. 24/7 Space News .
Ulysses Catches Another Comet

Artist's impression of Ulysses crossing the tail of Comet Hyakutake in 1996. Illustration by David A. Hardy. Copyright ESA.
Paris (ESA) Feb 13, 2004
Ulysses is not normally associated with the study of comets. Nonetheless, the European-built space probe demonstrated its ability as a "comet catcher" when it crossed the distant tail of comet Hyakutake (C/1996 B2) in 1996.

In an article soon to appear in Astrophysical Journal Letters, the same Ulysses teams that identified that particular comet tail present evidence for one (and possibly two) new tail crossings. This time, however, Ulysses needed a little help from the Sun to make the right connection.

The comets involved were McNaught-Hartley (C/1991 T1) and SOHO (C/2000 S5). Unlike Hyakutake, these comets seemed to be at the wrong location for Ulysses to intercept their tails. By chance, a Coronal Mass Ejection moving away from the Sun enveloped both the comet and the spacecraft, carrying the cometary material to Ulysses.

Comets such as McNaught-Hartley are often likened to "dirty snowballs". They come from the deep freeze of the outer solar system, travelling on orbits that carry them close to the Sun. As they approach the inner solar system, the comets warm up, releasing gas and dust that forms a cloud around the cometary nucleus. Under the influence of sunlight and the solar wind, the gas atoms become electrically charged, and form what is known as the comet's ion tail.

"The solar wind causes the ion tail to point away from the Sun, acting just like an interplanetary windshock", said Richard Marsden, ESA's Mission Manager for Ulysses. In fact, back in the 1950s, a scientist called Ludwig Biermann inferred the existence of the solar wind from observations of comet tails.

Violent eruptions on the Sun can throw huge clouds of ionised gas into space. Known as Coronal Mass Ejections (or CMEs), these clouds travel away from the Sun at speeds of up to 2000 kms-1, and are responsible for many of the effects of space weather.

As they plough through the solar wind, CMEs often produce a significant distortion of the interplanetary magnetic field that is carried away from the Sun by the solar wind. It was just such a distortion that is believed to have connected the comets McNaught-Hartley and C/2000 S5 to Ulysses.

"The ability of CMEs to carry cometary ions far from their radial paths significantly increases the chance of detecting these ions", said Prof. George Gloeckler, Principal Investigator of the Solar Wind Ion Composition Spectrometer (SWICS) experiment on Ulysses that made the discovery. Serendipitous encounters with comet tails cannot replace dedicated missions like ESA's Rosetta. Even so, they are helping scientists to unravel the mysteries of these icy visitors to the inner solar system.

Related Links
Ulysses at ESA
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

UK Scientists All Set For New Year Encounter With A Comet
London - Dec 17, 2003
On January 2nd 2004 the NASA space mission, Stardust, will fly through comet Wild 2, capturing interstellar particles and dust and returning them to Earth in 2006. Space scientists from the Open University and University of Kent have developed one of the instruments which will help tell us more about comets and the evolution of our own solar system and, critical for Stardust, its survival in the close fly-by of the comet.



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














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.