Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

European Space Agency to probe asteroid blind spot

15.04.2002


Artist’s impression on an asteroid impact with the Earth
® ESA


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.

Monica Talevi | alphagalileo
Further information:
http://www.esa.int/export/esaCP/ESA93VF18ZC_index_0.html

More articles from Physics and Astronomy:

nachricht Water without windows: Capturing water vapor inside an electron microscope
13.12.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

nachricht Columbia engineers create artificial graphene in a nanofabricated semiconductor structure
13.12.2017 | Columbia University School of Engineering and Applied Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>