near earth asteroid Archives

April 14, 2013June 5, 2022 by Ken Kremer

Orion Capsule Accelerating to 2014 Launch and Eventual Asteroid Exploration

A crane lifts the Orion EFT-1 crew module from its birdcage processing stand for transfer it to a dolly for continued assembly inside the Operations and Checkout Building high bay at NASA’s Kennedy Space Center in Florida as workers monitor progress. Orion’s first unpiloted test flight is scheduled to launch in 2014. Credit: NASA/Frankie Martin

NASA is picking up the construction pace on the inaugural space-bound Orion crew capsule at the Kennedy Space Center (KSC) in Florida – and accelerating towards blastoff on the unmanned Exploration Flight Test-1 mission (EFT-1) slated for September 2014 atop a mammoth Delta 4 Heavy Booster which will one day lead to deep space human forays to Asteroids and Mars.

Orion was at the center of an impressive and loud beehive of action packed assembly activities by technicians during my recent exclusive tour of the spacecraft to inspect ongoing progress inside the renovated Orion manufacturing assembly facility in the Operations and Checkout Building (O & C) at KSC.

“We plan to power up Orion for the first time this summer,” said Scott Wilson in an exclusive interview with Universe Today beside the Orion vehicle. Wilson is Orion’s Production Operations manager for NASA at KSC.

The Orion EFT-1 flight is a critical first step towards achieving NASA’s new goal of capturing and retrieving a Near Earth Asteroid for eventual visit by astronauts flying aboard an Orion vehicle by 2021 – if NASA’s budget request is approved.

An artist concept shows Orion as it will appear in space for the Exploration Flight Test-1 attached to a Delta IV second stage. Credit: NASA

KSC will have a leading role in NASA’s asteroid retrieval project that could occur some four years earlier than President Obama’s targeted goal of 2025 for a human journey to an asteroid.

Capturing an asteroid and dispatching astronauts aboard Orion to collect precious rock samples will aid our scientific understanding of the formation of the Solar System as well as bolster Planetary Defense strategies – the importance of which is gathering steam following the unforeseen Russian meteor strike in February which injured over 1200 people and damaged over 3000 buildings.

Dozens of highly skilled workers were busily cutting metal, drilling holes, bolting screws and attaching a wide range of mechanical and electrical components and bracketry to the Orion pressure vessel’s primary structure as Universe Today conducted a walk around of the EFT-1 capsule, Service Module and assorted assembly gear inside the O&C.

Orion EFT-1 crew cabin and full scale mural showing Orion Crew Module atop Service Module inside the O & C Building at the Kennedy Space Center, Florida. Credit: Ken Kremer/kenkremer.com

Lockheed Martin is the primary contractor for Orion. A growing number of employees hired by Lockheed and United Space Alliance (USA) are “working 2 shifts per day 7 days a week to complete the assembly work by year’s end,” said Jules Schneider, Orion Project manager for Lockheed Martin at KSC, during an exclusive interview with Universe Today.

I watched as the workers were boring hundreds of precision holes and carefully tightening the high strength steel bolts to attach the top to bottom ring segments made of titanium to the main load paths on the pressure vessel.

“We are installing lots of wiring to support ground test instrumentation for the strain gauges as well as microphones and accelerometers.”

“The simulated back shell panels are being installed now as guides,” said Wilson. “The real back shell panels and heat shield will be installed onto the structure later this year.”

“The heat shield is the biggest one ever built, 5 meters in diameter. Its bigger than Apollo and Mars Science Lab. It varies in thickness from about 1 to 3 inches depending on the expected heating.”

“We are making good progress on the Orion Service module too. The outer panels will be installed soon,” Wilson explained.

The olive green colored crew module was clamped inside the birdcage-like Structural Assembly Jig during my visit. The Jig has multiple degrees of freedom to maneuver the capsule and more easily enable the detailed assembly work.

“The technicians are installing strain gauges and secondary structure components to get it ready for the upcoming structural loads test,” said Schneider.

“After that we need to finish installing all the remaining parts of the primary structure and a significant portion of the secondary structure.”

For the next stage of processing, the EFT-1 crew module has been lifted out of the birdcage Jig and moved onto an adjacent dedicated work station for loads testing at the Operations and Checkout building.

