attraction which can change the trajectory of the NEO, deflecting it away from Earth’s orbital path. 25 Advanced warning would be needed to implement a kinetic impactor, approximately 1 – 2 years of warning would be necessary for small asteroids and upwards of 10 years would be necessary deflect a large (100+ km diameter) object. 25 This may not be effective in changing the orbits of the larger objects due to the amount of energy needed to do so.

Photo from the Deep Impact Mission where a kinetic impactor was used to gather data about a comet. This would be the type of impactor proposed to divert NEOs.
Courtesy of NASA

Directed Energy Systems (DES) would utilise laser energy to essentially vaporise a PHO’s materials, either abolishing them or using the ablation to change the object's trajectory. 24 It is a proposed system that is currently applied for military use, and hypothetically, could deflect all known threats with sufficient warning. 24 Two classifications of laser systems exist, DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) and DE-STARLITE(Directed Energy System for Targeting of Asteroid and exploration LITE). DE-STAR, also known as “stand-off” modular phased arrays, would focus kilowatt class lasers on PHOs with the purpose of vaporising the object. 24 DE-STARLITE would be a smaller “stand-on” system stationed on a modest spacecraft while moving in accordance with the asteroid. It is a lengthier process and more mobile than the DE-STAR system which would remain situated within Earth’s orbit. 24

Thermonuclear devices (TND) are weapons that use heat or nuclear power as their source of energy. As the name indicates, the main goal is to use this nuclear energy to change the direction of the trajectory of a PHO so that it does not collide with Earth. There is evidence that nuclear weapons can be efficient in protecting Earth from PHOs 22 , but the size of the object would be a limiting factor. A small enough object could be diverted by nuclear weapons, but for larger objects, it would be harder to get the amount of nuclear power needed to divert them. 22

A depiction of Excalibur, an interspace Thermonuclear Device for missile defence, firing on a single object. Similar technology is proposed to divert PHOs.
Courtesy U.S Airforce

Moving Forward

Humans have an ethical obligation to prevent harm when and where it is possible to do so, and as such the appropriate thing to do is be prepared for an impact with a PHO. Detection of NEOs is and always will be step one of the moderation process. Without detection, there is no chance of mitigation. By 2020, detection of objects larger than 140m is to be completed by NASA programs, adding to the ability to defend the Earth from an impact. Moving forward, more educational materials need to be made available to the public, and hopefully, this site can aid in that goal. Further global warning systems and disaster plans need to be negotiated internationally, and short-term mitigation systems need to researched and tested, as touched on in the discussion of the READI Program. As life on Earth advances, so should the interest in preserving that life from both threats here on Earth and those existing in the vastness of space.

Artist's depiction of a collision between two planetary bodies. Such an impact between the Earth and a Mars-sized object likely formed the Moon.
NASA/JPL-Caltech


Near Earth Objects (NEO): Earth's Upcoming Close Approaches with Asteroids

NEOs (Near Earth Objects) are a category of Asteroids whose orbit is very close to intersecting Earth's orbit. These objects are tracked carefully by astronomers because of potential risk of impact.

The table below is updated multiple times per day and lists all the known upcoming close approaches between the Earth and NEO asteroids that will be closer than 5 Lunar Distances and will happen in the next 10 years.

  • close approach distance is less than 2 Lunar Distances
  • close approach distance is less than 1 Lunar Distances
  • close approach distance is less than 0.5 Lunar Distances

