Recent research shows that the space age has coincided with a period of unusually high solar activity, called a grand maximum. Isotopes in ice sheets and tree rings tell us that this grand solar maximum is one of 24 during the last 9300 years and suggest the high levels of solar magnetic field seen over the space age will reduce in future. This decline will cause a reduction in sunspot numbers and explosive solar events, but those events that do take place could be more damaging. Graduate student Luke Barnard of the University of Reading will present new results on 'solar climate change' in his paper at the National Astronomy Meeting in Manchester.
The level of radiation in the space environment is of great interest to scientists and engineers as it poses various threats to man-made systems including damage to electronics on satellites. It can also be a health hazard to astronauts and to a lesser extent the crew of high-altitude aircraft.
The main sources of radiation are galactic cosmic rays (GCRs), which are a continuous flow of highly energetic particles from outside our solar system and solar energetic particles (SEPs), which are accelerated to high energies in short bursts by explosive events on the sun. The amount of radiation in the near-Earth environment from these two sources is partly controlled in a complicated way by the strength of the Sun's magnetic field.
There are theoretical predictions supported by observational evidence that a decline in the average strength of the Sun's magnetic field would lead to an increase in the amount of GCRs reaching near-Earth space. Furthermore there are predictions that, although a decline in solar activity would mean less frequent bursts of SEPs, the bursts that do occur would be larger and more harmful.
Currently spacecraft and aircraft are only designed and operated to offer suitable protection from the levels of radiation that have been observed over the course of the space age. A decline in solar activity would result in increased amounts of radiation in near-Earth space and therefore increased risk of harm to spacecraft and aircraft and the astronauts and aircraft crews that operate them.
By comparing this grand maximum with 24 previous examples, Mr Barnard predicts that there is an 8% chance that solar activity will fall to the very low levels seen in the so-called 'Maunder minimum', a period during the seventeenth century when very few sunspots were seen. In this instance, the flux of GCRs would probably increase by a factor of 2.5 from present day values and the probability of observing a large SEP event will fall from the presently seen 5 down to 2 events per century.
However, the more probable scenario is that solar activity will decline to approximately half its current value in the next 40 years, in which case the flux of GCRs will increase by a factor of 1.5 and the probability of large SEP events to increase from the current value to 8 events per century. As a result the near-Earth space radiation environment will probably become more hazardous in the next 40 years.
In presenting his results, Mr Barnard comments: "Radiation in space can be a serious issue for both people and the delicate electronic systems that society depends on. Our research shows that this problem is likely to get worse over the coming decades – and that engineers will need to work even harder to mitigate its impact."
IMAGE, VIDEOS AND CAPTION
Images and videos of a Coronal Mass Ejection (CME) can be downloaded from http://sdo.gsfc.nasa.gov/gallery/main.php?v=item&;id=80
A high-resolution version of the same image is available at http://sdo.gsfc.nasa.gov/gallery/gallery/assets/print/M2_CME.tif
Caption: Image of a coronal mass ejection (CME) on June 7, 2011, recorded in ultraviolet light by the Solar Dynamics Observatory (SDO) satellite. The shock front that forms ahead of these huge expulsions of material from the solar atmosphere (the event shown moved at 1400 km/s) can generate large fluxes of highly energetic particles at Earth which can be a considerable hazard to space-based electronic systems and with repeated exposure, a health risk for crew on board high-altitude aircraft. Credit: NASA / SDO
NAM 2012 Press Office (0900 – 1730 GMT, 27-29 April; 0900 – 1630 GMT 30 April)
University Place building
University of Manchester
Tel: +44 (0)161 306 7313
Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
Royal Astronomical Society
Mob: +44 (0)7756 034 243
Dr Klaus Jaeger
Department of Meteorology
University of Reading
Tel: +44 (0)118 378 8950
Mob: +44(0) 759 062 2956
NOTES FOR EDITORS
Bringing together more than 900 astronomers and space scientists, the National Astronomy Meeting (NAM 2012) will take place from 27-30 March 2012 in the University Place conference centre at the University of Manchester in the UK. The conference is a joint meeting of the Royal Astronomical Society (RAS) and the German Astronomische Gesellschaft (AG) and is held in conjunction with the UK Solar Physics (UKSP: www.uksolphys.org) and Magnetosphere Ionosphere Solar Terrestrial (MIST: www.mist.ac.uk) meetings. NAM 2012 is principally sponsored by the RAS, AG, STFC and the University of Manchester.
The Royal Astronomical Society
The Royal Astronomical Society (RAS: www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The Astronomische Gesellschaft (AG)
The Astronomische Gesellschaft (AG: www.astronomische-gesellschaft.de), founded in 1863, is a modern astronomical society with more than 800 members dedicated to the advancement of astronomy and astrophysics and the networking between astronomers. It represents German astronomers, organises scientific meetings, publishes journals, offers grants, recognises outstanding work through awards and places a high priority on the support of talented young scientists, public outreach and astronomy education in schools.
The Science and Technology Facilities Council
The Science and Technology Facilities Council (STFC: www.stfc.ac.uk) is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. It enables UK researchers to access leading international science facilities for example in the area of astronomy, the European Southern Observatory.
Jodrell Bank Centre for Astrophysics
The Jodrell Bank Centre for Astrophysics (JBCA: www.jb.man.ac.uk/) is part of the School of Physics & Astronomy at the University of Manchester. JBCA is split over two main sites: the Alan Turing Building in Manchester and the Jodrell Bank Observatory in Cheshire. At Jodrell Bank Observatory, the new Jodrell Bank Discovery Centre is a key focus for our work in public engagement and education. Jodrell Bank is a world leader in radio astronomy-related research and technology development with a research programme extending across much of modern astrophysics. The group operates the e-MERLIN national radio astronomy facility and the iconic Lovell Telescope, hosts the UK ALMA Regional Centre Node and is home to the international office of the SKA Organisation. Funded by the University, the Science & Technology Facilities Council and the European Commission, it is one of the UK's largest astrophysics research groups.
domingo, 1 de abril de 2012
RV: Solar ‘climate change’ could cause rougher space weather
Publicado por Justi en 5:15