As reported in my earlier article the Orion pressure vessel sustained three ‘hairline” cracks in the lower half of the aft bulkhead during proof pressure testing of the vessel and welds at the O & C.

I was observing as the technicians were carefully milling out the miniscule bulkhead fractures.

Workers have now installed custom built replacement brackets and reinforcing doublers on the aft bulkhead.

“We will do the protocol loads test with pressure using about 9 different load cases the vehicle will see during the EFT-1 flight. Chute deployment and jettison motor deployment is a driving load case,” said Schneider.

“We will also squeeze the capsule,” said Wilson.

“That structural loads testing of the integrated structure will take about 6 to 8 weeks. There are thousands of gauges on the vehicle to collect data,” Schneider elaborated.

“The test data will be compared to the analytical modeling to see where we are at and how well it matched the predictions – it’s like acceptance testing.”

“After we finish the structural loads tests we can than start the assembly and integration of all the other subsystems.”

“When we are done with the ground testing program then we remove all the ground test instrumentation and start installing all the actual flight systems including harnesses and instrumentation, the plumbing and everything else,” Schneider explained.

Orion hardware built by contractors and subcontractors from virtually every state all across the U.S is being delivered to KSC for installation onto EFT-1. Orion is a nationwide human spaceflight project.

Concept of Spacecraft with Asteroid Capture Mechanism Deployed. Credit: NASA.

During the unmanned Orion EFT-1 mission, the capsule will fly on a two orbit test flight to an altitude of 3,600 miles above Earth’s surface, farther than any human spacecraft has gone in 40 years.

It will then fire braking rockets to plunge back to Earth, re-enter the atmosphere at about 20,000 MPH and test numerous spacecrafts systems, the heat shield and all three parachutes for an ocean splashdown.

Meanwhile other Orion EFT-1 components such as the emergency Launch Abort System (LAS) and Service Module are coming together – read my Orion follow-up reports.

Humans have not ventured beyond low Earth orbit since the Apollo Moon landings ended in 1972. Orion will change that.

Ken Kremer

…………….

Learn more about Orion, Antares, SpaceX, Curiosity and NASA robotic and human spaceflight missions at Ken’s upcoming lecture presentations:

April 20/21 : “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus “The Space Shuttle Finale and the Future of NASA – Orion, SpaceX, Antares and more!” NEAF Astronomy Forum, Rockland Community College, Suffern, NY. 3-4 PM Sat & Sunday. Display table all day.

April 28: “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus the Space Shuttle, SpaceX, Antares, Orion and more. Washington Crossing State Park, Titusville, NJ, 130 PM

Orion EFT-1 crew cabin construction ongoing at the Kennedy Space Center which is due to blastoff in September 2014 atop a Delta 4 Heavy rocket. Credit: Ken Kremer

February 11, 2013December 23, 2015 by David Dickinson

Asteroid 2012 DA14: Observing Prospects and How to See It

Mark your calendars: this Friday, February 15, 2013, is the close flyby of Near Earth Asteroid 2012 DA14, passing just 27,630 kilometers (17,168 miles) from the surface of the Earth. About 50 meters (164 feet) in size, 2012 DA14 and its close shave marks the the first time there has been passage of an asteroid this close that we’ve known a year beforehand. Yes, it passes within the ring of geosynchronous satellites girdling the Earth. No, there’s no danger, either to said satellites or the Earth, so Bruce Willis can stay home for this one. But right behind those inquiries, the question we most frequently get is… how can I see it?

The orbital path of asteroid 2012 DA14 as seen face on (top) & near edge on (bottom). (Credit: JPL Small Body Database Browser).

The great news is that an advanced observer can indeed catch 2012 DA14 on its close pass the night of February 15^th… with a little skill and luck. Now for the bad news; the asteroid won’t be visible without binoculars or a telescope, and North America will largely miss out.

2012 DA14 will be really moving across the sky on closest approach, covering 0.8° per minute, or the diameter of a Full Moon every 45 seconds! With its passage closer to the Earth than the ring of geosynchronous satellites, it’s worth treating the passage of the asteroid as a satellite and hunting it down accordingly. Catching and watching such a pass can be an unforgettable experience; not many objects in the sky show such swift motion in real time. In fact, 2012 DA₁₄ will span the celestial sphere from declination -60° to +60° in just 4 hours! Needless to say, its passage through the Earth’s gravity well will alter its orbit considerably; most planetarium software programs do not account for this and thus will introduce a large error for a heliocentric object. Compounding the dilemma is the large amount of parallactic shift of such a nearby object. As viewed from the span of the Earth, 2012 DA14 will have a parallax of ~20° at greatest approach!