Asteroid Name Date and Time of Closest Approach (UT) Close Approach Distance Approach Relative Speed km/s
Kilometers (km) Lunar Distance (LD) Astronomical Units (AU)
2021 LL6 2021-Jun-18 11:50 1,681,357 4.37322 0.01124 9.89
2021 LU8 2021-Jun-20 05:42 1,258,553 3.27351 0.00841 10.04
2021 LE4 2021-Jun-21 05:04 1,784,370 4.64116 0.01193 13.77
2021 LV2 2021-Jun-26 20:35 1,777,153 4.62239 0.01188 7.42
2021 ME1 2021-Jun-27 12:20 1,802,149 4.68740 0.01205 8.54
2010 XJ11 2021-Jul-01 16:35 1,555,565 4.04603 0.01040 16.37
2020 AD1 2021-Jul-04 06:47 1,086,842 2.82688 0.00727 4.85
2021 MC 2021-Jul-06 06:30 1,133,384 2.94794 0.00758 7.15
2019 AT6 2021-Jul-13 07:34 1,620,776 4.21565 0.01083 5.15
2016 BQ 2021-Aug-14 14:35 1,677,856 4.36412 0.01122 4.70
2019 XS 2021-Nov-09 03:48 573,912 1.49275 0.00384 10.68
2020 AP1 2022-Jan-07 17:32 1,743,802 4.53564 0.01166 5.65
2018 CW2 2022-Feb-18 09:20 857,753 2.23102 0.00573 10.76
2020 DC 2022-Mar-06 09:17 1,487,341 3.86858 0.00994 4.94
2016 FZ12 2022-Mar-19 11:39 826,060 2.14859 0.00552 8.31
2020 SQ 2022-Mar-21 16:38 1,047,411 2.72432 0.00700 6.02
2017 UK52 2022-Apr-29 16:26 1,009,297 2.62519 0.00675 13.72
2019 JE 2022-May-11 03:56 1,886,187 4.90598 0.01261 7.22
2012 UX68 2022-May-15 15:45 1,053,657 2.74057 0.00704 8.20
2021 KO2 2022-May-30 04:32 1,069,478 2.78172 0.00715 14.78
2020 TO2 2022-Oct-16 06:39 877,581 2.28259 0.00587 12.47
2004 UT1 2022-Oct-29 07:55 1,518,997 3.95092 0.01015 6.35
2020 WD 2022-Nov-08 21:55 1,254,486 3.26293 0.00839 5.97
2018 WH 2022-Nov-16 19:27 959,055 2.49451 0.00641 7.73
2005 LW3 2022-Nov-23 10:06 1,139,790 2.96460 0.00762 13.49
2019 XY 2022-Dec-10 06:00 1,359,702 3.53659 0.00909 12.89
2015 RN35 2022-Dec-15 08:11 686,053 1.78443 0.00459 5.91
2013 YA14 2022-Dec-25 12:52 1,033,851 2.68905 0.00691 10.47
2010 XC15 2022-Dec-27 18:15 772,003 2.00798 0.00516 10.10
2014 LJ 2023-Jan-14 03:33 1,819,585 4.73275 0.01216 3.48
367789 2023-Feb-03 08:50 1,817,084 4.72625 0.01215 9.92
2020 OO1 2023-Feb-04 20:35 1,844,228 4.79685 0.01233 7.74
2020 DG4 2023-Feb-17 19:06 636,051 1.65437 0.00425 6.88
2020 UQ3 2023-Jul-18 11:01 1,200,452 3.12238 0.00802 9.29
2016 LY48 2023-Sep-17 21:38 1,665,546 4.33210 0.01113 11.05
2013 TG6 2023-Sep-28 21:33 1,366,197 3.55349 0.00913 4.15
1998 HH49 2023-Oct-17 00:34 1,174,203 3.05411 0.00785 14.79
2019 CZ2 2023-Nov-25 19:49 1,072,024 2.78834 0.00717 5.83
2020 YO3 2023-Dec-23 20:28 1,363,898 3.54751 0.00912 16.62
2021 JW2 2024-Apr-19 08:53 623,093 1.62067 0.00417 5.09
2017 SA20 2024-Apr-19 09:48 1,464,211 3.80842 0.00979 6.19
2020 GE 2024-Sep-24 04:54 660,118 1.71697 0.00441 2.22
2018 QE 2024-Oct-09 04:03 668,092 1.73771 0.00447 4.40
2016 VA 2024-Nov-01 22:52 565,473 1.47080 0.00378 21.17
2020 UL3 2024-Nov-12 12:28 1,565,131 4.07092 0.01046 10.46
2006 WB 2024-Nov-26 18:00 891,380 2.31849 0.00596 4.20
