On 19 October 50 racing cars will be in Darwin, Australia warming up for the
start of the 7th World Solar Challenge. Among them, a slick student-built
machine that profits from space technology supplied by ESA. The Dutch Nuon Solar
Team and their car Nuna II is among the favourites and ready to defend the title
won by their predecessor Nuna in 2001.

In the 2001 World Solar Challenge Nuna, the first Dutch solar car to use
European space technology, crossed the finishing line first after a grueling
3010 km race across Australia. Nuna won in a record-breaking time of 32h39m,
beating the previous record set by the Honda team in 1996 of 33h32m. Another new
record was set by Nuna’s average speed of 91.81 km/hour compared to the Honda
team record of 89.76 km/h. Nuna also pushed the limits by finishing in just
under 4 days.

"Of course we will try to be first again," says Koen Koster of the student’s
team. "We aim for an average speed of 100 km/h and to finish within 30 hours. It
will be tough though as we will be strongly challenged by the 2001 runner-up,
Aurora 101, one of the eight Australian teams and the 1999 winner. Other
high-budget teams vying for the lead are US Principia College, Queens University
from Canada and the Japanese team."

"If we win, in part it will be due to the use of space technology," explains
Diederik Kinds, an aerospace engineering student at the Delft University of
Technology and leader of the Nuon Solar Team. "Our car uses the most advanced
space technology, provided to the team via ESA’s Technology Transfer Programme.
This should enable the car to reach a theoretical top speed of 175 km/h compared
to Nuna’s top speed of 160 km/h.

"We strongly improved the aerodynamics by lowering the canopy and reducing the
car’s bodyweight by using lightweight space-plastics. The main body is made from
carbon fibre, reinforced on the upper side and on the wheel’s mudguards with
aramide, better known under the prodict name of Kevlar."

Carbon fibre is commonly used in the space industry for constructions that have
to be both lightweight and strong. One use of Kevlar is in spacesuits to protect
against micrometeorites. On Nuna II Kevlar is used to shield against the impact
of gravel during the race.

"Most important are the solar cells," continues Kinds, "we use solar cells that
harvest up to 20% more energy than those used on Nuna for the 2001 race."

"The solar cells used on the top and the sides of the car are triple-junction
gallium-arsenide cells made in three layers. Sunlight passing through the top
layer is captured by the second and the third layer. These solar cells are such
a recent development that not even ESA has used them yet. Their first space
application will be when the SMART-1 lunar mission is launched in September.

"Nuna II is fitted with 3000 solar cells" continues Kinds. and their output is
optimised by 10 Maximum Power Point Trackers." These have been used in
satellites for years as they optimise the output of the solar panels when
satellites pass into the shade due to their position in relation to the sun.

Nuna II will also occasionally be in the shade, due to clouds, buildings and
overtaking trucks which reduce the efficiency of solar cells. Maximum Power
Point Trackers will ensure that energy from the solar cells remains high and
constant. A chip will measure the voltage supplied by the solar cells, compare
it with the fixed battery voltage and then determines the best voltage to charge
the battery. In this way more than 95% effiency can be attained.

"In poor weather high-performance batteries are needed and these are also based
on space technology. Those on board Nuna II have 46 large Li-ion cells connected
in series to supply 5 kw/h of electrical energy. Again these were originally
developed for use in satellites where high reliability is essential. Their first
space application will also be on the SMART-1 lunar mission.

"Last but not least, our captain of communications is astronaut Wubbo Ockels,"
adds Koster with pride. Ockels, ex-ESA astronaut now head of ESA’s Education
Office and Professor of Manned Spaceflight at the Technical University of Delft,
led the first Nuna team to victory in 2001.

"Will Nuna II win? I think the team has a very good chance," says Ockels, "It
will be a tough race as driving from Darwin to Adelaide in October means
traversing 3010 km of Australian desert during the start of the hot season. It
will be a four-day battle against the elements. As in 2001 we will send a car in
advance to warn of any obstacles on the road. The rest of the team and I will
follow Nuna II in a support vehicle collecting data about the temperature and
current from the solar cells.

"This information will help the pilot to determine strategy, such as whether it
is better to drive quickly to escape cloud cover or to drive slowly to save
energy. Also we will study the very latest images from weather satellites and
meteo bulletins. Selecting the best racing strategy should help us to gain on
the other teams."

After crossing Australia in 2001 Nuna then toured Europe visiting schools and
museums in 35 cities in 12 European countries. This educational programme
emphasized the value of space technology for a more sustainable world and
showed, in a tangible way, how the dreams of youngsters can become reality.

In May 2004 Nuna II will ride again, this time in Greece in the Phaeton 2004
rally for solar cars, an initiative of the Cultural Olympiad 2001-2004. For the
first time during an Olympics solar cars, made by young scientists from all over
the world, will take part in a rally. The rally, which starts and ends in
Athens, will visit historic sites such as Olympia and Delphi, sending a clear
message that human activities should be exercised in respect of nature.

"Most important," adds Ockels, "is that the cars are designed and driven by
young scientists who are inspired and motivated by such events. In Australia the
Nuna II team will demonstrate this inspiration and motivation. No wonder we are
again one of the favourites to win the race."

Related news

* Nuna — coming soon to a town near you

* Nuna wins the World Solar Challenge!

* Solar Challenge rally benefits from space technology

Related links

* Nuon Solar Team

* World Solar Challenge 2003

* Solar car race Phaeton 2004

* Introduction to the SMART-1 mission

* Technology Transfer Programme