Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



ESA To Probe Asteroid Blind Spot

Gaia will probe the asteroid blind spot ESA's Gaia spacecraft will be ideally situated to probe the asteroid blind spot between the Sun and Earth. This artist's impression indicates how regions of the sky that are unobservable from Earth can be observed by Gaia. (Not to scale).
  • full size chart at ESA
  • Paris (ESA) Apr 18, 2002
    In the past five weeks two asteroids have passed close by Earth, at distances of 1.2 and 3 times the distance to the Moon. Another asteroid has recently been shown to be on course for a collision with Earth in 2880.

    Monitoring known asteroids allows astronomers to predict which may collide with Earth. But that is only true for the asteroids we know of. What about those that lie in the asteroid blind spot between the Sun and Earth? The European Space Agency is studying ways in which its missions can assist in monitoring these unseen but potentially hazardous asteroids.

    It is difficult to estimate the danger posed by asteroids. This is, in part, because astronomers do not yet know how many asteroids there are. A recent discovery, made using data from ESA's Infrared Space Observatory (ISO), showed that there could be nearly two million asteroids larger than one kilometre in the main asteroid belt, between Mars and Jupiter. That is more than twice as many as previously thought.

    In addition, even when an asteroid is identified many observations must be made before it is known whether or not it will come close to, or even collide with, Earth.

    If the asteroids remained in the main-belt, they would pose no danger to Earth. However, they can be thrown into different orbits by collisions with other asteroids or by the influence of Jupiter's gravitational field. If their new orbits cross the Earth's orbit, they could one day collide with our planet, inflicting unprecedented devastation.

    A number of ground-based searches are already underway to find as many potentially hazardous asteroids (PHAs) as possible but there is a notorious 'blind spot' that telescopes on Earth can never peer into.

    It is the region of space inside Earth's orbit, towards the Sun. From Earth, astronomical observations close to the Sun are almost impossible because it means observing during the daytime when only the brightest celestial objects stand out from the blue sky.

    That means asteroids lurking in this region of space can 'sneak up' on the Earth undetected. Asteroid 2002 EM7, which passed close by the Earth on 8 March this year, was one such object and was only detected after it crossed Earth's orbit to appear briefly in the night sky, before it crossed back into the glare of the Sun.

    About 550 similar asteroids are known. They are called the Atens and spend most of their time inside Earth's orbit, close to the Sun. Traditional estimates suggest there may be several thousand in total and tracking them from Earth is next to impossible. However, a study performed for ESA has shown that the Gaia spacecraft will be able to see clearly into this 'blind spot' and keep precise track of the Aten population.

    François Mignard of Observatoire de la Côtes d'Azur, France, conducted the study. He found that Gaia would be ideal because it is designed to measure the position of celestial objects with unprecedented accuracy. In addition, since there is no atmosphere in space to scatter the Sun's rays and create a blinding blue sky, Gaia can see close to the Sun without disturbance.

    Gaia is expected to be launched around 2010. Even if ground-based searches have spotted more Atens by that time, the mission still has an essential role to play because it will reveal their orbits to a precision 30 times better than any observation from the ground, thus identifying whether any pose a danger to Earth.

    "To know how close these objects will come to Earth is very dependent on how accurately one can measure their orbits. That's the main contribution that Gaia can be expected to make," says Michael Perryman, project scientist for Gaia, at ESA's European Space Research and Technology Centre in the Netherlands.

    Gaia's data will also provide astronomers with a first estimate of these objects' composition. This knowledge could help to determine methods to divert or destroy asteroids that are set on a collision course with Earth.

    Several ESA missions are contributing, or will contribute, to our understanding of minor bodies of the Solar System: these include ISO, Gaia and Rosetta, which will study asteroids Siwa and Otawara. ESA is also considering the addition of an asteroid spotting telescope to its BepiColombo mission.

    Related Links
    More about Gaia
    SpaceDaily
    Search SpaceDaily
    Subscribe To SpaceDaily Express

    Smaller Asteroids Can Be Deflected From Earth With A Paint Job
    Tucson - Apr 05, 2002
    Humans could deflect small but dangerous asteroids from Earth by changing how much sunlight the asteroids reflect, a University of Arizona planetary scientist suggests in the current issue (April 5) of Science.

    There's A Rock Headed Our Way
    Pasadena - Apr 5, 2002
    We all know the story of David and Goliath. Little David picks a stone, whirls it around and fells the giant Goliath. Nature, however, decided that our big, huge Goliath of a solar system would whirl a stone and send it hurtling toward the tiny David of our planet Earth. Don't start heading for the hills just yet, though. The dramatic event is 878 years away and there's a strong chance that the rock will whiz by and never touch us.



    Thanks for being here;
    We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

    With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

    Our news coverage takes time and effort to publish 365 days a year.

    If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

    SpaceDaily Contributor
    $5 Billed Once


    credit card or paypal
    SpaceDaily Monthly Supporter
    $5 Billed Monthly


    paypal only






    Memory Foam Mattress Review
    Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
    XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








    The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.