2007 XB23 2024-Dec-11 18:08 445,628 1.15908 0.00298 4.77
2012 PB20 2025-Feb-09 20:05 1,427,896 3.71397 0.00954 4.27
2021 FH1 2025-Mar-21 14:08 1,495,654 3.89021 0.01000 13.83
2015 XX168 2025-Dec-18 20:34 1,804,028 4.69229 0.01206 11.55
2015 VO142 2026-Mar-17 05:12 1,043,801 2.71493 0.00698 3.09
2010 RA91 2026-Mar-22 01:13 1,795,585 4.67033 0.01200 9.89
2013 GM3 2026-Apr-14 16:15 260,528 0.67764 0.00174 7.41
2003 LN6 2026-Jun-18 20:53 1,417,073 3.68582 0.00947 3.92
2015 TS238 2026-Oct-08 17:12 1,813,910 4.71799 0.01213 15.81
2019 XF2 2026-Dec-04 00:35 1,189,881 3.09489 0.00795 10.20
2010 VQ 2026-Dec-13 05:24 1,192,916 3.10278 0.00797 4.44
2015 DG200 2027-Jan-22 10:21 1,324,616 3.44533 0.00885 20.01
2016 VO1 2027-Feb-14 19:13 1,416,497 3.68432 0.00947 13.72
137108 2027-Aug-07 07:11 389,908 1.01415 0.00261 26.28
2019 DP 2027-Aug-30 08:30 631,973 1.64377 0.00422 8.96
2006 SB 2027-Sep-19 13:29 1,524,006 3.96395 0.01019 9.73
2018 FK5 2027-Oct-04 00:14 1,714,665 4.45986 0.01146 11.59
2020 SN6 2027-Oct-04 01:28 1,413,957 3.67771 0.00945 5.26
2019 WV 2027-Nov-14 00:16 1,690,534 4.39709 0.01130 5.18
2020 XF 2027-Dec-02 06:18 708,606 1.84309 0.00474 3.54
2020 AW 2028-Jan-19 06:16 1,623,075 4.22163 0.01085 4.95
2021 CD 2028-Jan-29 02:49 1,588,731 4.13230 0.01062 9.35
2019 EF1 2028-Mar-08 18:47 1,775,946 4.61925 0.01187 6.07
2009 WR52 2028-May-20 12:11 757,825 1.97111 0.00507 5.63
153814 2028-Jun-26 05:23 248,714 0.64691 0.00166 10.24
2011 LJ19 2028-Jul-25 18:27 1,272,068 3.30866 0.00850 9.80
35396 2028-Oct-26 06:44 929,244 2.41697 0.00621 13.92
2015 VL64 2028-Nov-02 19:17 1,000,968 2.60352 0.00669 8.53
2017 VN2 2028-Nov-20 04:26 1,578,001 4.10439 0.01055 5.53
2012 XE133 2028-Dec-30 09:19 1,475,570 3.83797 0.00986 9.65
2016 EP84 2029-Jan-03 08:23 1,911,279 4.97125 0.01278 2.84
2019 BX1 2029-Jan-08 14:59 445,276 1.15817 0.00298 4.10
2019 BE5 2029-Jan-27 18:09 1,646,630 4.28289 0.01101 13.96
292220 2029-Jan-28 04:24 1,225,427 3.18734 0.00819 4.90
2017 GK6 2029-Apr-03 21:49 1,788,286 4.65134 0.01195 10.28
2007 WA 2029-May-13 11:42 1,792,616 4.66261 0.01198 5.11
2000 SL10 2029-May-13 22:57 1,785,236 4.64341 0.01193 8.49
2006 HE2 2029-Sep-30 01:00 1,582,789 4.11684 0.01058 4.77
2001 AV43 2029-Nov-11 15:24 313,057 0.81426 0.00209 4.00
2016 VY1 2029-Nov-12 18:59 1,005,052 2.61415 0.00672 6.11
2020 YB1 2029-Dec-24 23:06 785,545 2.04321 0.00525 11.70
2021 BB 2030-Jan-14 09:44 1,795,775 4.67082 0.01200 5.42
2019 BE5 2030-Feb-17 23:36 1,604,489 4.17329 0.01073 13.88
2016 JD18 2030-May-18 12:24 1,824,755 4.74620 0.01220 14.60
2019 CL2 2030-Jul-02 00:23 991,864 2.57984 0.00663 7.96
2014 YN 2030-Nov-11 06:43 1,283,650 3.33878 0.00858 3.14
2015 XH55 2030-Nov-28 23:16 1,058,018 2.75191 0.00707 7.20
2021 DG 2031-Feb-19 12:01 1,101,887 2.86602 0.00737 12.75
2020 KQ4 2031-May-24 07:43 1,431,050 3.72217 0.00957 4.59


