Press Release

Predicting the weather in space

By SpaceRef Editor
September 10, 2001
Filed under , ,

At the British Association for the Advancement of Science meeting in Glasgow
today, Dr Andrew Coates will unveil some of the new results from a year-long
study for the satellite insurance industry, via the Tsunami initiative,
on the effects of space weather on spacecraft. In particular a web-based
prediction system has been developed to warn of potential danger for
satellites, using a ‘red/amber/green’ traffic light system. This uses real
measured conditions from spacecraft upstream of Earth’s magnetic shield, to
predict the amount of dangerous ‘killer electrons’ nearer to Earth over the
following days. The team have found that conditions in the solar wind give
the best hope for prediction of these potentially damaging particles. They
are also developing a ‘black box’ detector for use on commercial spacecraft.

Space weather produces real problems for humankind and for space and ground-
based technology although we are shielded from the charged particle onslaught
by Earth’s magnetic field. As well as heat and light, the Sun produces a
million tonnes per second of solar wind on average. But the average picture
does not always hold. Events called coronal mass ejections fling 10 million
megatons of solar material into space, and some of these are directed at
Earth. When they reach Earth, charged particles from these events penetrate
Earth’s magnetic shield and cause problems for power distribution systems,
astronauts and satellites. In addition, solar flares can send particles
towards us at speeds close to the velocity of light. These in turn
can cause problems for satellites on which we increasingly rely for
communications, weather forecasting and positioning. The ‘killer electrons’
in the Earth’s environment are produced when particles entering from the
solar wind are accelerated to relativistic energies becoming part of the
radiation belts. The new predictions used by the web-based system are of
when this process occurs. Other work in MSSL’s space plasma group, which
Dr Coates leads, examines why the acceleration happens

Dr Coates’ talk (‘What is space weather and why is it important’, to be given
on 7 September at 1000 in Glasgow) is an introduction to space weather and
its effects, part of a session at the BA meeting on space weather. New
results from the Cluster spacecraft, which studies the science behind space
weather, and illustrations of the causes and effects of space weather, will
also be shown.

*****

BA presentation
[http://www.mssl.ucl.ac.uk/pages/news/spaceweather07Sept01/ba2001.htm]

As well as heat and light, the Sun emits a million tonnes of hot ‘solar wind’
per second on average. But the average picture does not always hold. During
brief ‘solar flares’ the Sun emits bursts of X- and gamma- rays, and
sometimes protons and electrons moving near the speed of light which can
reach Earth in less than an hour. Huge amounts, tens of billions of tonnes,
of charged solar material from events called ‘coronal mass ejections’ can
disrupt the solar wind and buffet Earth’s magnetic shield days later.
Energetic cosmic rays from beyond our solar system can punch though the
shield too, reaching the Earth’s atmosphere. And while we recently passed
the solar maximum, we are not even safe at the minimum of the 11-year solar
activity cycle.

All of these ‘space weather’ effects can have important implications for
humankind. In space, they can cause problems for satellites and astronauts,
on the ground, power systems can be affected, and in the atmosphere between,
there are effects on aircraft and on climate. There is much current interest
in understanding these problems and in predicting when they are likely to
happen.

The key to predicting space weather events is an understanding of the science
behind space weather. At the moment space weather prediction is at the same
state as terrestrial weather prediction was 50 years ago. To improve this we
need to understand how and why continuous and impulsive emissions from the
Sun occur. We need to understand how they propagate between Sun and Earth,
and how our magnetic shield is penetrated. We need to understand the effects
of solar wind changes on the Earth’s magnetosphere and radiation belts,
where satellites used in our daily lives are stationed and where ‘killer’
relativistic electrons are found. And we need to understand the coupling all
the way through from the Sun to our atmosphere.

Now, several international (European, American, Japanese and Russian)
scientific space missions are studying the chain of events from Sun to Earth.
Staring at the Sun like SOHO and TRACE, measuring the upstream solar wind
like ACE and Wind and inside our magnetosphere like Cluster, Polar and
Geotail, the results are helping us understand the coupling processes. For
example, the average electrical power incident on the Earth’s magnetic
shield is about 3 million megawatts, equivalent to mankind’s current energy
consumption, corresponding to only 40kg of solar wind material per second.
Only a few percent of this energy leaks in via ‘magnetic reconnection’ —
an explosive small-scale plasma process which results in magnetic field
being pulled over Earth’s magnetic shield like peeling a banana and
particles entering along punctures in our shield.

A search for understanding is vital. But we can also use the knowledge we
have so far to perform applied research and provide forecasting for specific
problems. For example, at MSSL we are working on practical applications of
solar and space plasma physics for space weather users. First, we have two
contracts part funded by the insurance industry as part of the Tsunami
initiative, one to study satellite failures and the other to build a ‘black
box’ detector for commercial satellites. Second, we are working with Virgin
Atlantic Airways to measure and understand radiation in aircraft cabins.

In this presentation we will look at four main questions: (1) what is space
weather? (2) what causes space weather? (3) what effects does space weather
have? and (4) what are we doing about space weather?

Along the way we will see spectacular movies of the Sun’s effects, look at
the effects of huge solar disturbances including this year’s record solar
flare, look at exciting new results from Cluster and see what is the ‘state
of the art’ in space weather prediction. Also, for the first time in public
we will present results from our work on space environment prediction and
diagnosis for the satellite insurance industry.

Key finding

The key finding to be presented (although much of the talk is general) is
that we can, with a reasonable level of skill, predict the intensity of
‘killer’ electrons in the Earth’s radiation belts using only a few measured
parameters, and therefore predict and analyse dangerous conditions for
satellites.

New and interesting

Even after decades of study, only a few aspects of space weather can be
predicted. ‘Killer’ electrons can cause danger for satellites on which we
depend in our daily lives. A new website which can now predict dangerous
conditions for satellites, using a ‘red/amber/green’ traffic light system,
will be unveiled. In addition, new results from Cluster will be presented
which will help us understand the magnetic shield’s response to space
weather events and we will show results from Cassini which reveal the
effects of solar activity near Jupiter.

Relevance to general audience

We depend on space for communications, weather forecasting and positioning
on the Earth’s surface. Each applications satellite costs some $250 million
and is insured. We have an increasing volume of air travel and a tendency
to use higher altitudes and polar routes. All of these can be affected by
space weather, making this an important and relevant topic.

Next step

The next step is to improve the skill of predictions and to broaden the
range of space weather effects that can be predicted.

Others working in area

Many research groups are active in solar and solar-terrestrial physics (see
RAS MIST webpage at http://www.nerc-bas.ac.uk/public/uasd/mist.html, solar
groups listed at http://www.mssl.ucl.ac.uk/www_solar/solarlinks.html ). UK
groups are playing lead roles on the SOHO, Cluster and Yohkoh missions and
are involved in many other space missions and are also strong in data
interpretation, modelling and theory.

Several UK groups are involved in space weather related work. The studies
at MSSL involving the insurance industry and airline companies are
particularly relevant to the BA meeting theme ‘Science and Society’.

[NOTE: An image supporting this release is available at
http://www.mssl.ucl.ac.uk/pages/news/spaceweather07Sept01/assets/images/sample_page.JPG]

Contacts:

Dr. Andrew Coates, ajc@mssl.ucl.ac.uk

phone: 01483 204145 fax: 01483 278312

BA meeting website: www.indigowebdev.com/the-ba/page.asp

MSSL website: www.mssl.ucl.ac.uk

MSSL switchboard: 01483 204100

SpaceRef staff editor.