The path of asteroid 2012 DA14 through the celestial sphere on February 15th. (Created by Author).

But two sites on the web can help you with the search. One is Heavens-Above, which currently has a link on its main page to custom generate sky charts for specific locations for 2012 DA14 (make sure you’re logged in as a registered user and your observing location is set correctly). Another option is to generate an ephemeris customized for your location from the JPL Solar System Dynamics Horizons Web-Interface.

Asteroid 2012 DA14 is approaching the planet Earth from “down under,” and moving almost exactly parallel to the 12 hour line in right ascension. In fact, it’ll cross very near the equinoctial point in Virgo (one of the two points where the celestial equator and the ecliptic cross) shortly after its closest approach on Friday, February 15^th at 19:25UT. The asteroid will be at the local zenith (straight overhead) for observers in the pre-dawn hours located in western Indonesia at closest approach. Australia and eastern Asia will have a shot at seeing the asteroid as it whizzes through the sky in the early morning hours of February 16^th local. Observers in western Asia, Africa and Europe will see the asteroid lower to the east on the night of the 15^th. Note that 2012 DA14 juuuuuust misses Earth’s shadow (see strip chart) at closest approach. The shadow of our fair planet is ~20° across at the distance of the geosynchronous satellites; had it passed about a month later, we would have seen an “asteroid eclipse!” In fact, “eclipse season” for geosynchronous satellites occurs right around the equinoxes and is only a month away.

The “banana strip chart” shows the path of 2012 DA14 from the time it reaches a magnitude brighter than +10 at 17:40UT until it dips back down below it at 22:10UT on the same night. It also shows the width of uncertainty for its position due to the aforementioned 20° of parallax, and the points that it enters and departs the distance sphere of the geosynchronous satellites. Keep in mind, these satellites still orbit roughly hundred times higher than the International Space Station!

A good search strategy to catch 2012 DA14 is to actually to treat it like you’re hunting for a faint satellite. Find the time that it’s crossing a set declination and begin scanning with binoculars in right ascension back and forth until you “ambush” your astronomical prey moving slowly against the starry background. If using a telescope, use the lowest power and widest field of view that the instrument will allow. We’ve used this technique in the past to sweep up Near Earth Asteroids 2005 YU55 and 99942 Apophis and routinely use it to hunt for satellites fainter than naked eye visibility. At closest approach, asteroid 2012 DA14 will shine at around +8^th magnitude as it crosses the Bowl of Virgo northward past Denebola in the constellation Leo.

Recent measurements early this month conducted by astronomers at the Las Campanas observatory in Chile refined the orbit of 2012 DA14, placing its February 15^th passage just 45 kilometres closer to Earth than previously calculated but still well outside the threat zone. Campaigns are underway to refine measurements of its orbit even further on this pass. We won’t get another close pass of 2012 DA14 until February 16^th, 2046 when the asteroid misses us at about twice the distance of the Moon. An impact has been ruled out for this century. Predictions get less certain the further you project them into time, and 2012 DA14 will definitely be a space rock worth keeping tabs on!

March 1, 2012December 23, 2015 by Nancy Atkinson

Will Asteroid 2011 AG5 Hit Earth in 2040?

The orbit of asteroid 2011 AG5 carries it beyond the orbit of Mars and as close to the sun as halfway between Earth and Venus. Image credit: NASA/JPL/Caltech/NEOPO

[/caption]

You may have heard about an asteroid in the news this week that has a 1 in 625 chance of hitting Earth on Feb. 5, 2040. So, will this asteroid, named 2011 AG5, really hit our planet? The quick answer is, probably not. But astronomers will need more observations of this asteroid to say one way or the other for sure.

“Because of the extreme rarity of an impact by a near-Earth asteroid of this size, I fully expect we will be able to significantly reduce or rule out entirely any impact probability for the foreseeable future,” said Donald Yeomans, head of the Near-Earth Object Observations Program at NASA’s Jet Propulsion Laboratory.