Asteroids Galore! 10,000th Near-Earth Object Discovered

A telescope in Hawaii built to seek out asteroids that might one day threaten the Earth has discovered the 10,000th near-Earth space rock ever seen.

The powerful Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) caught sight of the 1,000-foot-wide (300 meters) asteroid 2013 MZ5 on June 18. The large rock poses no danger to Earth, researchers said.

"The first near-Earth object was discovered in 1898," Don Yeomans, the manager of NASA's Near-Earth Object (NEO) Program Office, said in a statement. "Over the next hundred years, only about 500 had been found. But then, with the advent of NASA's NEO Observations program in 1998, we've been racking them up ever since. And with new, more capable systems coming on line, we are learning even more about where the NEOs are currently in our solar system, and where they will be in the future." [See Images of Potentially Dangerous Asteroids]

While 10,000 is a big number, there are many more close-flying space rocks still out there waiting to be found. Scientists estimate that near-Earth space hosts millions of asteroids, some of which could pose a danger to our planet down the road.

"Finding 10,000 near-Earth objects is a significant milestone," Lindley Johnson, program executive for NASA's Near-Earth Object Observations Program, said in a statement. "But there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth."

Near-Earth objects come in all shapes and sizes. Asteroids and comets are labeled NEOs if they come within about 28 million miles (45 million kilometers) of Earth's orbital distance, according to NASA officials.

Some NEOs are only a few feet long, while others are miles across. The largest known NEO is the asteroid 1036 Ganymed, which is about 25 miles (41 km) long. Most NEOs are smaller than 0.6 miles (1 km), according to NASA scientists. About 30 percent of the estimated 15,000 NEOs that are 460 feet (140 m) in size have been catalogued, but less than 1 percent of the more than 1 million NEOs that are about 100 feet (30 m) in diameter have been found, NASA estimates.

Larger near-Earth asteroids and comets are less common than smaller objects that could give the planet a close graze, NASA officials said.

About 10 percent of the 10,000 discovered NEOs are larger than 3,300 feet (1 km) in size. If one of these large objects were to impact the Earth, it could create global problems. However, none of the larger asteroids are in danger of impacting the Earth, according to NASA. So far, NASA scientists have discovered more than 90 percent of these mountain-size space rocks.

The Pan-STARRS-1 telescope seeks out near-Earth objects from the peak of the Haleakala volcano on Maui. The telescope began its asteroid hunt in 2010 and has been billed as the world's most powerful digital camera.


