Press Release

Envisat – the detail’s in the data

By SpaceRef Editor
January 23, 2002
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In a cool, air conditioned room on the ground floor of a modern building
on the outskirts of Rome, a young scientist is carefully handling a
“pizza”. But this “pizza” is certainly not for eating. It’s the term
coined by researchers at ESRIN, the European Space Agency’s centre in
Italy for the large rectangular cassettes on which information from space
is soon to be stored.

Containing 1.7 km of tape, these “pizzas” will hold the huge amounts of
data that will shortly stream down from Envisat, the environmental
monitoring satellite from the European Space Agency, slated for launch at
the end of February 2002. Perhaps the most complicated satellite the
Agency has ever launched, Envisat will look down on the Earth with an
unparalleled array of complex instruments. But it’s not just the
complexity of the instruments that’s exciting scientists all over Europe.
Many say it’s more the quantity and quality of the data that will flow
from Envisat that’s the real cause of scientific interest.

For scientists involved in climate research, the belief is that the data
in the “pizzas” will resolve some of the outstanding issues in global
climate change. If this happens, say the scientists; they have no doubt
that Envisat will also directly impact the actions of politicians at both
national and European level.

Mark Doherty, head of the exploitation division at ESA/ESRIN is highly
confident about the impact of Envisat. “Robust reliable global
environmental information is going to be an economic, political and
eventually a security must within the next 5 to 15 years. It’s going to be
red hot. And Europe must have the capability to get this information.” He
believes that Envisat can deliver this valuable resource not just for
scientists and politicians but for citizens as well. So what convinces
hard headed scientists like Mark Doherty that a lone satellite can so
change the world we live in? It’s the simple faith that good science can
lead to political decisiveness and informed public opinion. And this
belief is based on the bedrock of good data.

Most scientists, whatever their field, will concede that although they
seek truth, they do not know it or even generate it. The only thing that
science really has is observable evidence. As Francis Bacon said almost
400 hundred years ago: “For man is but the servant or interpreter of
nature, what he does and what he knows is only what he has observed of
nature’s order, in fact or in thought”.

But while evidence or data gives science the strength of its conclusions,
the nature of data can also weaken science and cast doubt on its ability
to characterise reality. Nowhere is this more evident than in relation to
climate change.

Let’s look at some of the outstanding areas of contention. Despite general
scientific agreement on the role of carbon dioxide in causing global
warming we are still uncertain about how much there is and how much is
absorbed by the seas and forests.

Prof. Hartmut Grassl is a former director of the World Climate Research
programme (WCRP). He says that our lack of scientific understanding about
the release and retention of carbon dioxide feeds into a much broader
political argument. According to Prof. Grassl, Envisat will provide an
independent and unbiased resolution to this problem.

“There is a sensor on Envisat which will give us the CO2 content of the
atmosphere – it’s an instrument called SCIAMACHY. This will be a major
breakthrough of our understanding of the carbon cycle. With this data we
could derive the sources and sinks of carbon. If you have the full content
of carbon in the atmosphere for a certain place and you measure it every
few days, you can run a model and ask it how strong was the net source or
sink of carbon over Germany or Britain or the Atlantic. By combining your
model with information from Envisat, you would be able to say if the
German forest is really a sink of carbon in the summer – this is a good
example of the use of science data for a political decision.”

This could have a major impact on current political negotiations.
Arguments over the levels of carbon sequestration are dominating the
negotiations between the parties implementing the Kyoto Protocol.
According to Jos Delbeke, one of the leading negotiators for the European
Union and director of the European Commission’s climate change department,
the promise of the Envisat data could really help the politicians.

“Satellite data in general are pretty weak except for carbon dioxide
emissions. Non CO2 gases and carbon sequestration are the areas in which
we have major uncertainties and indeed even methodological problems – But
if we can get a regional and global picture on sequestration from the
SCIAMACHY instrument that would be a major advantage. There are lots of
questions on which we have not got good information and not even a good
methodological basis, and this Envisat methodology could be useful for

As well as breaking new ground with instruments that are state of the art,
Envisat will also impact because these instruments will work together in
unprecedented ways. And for scientists the ability to have different data
from different instruments, all working together is very exciting.
According to Dr. Bryan Lawrence, head of the British Atmospheric Data
Centre at the Rutherford Appleton Laboratories, this will be a key
advantage of the data from Envisat.