Yeomans classified the chance of impact as “unlikely” and here are some facts that we do know about Asteroid about 2011 AG5:

What is the potential that this asteroid will impact Earth?

Currently astronomers have this asteroid ranked as a “1” on the 1 to 10 Torino Impact Hazard Scale. A “1” means this asteroid will have a pass near the Earth that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. Very likely, subsequent telescopic observations will lead to re-assignment to Level 0. The 1 in 625 chance is what the predictions are for the data that NASA has right now. Further observations will likely decrease the odds, and may even bring it to zero.

How big is this asteroid?

2011 AG5 is a 140-meter-wide (460 feet) space rock. Its composition is not yet known – whether it is a rocky, iron or icy asteroid.

How many Near Earth asteroids are out there?

Asteroid 2011 AG5 is one of 8,744 near-Earth objects that have been discovered so far, as of this week (March 1, 2012). NEOs are objects that come within 1.3 AU of the Sun (with Earth at 1 AU, so it means they pass through our neighborhood.)

1,305 of these NEOs have been classified as Potentially Hazardous Asteroids (PHAs), which are those that are larger than about 150 m (500 ft) and come within 0.05 AU of Earth’s orbit, so 2011 AG5 is right at the edge of that classification.

How was this asteroid discovered?

It was discovered on Jan. 8, 2011, by astronomers using a 60-inch Cassegrain reflector telescope located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona.

Where is 2011 AG5 now?

Its orbit carries it as far out as beyond Mars’ orbit and as close to the Sun as halfway between Earth and Venus. See the image above for its approximate current location. Its proximity to the Sun from our vantage point on Earth means astronomers can’t make observations right now.

When will astronomers find out more and be able to make better predictions?

“In September 2013, we have the opportunity to make additional observations of 2011 AG5 when it comes within 91 million miles (147 million kilometers) of Earth,” said Yeomans. “It will be an opportunity to observe this space rock and further refine its orbit.”

Yeomans added that even better observations will be possible in late 2015.

Will this asteroid come close to Earth before 2040?

2011 AG5 will next be near Earth in February of 2023 when it will pass the planet no closer than about 1.2 million miles (1.9 million kilometers). In 2028, the asteroid will again be in the area, coming no closer than about 12.8 million miles (20.6 million kilometers). The Near-Earth Object Program Office says the Earth’s gravitational influence on the space rock during these flybys has the potential to place the space rock on an impact course for Feb. 5, 2040, but this has very unlikely odds of occurring at 1-in-625.

“Again, it is important to note that with additional observations next year the odds will change and we expect them to change in Earth’s favor,” said Yeomans.

impact event — Screenshot from the Impact Earth website animation.

If Asteroid 2011 AG5 were to hit Earth, what is the potential for damage to Earth?

According to calculations from the Impact Earth website, an object of this size would begin to break up in Earth’s atmosphere at an altitude of 65500 meters (215,000 ft). Some of the larger pieces would reach the ground, with the pieces hitting Earth’s surface (ground) at a velocity Of 2.64 km/s (1.64 miles/s). The impact energy would be 7.52 x 10^15 Joules, or 1.8 MegaTons.

This would not cause any global problems, as the planet as a whole would not be strongly disturbed by the impact.

The broken projectile fragments would strike the ground in an ellipse about 1.17 km by 0.824 km in diameter, and the result of the impact is a crater field, not a single crater. The largest crater would be about 400 meters in diameter (1,310 feet). The impact would create a Richter Scale Magnitude-like event of 4.8.

If you were 1-10 km away from the impact area, you would feel a sensation like a heavy truck striking building. Standing cars would be rocked noticeably. Indoors, dishes and windows, might be disturbed and walls might make a cracking sound. An air blast at speeds of 26.3 m/s = 58.9 mph would arrive approximately 10 – 30 seconds after impact.

If this impactor hit in an ocean, the impact-generated tsunami wave would arrive approximately 6.18 minutes after impact if you were 10 km away, with a wave amplitude is between: 4.78 and 9.55 meters (15.7 feet and 31.3 feet).

How often do asteroids hit the Earth?

