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 A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

nachricht Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Explaining how 2-D materials break at the atomic level

18.01.2017 | Materials Sciences

Data analysis optimizes cyber-physical systems in telecommunications and building automation

18.01.2017 | Information Technology

Reducing household waste with less energy

18.01.2017 | Ecology, The Environment and Conservation

VideoLinks
B2B-VideoLinks
More VideoLinks >>>