Antenna Anomaly May Affect SOHO Scientific Data Transmission

SOLAR SCIENCE

SOHO has been an outstanding success and will surely be replaced with another "solar weathr station"

Paris - Jun 25, 2003
The Solar and Heliospheric Observatory (SOHO) spacecraft expects to experience a blackout in the transmission of its scientific data during the week of 22 June 2003. This is estimated to last for about two and a half to three weeks.

Engineers are predicting this problem after detecting a malfunction in the pointing mechanism of the satellite's high-gain antenna (HGA), which is used to transmit the large amounts of data from SOHO's scientific observations to Earth.

The SOHO spacecraft is operating as safely as before the problem occurred. Its low gain antenna, which does not need to be pointed in a specific direction (omni-directional), will be used to control the spacecraft and monitor both spacecraft and instrument health and safety.

The anomaly in pointing the high-gain antenna was recently discovered when engineers detected a discrepancy between the commanded and measured antenna position. In normal conditions, the antenna must be able to move along two axes, vertical and horizontal. The horizontal movement was no longer taking place properly. The problem is probably due to a malfunction in the motor or gear assembly that steers the antenna.

SOHO is located 1.5 million kilometers (one million miles) from Earth, slowly orbiting around the First Lagrangian point, where the combined gravity of the Earth and the Sun keep SOHO in an orbit locked to the Sun-Earth line. To transmit data, the SOHO high-gain antenna must rotate to have the Earth constantly in its field of view as the spacecraft and the Earth progress in their respective orbits.

If the problem is not solved, the Earth will be left outside the HGA beam on a periodic basis, with similar blackouts occurring every three months.

ESA and NASA engineers are currently assessing several options to recover the situation, or minimize the scientific data loss.

SOHO is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. It was launched in December 1995 on an Atlas IIAS/Centaur rocket.

SOHO moves around the Sun in step with the Earth, by slowly orbiting around the First Lagrangian Point (L1), where the combined gravity of the Earth and Sun keep SOHO in an orbit locked to the Earth-Sun line.

The L1 point is approximately 1.5 million kilometres away from Earth (about four times the distance of the Moon), in the direction of the Sun. There, SOHO enjoys an uninterrupted view of our daylight star.

Besides watching the sun, SOHO has become the most prolific discoverer of comets in astronomical history: as at May 2003, more than 620 comets had been found by SOHO and now carry its name. SOHO's easily accessible, spectacular data and basic science results have captured the imagination of the space science community and the general public alike.

SOLARSCIENCE

Vast Conveyer Belts Drive 11-Year Cycle Of Solar Maximum

Huntsville - Jun 23, 2003
NASA and university astronomers have found evidence that the 11-year sunspot cycle is driven in part by a giant conveyor belt-like, circulating current within the Sun.

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.