Yeomans said that every day, Earth is pummeled by more than 100 tons of material that spewed off asteroids and comets. Fortunately the vast majority of this “spillover” is just dust and very small particles. “We sometimes see these sand-sized particles brighten the sky, creating meteors, or shooting stars, as they burn up upon entry into Earth’s atmosphere,” Yeomans said in his “Top Ten Asteroid Factoids” article. “Roughly once a day, a basketball-sized object strikes Earth’s atmosphere and burns up. A few times each year, a fragment the size of a small car hits Earth’s atmosphere. These larger fragments cause impressive fireballs as they burn through the atmosphere. Very rarely, sizable fragments survive their fiery passage through Earth’s atmosphere and hit the surface, becoming meteorites.”

More info:
Catalina Sky Survey
Minor Planet Center
Asteroid and Comet Impact Hazards website from NASA
NASA’s Near Earth Object Program
Impact Earth website

October 14, 2010June 7, 2017 by Nancy Atkinson

Is the World Ready for An Asteroid Threat? Apollo’s Schweickart Pushes for Action

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

If we discover an asteroid heading directly towards Earth, are we ready to deal with the challenges of either deflection strategies or an evacuation prior to impact? Apollo 9 astronaut Rusty Schweickart has spent years championing the need for the human race to prepare for what will certainly happen one day: an asteroid threat to Earth. Schweickart is Chairman of the Board of the B612 Foundation, a non-profit private foundation that supports the development and testing of a spaceflight concept to protect the Earth from future asteroid impacts, and he says we have the technology today to deal with it, but nothing has been verified or tested. “We need to mobilize that technology and achieve an international consensus on what actions should be taken,” he told Universe Today.

Schweickart also co-chairs — with another former astronaut, Tom Jones — the Planetary Defense Task Force of the NASA Advisory Council. On October 6, 2010, the Task Force submitted a list of five recommendations to the Council to suggest how NASA should organize, investigate, prepare, and lead national and international efforts defending our planet from an asteroid impact.

“Our report and recommendations are a necessary, but not sufficient element of a sequence of actions which hopefully will lead to humanity being able to prevent future asteroid impacts with Earth,” Schweickart explained. “Assuming positive action by OSTP (Office of Science and Technology Policy) and the Congress, we’ll be well on our way to preventing future impact disasters.”

The report stresses that NASA should significantly improve the ability to discover and track potential NEO impactors to allow for early detection, develop effective impact mitigation techniques, and prepare an adequate response to the range of potential impact scenarios.

These recommendations have been approved by the Advisory Council, and the report was submitted to the NASA Administrator. Then, the Office of Science and Technology Policy (OSTP) is supposed to make a decision by tomorrow – Friday, October 15, 2010 –to make assignments in the US government as to what the breakdown of work should be to protect the Earth from an asteroid impact.

Among the recommendations in the PDTF report is developing mitigation techniques. But could NASA do this type of work within their new budget? “People intuitively think that if you’re going to be pushing asteroids around, that work will take over NASA,” said Schweickart said in a phone interview with Universe Today . “Wrong. It would be a ripple in NASA’s budget, a pimple, 1.5-2.0 percent at the most of NASA’s annual budget for 10 years then dropping back to less than 0.5%. It does not displace anything else that NASA is doing. It would be a small budgetary issue, but the importance of it is huge. This saves lives, protects the global environment, and saves future generations.”

*Update (10/16/10) Schweickart asked to add to his comments about budgetary needs, as there were some misinterpretations. “I certainly did not intend that it be interpreted as no budget increment is needed! In fact our report makes very clear that we strongly recommend that Congress increment the existing budget for this purpose and not take it out of existing programs. It is not costly, but other NASA programs should not be penalized in order to support a responsible, public safety program which would amount to only a 1.5-2.0% increment in the NASA budget.”

Artist concept of a space tug. Credit: NASA

The technology needed exists today, Schweickart said, “that is, we do not have to go into a big technology development program in order to deflect most asteroids that would pose a threat of impact. However, that technology has not been put together in a system design, and not been verified, tested or demonstrated that it could actually deflect an asteroid. So, we need to test everything – test the very sequence we would use for a deflection campaign.”

The best way to test it would be to have NASA, or perhaps a consortium of space agencies, carry out an actual mission to test the entire system.

“Not with an asteroid that threatens an impact,” said Schweickart, “but with an asteroid that is just minding its own business, and we’d have the opportunity to show we can change its orbit slightly in a controlled way.”