The IAU and Near Earth Objects

From time to time, we have all seen stories in the Press about Near Earth Objects that are about to hit the Earth on some date in the not-too-distant future. Sometimes the IAU is mentioned in the story. The aim here is to briefly describe what the normal practice is when a NEO is discovered and what part the IAU might be seen to play in this process. In fact, the basic procedure is the same whether the discovery is of a comet, a Kuiper belt object, a Main belt asteroid or any other minor body in the Solar System. When an observer discovers a body that is moving relative to the background, the information is always sent to the IAU Minor Planet Center (MPC) located at the Smithsonian Astrophysical Observatory in Cambridge, MA, USA. This information should always give the position of the body (Right Ascension and Declination) and the time of the observation (using UT) for each observation made. Most observers will try to obtain at least three such sets of observations during the night. Though observers may try to derive an orbit for the object from their observations, this orbit is not usually sent to the MPC, the orbit that is made public comes from calculations made at the MPC. With data from a single night, only the crudest of orbits can be determined. Mostly, the initial discoverers have further nights scheduled at the telescope, or know of colleagues who have telescope time, so that additional observations of the body come about as a matter of course. This usually is sufficient information to allow the MPC to generate a reasonable orbit and the discovery is announced, in general as part of the MPC Electronic Circular system. In order to obtain a more reliable orbit, further observations, well separated in both space and time from the discovery observations are required. For most bodies in the Solar System, these observations are obtained as part of other programmes, usually on a time scale of months, and this is perfectly adequate to allow the body to be permanently recorded.

The initial discoverers may, for a number of reasons, be unable to obtain additional observations themselves. To aid the process of obtaining additional observations, the MPC produces a list that is generally available of objects that need further observations and are currently visible so that observers with telescope time can make a special effort to observe these objects, thus ensuring that the elements of the orbit are secure. The Near Earth Objects are peculiar in that they are far easier to detect when close to the Earth and thus appear to move very fast against the background and, unless additional observations are obtained very quickly, the body may be lost. In this event, the MPC may become pro-active and solicit observations from known observers, or release a preliminary orbit, with large error bars, so that other observers will know roughly where on the sky this particular object is so that they can conduct a search for it. Sometimes it is found in archival records.

The problem that I alluded to in the first sentence appears when predictions for the future motion of the body, based on the rather poor initial orbit, indicate that collision with the Earth is a very remote possibility sometime in the distant future. The dilemma is obvious.

If the rough orbit is not released, there is little chance of further observations being obtained. If the orbit is released, it is inevitable that somebody will compute into the future and find that there is a small probability of an Earth collision.
The IAU Minor Planet Center is central to the process as it currently operates, and so it is not surprising that the press often state that "the IAU announces that an asteroid may hit the Earth in 20XX".

The scientific aspects of NEOs are actively pursued by Commissions 15 and 20.


NASA&rsquos Near-Earth Object Observations Program Discovers Ten Thousandth NEO

Asteroid 2013 MZ5 as seen by the University of Hawaii&rsquos PanSTARR-1 telescope. In this animated gif, the asteroid moves relative to a fixed background of stars. Asteroid 2013 MZ5 is in the right of the first image, towards the top, moving diagonally left/down. Image credit: PS-1/UH

Researchers have now discovered 10,000 near-Earth asteroids and comets, with the 10,000th being a 1,000 foot (300 meters) asteroid called 2013 MZ5.

More than 10,000 asteroids and comets that can pass near Earth have now been discovered. The 10,000th near-Earth object, asteroid 2013 MZ5, was first detected on the night of June 18, 2013, by the Pan-STARRS-1 telescope, located on the 10,000-foot (3,000-meter) summit of the Haleakala crater on Maui. Managed by the University of Hawaii, the PanSTARRS survey receives NASA funding.

Ninety-eight percent of all near-Earth objects discovered were first detected by NASA-supported surveys.