As an example, he points to the ongoing problems with Ozone. Despite
successes in recent years in removing chloroflourocarbons or CFCs from the
environment, Dr. Lawrence says there are still huge gaps in our
understanding of the Ozone layer. “People keep saying that Ozone is a
solved problem, we have these international agreements and it’s all over
now, we just have to wait for this stuff to get out of the atmosphere.
It’s just not that simple. We don’t know about the chemicals that have
replaced CFCs. Are they really that safe? Everyone thought that CFCs were
safe, for 60 – 80 years they were the safest things going, you could drink
the things, and they were that safe! Except nobody knew about his or her
impact on Ozone. With some of the replacements we already know we don’t
understand the chemistry as well as we should. Envisat will give us
instruments that will measure the chemistry with unprecedented resolution
and it’s the synergy of having those measurements that will be
significant. Again it’s the synergy of the data that will make it

These are just some of the controversial scientific questions that Envisat
will attempt to answer. But what makes Envisat’s answers different from
any one of a dozen other space based platforms? It’s the data. The
quantity, quality, and evaluation of which break new ground for an earth
observing satellite.

Envisat has ten instruments that will churn out a huge range of data.
Every day enough data to fill the hard disks of hundreds of PCs will be
beamed down to earth, collected via listening stations and assembled at
ESA/ESRIN in Rome. According to Olivier Arino, who heads the project
section developing application products for institutional users at ESRIN,
Envisat is unique in data terms. “It is the only one that will be
providing, operationally in near real time, the bunch of data required by
institutions to monitor the Kyoto protocol implementation and other
environmental treaties”. But size isn’t everything. According to Mark
Doherty, sometimes small amounts of data can give you vital information.
“The altimeter on Envisat for instance can measure changes in sea surface
level in centimetres, so if you want to monitor where sea levels are
rising, this is essential. This instrument produces small amounts of data
but the value of the information far outweighs the amount of data. The
data amounts are interesting but its much more interesting to know the
insights and the global vision that you get from them.”

Data in whatever quantities can be very useful for scientists but only if
it is reliable. There have been controversies in the past where
information from satellites has not matched up to observations taken from
the Earth. So how will ESA ensure that Envisat’s data is trustworthy? “As
a matter of credibility we are co-ordinating with a world wide
organisation, the Committee on Earth Observation Satellites”, says
Yves-Louis Desnos, who manages the scientific projects of Envisat at
ESA/ESRIN. “We ensure current data sets between the different earth
observation missions, from NASA and ESA and others. We have financed a
ship campaign in Miami, where we put on the same ship all the instruments
used to calibrate and validate the measurements of the ocean temperature.
With this information we can ensure that the measurements made by Envisat
or by American satellites have the same traceability and are calibrated
with each other. This allows us to be able to monitor ocean temperature
variation over ten years with an accuracy of 0.3 degrees. Then we can
monitor trends in the global climate with confidence.”

Many other scientists across Europe are involved in this calibration and
validation process. Dr Ian Robinson from the School of Ocean and Earth
Science at Southampton Oceanographic Centre explained how he will ensure
the accuracy of the information coming from the MERIS instrument. This
medium resolution imaging spectrometer takes images of the sea surface and
clouds and is able to see the colour of the ocean over ten wavelengths,
“it lets us see not just what our eyes would see but much, much more” says
Dr. Robinson.

He is calibrating the measurements himself using information from other
sources such as buoys and ships and will compare the initial data from
Envisat to these.

Ian Robinson also says that this time, ESA have really got ahead of the
game when it comes to processing the information. “ESA are geared up more
than ever before to swing into action, the algorithms are ready and
waiting to receive the data for things such as chlorophyll measurements
which is really important because it tells us how much CO2 is in the sea.
They’ve had plenty of trial runs with dummy data sets. We know that the
systems are in place.”

Bryan Lawrence stresses that “Essioas spent a lot of money on validation
of Envisat data. There’s a big programme with a much higher priority than
before. Scientists will be able to have much more confidence in the data.
ESA has got the planning right.”

Speed and immediacy of information are also critical. Yves-Louis Desnos
says that the near real time capability of Envisat will make a very big
difference. “Before you had to image a site and wait 35 days before
getting data. If you wanted readings from different instruments it would
be even longer. Now with Envisat we can have simultaneous observation of
say, sea surface temperature, with high accuracy, we can monitor the waves
on the ocean and the forests over land – and all this at the same time!”

The prospect of all this data is proving a splendid appetiser for European
scientists. So far over 700 have applied to work with the information that
will flow from Envisat. But given that there is so much data, and so many
hungry scientists wanting to get their hands on it, how will the
information flow smoothly from space to the lab?

A critical aspect according to Bryan Lawrence is the application of
Internet technologies for distribution. He believes that the Grid will
make a big impact on the flow of data. The Grid is a more complicated form
of the Internet that uses the processing power of all the computers
connected to a network to vastly increase the abilities of any one
machine. “What’s happening is that the research community is starting to
use tools developed by computer scientists and network communities to make
things happen in ways that are cheap and fast, instead of having to build
a multi-billion Euro infrastructure to move the information around. It’s
simply the bandwith – with the Internet now and the Grid in the future,
and the fact that it’s prevalent and pervasive.