The crew of Apollo 9: Commander James McDivitt, Command Module Pilot Dave Scott and Lunar Module Pilot Rusty Schweickart. Credit: NASA

Schweickart said the B612 foundation, and the Association of Space Explorers (ASE; the professional organization of astronauts and cosmonauts from around the world) and every planetary defense conference held recently has discussed the need for such a capability validation.

But the recommendations made by the PDTF are, for now just suggestions, and certainly not a mandate for NASA to prepare in a meaningful way for an asteroid threat.

“There’s no official design of a deflection mission because there is no responsibility to do it,” Schweickart said. “Right now, NASA’s assignment is only to find these asteroids. Period. That’s it.”

But, with the October 15 deadline almost here, Schweickart is hopeful. “Hopefully, that will begin the process of NASA actually having this responsibility,” he said, “and that Congress will respect that and a budget be allocated in order to do the job. Then mission planners can start designing demonstration missions.”

However, if the past is any indication, any mandate wouldn’t necessarily mean a mission would happen soon.

The Pan-STARRS telescope on Haleakala, Hawaii. Photograph by Rob Ratkowski for the PS1SC

Congress directed NASA to do the “Spaceguard” survey to find all asteroids around 40 meters and larger by 2020. “To come close to achieving that, we need to have new telescopes that will have greater capabilities than what we’ve been using to date,” said Schweickart. “Right now the Pan-STARRS telescope has the equivalent of one eye squinting, and it is not exactly knocking everybody’s socks off. LSST (Large Synoptic Survey Telescope) is still hundreds of millions of dollars before being a fully funded project.”

Schweickart said the Task Force heard presentations on perhaps better ways to complete that Congressional goal and their report indicates that at least 87% of the large asteroids whose impacts could pose a global threat to our civilization have been discovered. Right now, none pose a credible threat of a collision with Earth for the foreseeable future. But the discovery rate of the much more numerous smaller NEOs, — which represent a regional or local impact hazard — “will soon confront us with objects presenting worrisome but uncertain probabilities for a future collision with Earth. Such situations will appear more frequently as the discovery rate increases, and the nation presently has no clear policy on how to address such a situation,” the report says.

“Congress’s favorite thing to do is to tell you to do something and not give you any money for it,” Schweickart said. “That is not very responsible and it doesn’t always work and it’s not the right way a government should operate, especially where public safety is at issue. Therefore it is important that the OSTP lead the way on this issue on October 15.”

Tomorrow: What would an asteroid deflection campaign entail?

For more information:
B612 Foundation

Planetary Defense Task Force of the NASA Advisory Council

Office of Science and Technology Policy

Pan-STARRS

Large Synoptic Survey Telescope

January 25, 2010December 24, 2015 by Nancy Atkinson

WISE Bags its First Near-Earth Asteroid

The red dot at the center of this image is the first near-Earth asteroid discovered by NASA's Wide-Field Infrared Survey Explorer, or WISE Image credit: NASA/JPL-Caltech/UCLA

[/caption]

Well, that didn’t take long: The WISE spacecraft (Wide-field Infrared Survey Explorer) spotted its first near-Earth asteroid on January 12, 2010, two days before the official start of its all-sky survey. That’s a pretty good catch, considering WISE just popped it lens cover a couple of weeks ago (December 29, 2009) and released its “first light” image on January 6. This is the first of what researchers hope will be thousands of previously undiscovered asteroids in the main asteroid belt, and hundreds of new near-Earth asteroids. By mapping the whole sky in infrared light, it should also be able to capture millions of new stars and galaxies.

WISE’s software picked up the object, 2010 AB78, moving against a background of stationary stars. Researchers followed up and confirmed the discovery with the University of Hawaii’s 2.2-meter (88-inch) visible-light telescope near the summit of Mauna Kea.

This asteroid does not pose any foreseeable impact threat to Earth, but scientists will continue to monitor it. 2010 AB78 is currently about 158 million kilometers (98 million miles) from Earth. It is estimated to be roughly 1 kilometer (0.6 miles) in diameter and circles the sun in an elliptical orbit tilted to the plane of our solar system. The object comes as close to the sun as Earth, but because of its tilted orbit, it is not thought to pass near our planet.

Source: JPL