&ldquoFinding 10,000 near-Earth objects is a significant milestone,&rdquo said Lindley Johnson, program executive for NASA&rsquos Near-Earth Object Observations Program at NASA Headquarters, Washington. &ldquoBut there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth.&rdquo During Johnson&rsquos decade-long tenure, 76 percent of the NEO discoveries have been made.

Near-Earth objects (NEOs) are asteroids and comets that can approach the Earth&rsquos orbital distance to within about 28 million miles (45 million kilometers). They range in size from as small as a few feet to as large as 25 miles (41 kilometers) for the largest near-Earth asteroid, 1036 Ganymed.

Asteroid 2013 MZ5 is approximately 1,000 feet (300 meters) across. Its orbit is well understood and will not approach close enough to Earth to be considered potentially hazardous.

&ldquoThe first near-Earth object was discovered in 1898,&rdquo said Don Yeomans, long-time manager of NASA&rsquos Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. &ldquoOver the next hundred years, only about 500 had been found. But then, with the advent of NASA&rsquos NEO Observations program in 1998, we&rsquove been racking them up ever since. And with new, more capable systems coming on line, we are learning even more about where the NEOs are currently in our solar system, and where they will be in the future.&rdquo

Of the 10,000 discoveries, roughly 10 percent are larger than six tenths of a mile (one kilometer) in size &ndash roughly the size that could produce global consequences should one impact the Earth. However, the NASA NEOO program has found that none of these larger NEOs currently pose an impact threat and probably only a few dozen more of these large NEOs remain undiscovered.

The vast majority of NEOs are smaller than one kilometer, with the number of objects of a particular size increasing as their sizes decrease. For example, there are expected to be about 15,000 NEOs that are about one-and-half football fields in size (460 feet, or 140 meters), and more than a million that are about one-third a football field in size (100 feet, or 30 meters). A NEO hitting Earth would need to be about 100 feet (30 meters) or larger to cause significant devastation in populated areas. Almost 30 percent of the 460-foot-sized NEOs have been found, but less than 1 percent of the 100-foot-sized NEOs have been detected.

When it originated, the NASA-instituted Near-Earth Object Observations Program provided support to search programs run by the Massachusetts Institute of Technology&rsquos Lincoln Laboratory (LINEAR) the Jet Propulsion Laboratory (NEAT) the University of Arizona (Spacewatch, and later Catalina Sky Survey) and the Lowell Observatory (LONEOS). All these search teams report their observations to the Minor Planet Center, the central node where all observations from observatories worldwide are correlated with objects, and they are given unique designations and their orbits are calculated.

&ldquoWhen I began surveying for asteroids and comets in 1992, a near-Earth object discovery was a rare event,&rdquo said Tim Spahr, director of the Minor Planet Center. &ldquoThese days we average three NEO discoveries a day, and each month the Minor Planet Center receives hundreds of thousands of observations on asteroids, including those in the main-belt. The work done by the NASA surveys, and the other international professional and amateur astronomers, to discover and track NEOs is really remarkable.&rdquo

Within a dozen years, the program achieved its goal of discovering 90 percent of near-Earth objects larger than 3,300 feet (1 kilometer) in size. In December 2005, NASA was directed by Congress to extend the search to find and catalog 90 percent of the NEOs larger than 500 feet (140 meters) in size. When this goal is achieved, the risk of an unwarned future Earth impact will be reduced to a level of only one percent when compared to pre-survey risk levels. This reduces the risk to human populations, because once an NEO threat is known well in advance, the object could be deflected with current space technologies.

Currently, the major NEO discovery teams are the Catalina Sky Survey, the University of Hawaii&rsquos Pan-STARRS survey and the LINEAR survey. The current discovery rate of NEOs is about 1,000 per year.


