Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study indicates space weather may be to blame for some satellite failures

17.09.2013
MIT study finds that high-energy electrons in space may be to blame for some satellite failures

Is your cable television on the fritz? One explanation, scientists suspect, may be the weather — the weather in space, that is.

MIT researchers are investigating the effects of space weather — such as solar flares, geomagnetic storms and other forms of electromagnetic radiation — on geostationary satellites, which provide much of the world's access to cable television, Internet services and global communications.

Geostationary satellites orbit at the same rate as the Earth's rotation, essentially remaining above the same location throughout their lifetimes. These satellites are designed to last up to 15 years, during which time they may be bombarded by charged particles. Most satellites cover sensitive electronics with layers of protective shielding, but over time, radiation can penetrate and degrade a satellite's components and performance.

"If we can understand how the environment affects these satellites, and we can design to improve the satellites to be more tolerant, then it would be very beneficial not just in cost, but also in efficiency," says Whitney Lohmeyer, a graduate student in MIT's Department of Aeronautics and Astronautics.

Lohmeyer is working with Kerri Cahoy, an assistant professor of aeronautics and astronautics, to understand how sensitive components are to the weather conditions in space, and how space weather may contribute to failures.

In a paper published in the journal Space Weather, the team analyzed space weather conditions at the time of 26 failures in eight geostationary satellites over 16 years of operation. The researchers found that most of the failures occurred at times of high-energy electron activity during declining phases of the solar cycle. This particle flux, the scientists theorize, may have accumulated in the satellites over time, creating internal charging that damaged their amplifiers — key components responsible for strengthening and relaying a signal back to Earth.

Lohmeyer says a better understanding of space weather's effects on satellites is needed not just for current fleets, but also for the next generation of communications satellites.

"Users are starting to demand more capabilities," Lohmeyer notes. "They want to start video-streaming data, they want to communicate faster with higher data rates. So design is changing — along with susceptibilities to space weather and radiation that didn't used to exist, but are now becoming a problem."

Space-weather disconnect

Today, engineers design satellites with space weather in mind, using radiation models to predict how much radiation a satellite may be exposed to over its lifetime. Cahoy notes that a satellite's radiation exposure may vary depending on its orbit. For instance, some orbits are more dangerous than others; engineers choose components that can survive and operate in such environments.

"But space weather is a lot more dynamic than models predict, and there are many different ways that charged particles can wreak havoc on your satellite's electronics," Cahoy adds. "The hard part about satellites is that when something goes wrong, you don't get it back to do analysis and figure out what happened."

To add another layer of complication, Lohmeyer points out a "disconnect" between satellite engineers and space-weather forecasters.

"The space-weather community provides forecasting mechanisms for companies to help them better operate their satellites, and they may say, 'Space-weather activity is incredibly high right now, we're putting out a warning,'" Lohmeyer says. "But engineers and operators don't really understand what this implies."

Lohmeyer's primary goal, she says, is to bridge the gap between the space-weather community and satellite engineers.

Reading the space forecast

To establish a better understanding of space weather's effects on satellite equipment, Cahoy and Lohmeyer partnered with Inmarsat, a telecommunications company based in London. The researchers analyzed more than 665,000 operational hours of telemetry data from eight of the company's satellites, including temperature and electric-current measurements from the satellites' solid-state amplifiers. From these data, the researchers analyzed scientific space-weather data coinciding with 26 anomalies from 1996 to 2012, the majority of which were considered "hard failures" — unrecoverable failures that may lead to a temporary shutdown of the spacecraft.

The team noted the dates and times of each failure, and then analyzed the weather conditions leading up to each failure, using observations from multiple space-weather satellites. Such observations included solar-flare activity and geomagnetic storms.

Specifically, the researchers analyzed the Kp index, a measurement of geomagnetic activity that is represented along a scale from zero to nine. Satellite engineers incorporate the Kp index into radiation models to anticipate space conditions for a particular spacecraft's orbit. However, as the team found, most of the amplifier failures occurred during times of low geomagnetic activity, with a Kp index of three or less — a measurement that engineers would normally consider safe. The finding suggests that the Kp index may not be the most reliable metric for radiation exposure.

Instead, Cahoy and Lohmeyer discovered that many amplifiers broke down during times of high-energy electron activity, a phenomenon that occurs during the solar cycle, in which the sun's activity fluctuates over an 11-year period. The flux of high-energy electrons is highest during the declining phase of the solar cycle — a period during which most amplifier failures occurred.

Lohmeyer says that over time, such high-energy electron activity may penetrate and accumulate inside a satellite, causing internal charging that damages amplifiers and other electronics. While most satellites carry back-up amplifiers, she notes that over an extended mission, these amplifiers may also fail.

"Once you get into a 15-year mission, you may run out of redundant amplifiers," Lohmeyer says. "If a company has invested over $200 million in a satellite, they need to be able to assure that it works for that period of time. We really need to improve our method of quantifying and understanding the space environment, so we can better improve design."

Written by Jennifer Chu, MIT News Office

Andrew Carleen | EurekAlert!
Further information:
http://www.mit.edu

More articles from Studies and Analyses:

nachricht Real-time feedback helps save energy and water
08.02.2017 | Otto-Friedrich-Universität Bamberg

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>