Jean Paul Malingreau is an adviser in the Joint Research Centre of the
European Commission. This is a separate directorate that provides the
scientific advice and technical know how to support EU policies. He agrees
that the present flow of data from present space missions into the hands
of politicians is very slow. “It is slow, for various reasons, the issues
are rather complex, and scientists have to convey the complexity of the
issues and often there is uncertainty over the causes particularly in
relation to climate change. What is clear is that there is more in the
research output than reaches politicians and the public – In terms of
satellite data collection there is a lot of it that is not used to optimum

He says that politicians now have far more awareness of the need for good
data particularly in the years ahead when negotiations over the
environment will intensify and accurate ways of checking up on agreements
are desperately needed. “It’s certainly true we would like to see more of
the research being used and the politicians would like to have more of the
research on standby, if you like, in the course of negotiations or in the
course of making decisions.”

Members of the European Commission according to Malingreau will warmly
welcome Envisat. “Envisat is a formidable machine, it’s of a highly
complex nature, with ten instruments on board and will provide a broad
variety of data and information on a variety of parameters which are
important for the evaluation of global change. I think it will have
significant impact on the research and on the progress on understanding
the phenomena of global change. When that is done it must still be
conveyed to politicians, but its part of a chain of information. And good
input equals a good result.” Scientists say that Envisat offers a unique
new development that will make a greater impact on the political process.
It is user driven. Bryan Lawrence says that Envisat will be “more
responsive to end user demands”. Oliver Arino from ESA/ESRIN says that he
and his colleagues are now talking to EU politicians and planners,
particularly the Environment Directorate of the European Commission. “We
are trying to find out at EU level what their needs are.”

He quotes the example of the EU wide directive on the use and conservation
of water. “Envisat can give a regional picture across the EU. They can get
information from national governments but they need an instrument that can
allow them to make comparisons across the whole of the EU. Data from
Envisat is the only way to provide it”.

And it is not just at the European level that Envisat is set to make an
impact. At national level Envisat data will be used to ensure that
countries are keeping their commitments under the Kyoto Protocol. And the
word has spread down from governments to political and civil institutions.
Olivier Arino quotes the example of the Italian civil protection
authorities. “They came and saw us in ESRIN, and asked us to demonstrate
the ability of Envisat to map burnt forests, something that’s a legal
requirement in Italy. These people are ready with finance to access this
information when we can deliver it”.

The launch of Envisat is coming at a good time when both politicians and
scientists are aware of the capabilities of the satellite and both are
hungry for its information for different purposes. But according to Jos
Delbeke, of the EU’s Climate Change department, scientists must overcome
one big hurdle if they want their data to really impact the political

“Science has an open recognition of the uncertainties in the system. We
have to have the courage to sum up from time to time and to build on a
majority view of scientists to communicate to the politicians where we
stand. If we are going to wait for a final answer from science, for a 100
percent consensus, I think we are waiting for Godot. If everything is
uncertain then politicians won’t be able to sort out issues on which we
can already act. So increased levels of confidence by scientists in their
data would help the political process enormously.”

According to Bryan Lawrence this is a core strength of the Envisat data.
“People will only need to know what they want, not how to get it. All they
need to do is ask the right questions, they won’t need to know how to get
to the information to answer them – I may never be able to give a
politician a black or white answer, but thanks to the complexity and speed
of the data from Envisat, I’ll certainly have far more confidence in my

Another key point for the acceptance of Envisat data on a political level
is that it must make “a real difference to real people” according to Ian
Robinson. “Its payback time. Scientists have been funded for many years to
develop an understanding of the oceans, now that we can measure surface
temperature, and the colour, etc. it’s time for society to benefit.
ENVISAT will also be useful when it comes to things like algal blooms and
detecting waves and monitoring pollution and oil spills. In these real
time scenarios ENVISAT will make a real difference to people.”

And even if science and politics cannot solve all the problems of the
environment, Ian Robinson says there is one overwhelming reason why data
from Envisat will have a global impact. “It’s all about the continuity of
data. We owe it to the world to go on collecting the statistics. In many
ways we’ve only just begun and we need to go on to the next generation. We
may hand our children an environmental mess but at least we can have
accurate data with which to develop solutions. It’s our moral duty to
collect this data and hand it on”.

Note to Editors: This information note is the fourth of a series devoted
to the Envisat programme and its applications. Pictures relating to
Envisat are available in low and high resolution on the ESA web at (under Image Gallery), or in the electronic version of
the relevant information note.

For further information, please contact :

ESA Media Relations Office

Tel. + 33 1 5369 7155

Fax. + 33 1 5369 7690

SpaceRef staff editor.