Discovery of Near Earth Objects (NEO's) - Astronomy




10,000th near-Earth object discovered in space
JPL PRESS RELEASE
Posted: 29 June 2013

More than 10,000 asteroids and comets that can pass near Earth have now been discovered. The 10,000th near-Earth object, asteroid 2013 MZ5, was first detected on the night of June 18, 2013, by the Pan-STARRS-1 telescope, located on the 10,000-foot (3,000-meter) summit of the Haleakala crater on Maui. Managed by the University of Hawaii, the PanSTARRS survey receives NASA funding. False-colour image of cloud features seen on Venus by the Venus Monitoring Camera (VMC) on Venus Express. The image was captured from a distance of 30 000 km on 8 December 2011. The VMC was designed and built by a consortium of German institutes lead by the Max-Planck Institute for Solar System Research in Katlenburg-Lindau. Credit: ESA/MPS/DLR/IDA

Ninety-eight percent of all near-Earth objects discovered were first detected by NASA-supported surveys.

"Finding 10,000 near-Earth objects is a significant milestone," said Lindley Johnson, program executive for NASA's Near-Earth Object Observations Program at NASA Headquarters, Washington. "But there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth." During Johnson's decade-long tenure, 76 percent of the NEO discoveries have been made.

Near-Earth objects (NEOs) are asteroids and comets that can approach the Earth's orbital distance to within about 28 million miles (45 million kilometers). They range in size from as small as a few feet to as large as 25 miles (41 kilometers) for the largest near-Earth asteroid, 1036 Ganymed.

Asteroid 2013 MZ5 is approximately 1,000 feet (300 meters) across. Its orbit is well understood and will not approach close enough to Earth to be considered potentially hazardous.

"The first near-Earth object was discovered in 1898," said Don Yeomans, long-time manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "Over the next hundred years, only about 500 had been found. But then, with the advent of NASA's NEO Observations program in 1998, we've been racking them up ever since. And with new, more capable systems coming on line, we are learning even more about where the NEOs are currently in our solar system, and where they will be in the future."

Of the 10,000 discoveries, roughly 10 percent are larger than six-tenths of a mile (one kilometer) in size - roughly the size that could produce global consequences should one impact the Earth. However, the NASA NEOO program has found that none of these larger NEOs currently pose an impact threat and probably only a few dozen more of these large NEOs remain undiscovered.

The vast majority of NEOs are smaller than one kilometer, with the number of objects of a particular size increasing as their sizes decrease. For example, there are expected to be about 15,000 NEOs that are about one-and-half football fields in size (460 feet, or 140 meters), and more than a million that are about one-third a football field in size (100 feet, or 30 meters). A NEO hitting Earth would need to be about 100 feet (30 meters) or larger to cause significant devastation in populated areas. Almost 30 percent of the 460-foot-sized NEOs have been found, but less than 1 percent of the 100-foot-sized NEOs have been detected.

When it originated, the NASA-instituted Near-Earth Object Observations Program provided support to search programs run by the Massachusetts Institute of Technology's Lincoln Laboratory (LINEAR) the Jet Propulsion Laboratory (NEAT) the University of Arizona (Spacewatch, and later Catalina Sky Survey) and the Lowell Observatory (LONEOS). All these search teams report their observations to the Minor Planet Center, the central node where all observations from observatories worldwide are correlated with objects, and they are given unique designations and their orbits are calculated.

"When I began surveying for asteroids and comets in 1992, a near-Earth object discovery was a rare event," said Tim Spahr, director of the Minor Planet Center. "These days we average three NEO discoveries a day, and each month the Minor Planet Center receives hundreds of thousands of observations on asteroids, including those in the main-belt. The work done by the NASA surveys, and the other international professional and amateur astronomers, to discover and track NEOs is really remarkable."

Within a dozen years, the program achieved its goal of discovering 90 percent of near-Earth objects larger than 3,300 feet (1 kilometer) in size. In December 2005, NASA was directed by Congress to extend the search to find and catalog 90 percent of the NEOs larger than 500 feet (140 meters) in size. When this goal is achieved, the risk of an unwarned future Earth impact will be reduced to a level of only one percent when compared to pre-survey risk levels. This reduces the risk to human populations, because once an NEO threat is known well in advance, the object could be deflected with current space technologies.

Currently, the major NEO discovery teams are the Catalina Sky Survey, the University of Hawaii's Pan-STARRS survey and the LINEAR survey. The current discovery rate of NEOs is about 1,000 per year.


Scientists identify 29 planets where aliens could observe Earth

For centuries, Earthlings have gazed at the heavens and wondered about life among the stars. But as humans hunted for little green men, the extraterrestrials might have been watching us back.

In new research, astronomers have drawn up a shortlist of nearby star systems where any inquisitive inhabitants on orbiting planets would be well placed to spot life on Earth.

The scientists identified 1,715 star systems in our cosmic neighbourhood where alien observers could have discovered Earth in the past 5,000 years by watching it “transit” across the face of the sun.

Among those in the right position to observe an Earth transit, 46 star systems are close enough for their planets to intercept a clear signal of human existence – the radio and TV broadcasts which started about 100 years ago.

The researchers estimate that 29 potentially habitable planets are well positioned to witness an Earth transit, and eavesdrop on human radio and television transmissions, allowing any observers to infer perhaps a modicum of intelligence. Whether the broadcasts would compel an advanced civilisation to make contact is a moot point.

“One way we find planets is if they block out part of the light from their host star,” said Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell University in New York. “We asked, ‘Who would we be the aliens for if somebody else was looking?’ There is this tiny sliver in the sky where other star systems have a cosmic front seat to find Earth as a transiting planet.”

Earthly astronomers have detected thousands of planets beyond the solar system. About 70% are spotted when alien worlds pass in front of their host stars and block some of the light that reaches scientists’ telescopes. Future observatories, such as Nasa’s James Webb Space Telescope due to launch this year, will look for signs of life on “exoplanets” by analysing the composition of their atmospheres.

To work out which nearby star systems are well placed to observe an Earth transit, Kaltenegger and Dr Jackie Faherty, an astrophysicist at the American Museum of Natural History, turned to the European Space Agency’s Gaia catalogue of star positions and motions. From this they identified 2,034 star systems within 100 parsecs (326 light years) that could spot an Earth transit any time from 5,000 years ago to 5,000 years in the future.

One star known as Ross 128, a red dwarf in the Virgo constellation, is about 11 light years away – close enough to receive Earth broadcasts – and has a planet nearly twice the size of Earth. Any suitably equipped life on the planet could have spotted an Earth transit for more than 2,000 years, but lost the vantage point 900 years ago. If there is intelligent life on any of the two known planets orbiting Teegarden’s star, 12.5 light years away, it will be in a prime position to watch Earth transits in 29 years’ time.

At 45 light years away, another star called Trappist-1 is also close enough to eavesdrop on human broadcasts. The star hosts at least seven planets, four of them in the temperate, habitable zone, but they will not be in position to witness an Earth transit for another 1,642 years, the scientists write in Nature.

The findings come as the US government prepares to publish a hotly anticipated report on unidentified flying objects (UFOs). The report from the Pentagon’s Unidentified Aerial Phenomena Task Force, which was set up to gain insights into the nature and origins of unknown aircraft, is not expected to reveal evidence of alien antics, or rule it out.

Prof Beth Biller at Edinburgh University’s Institute for Astronomy, who was not involved in the Nature study, said the work could change how scientists approach Seti, the search for extraterrestrial life. “What was striking to me was how few of the stars within 100 parsecs could have viewed a transiting Earth,” she said.

“The transit method requires a very precise alignment between the transiting planet, its star, and the sun for a given planet to be detectable, so this result is not surprising. Now I am curious about what fraction of the stars in the Gaia catalogue of nearby stars have the right vantage point to detect the Earth via other exoplanet detection methods, such as the radial velocity method or direct imaging!”