Newsgroup: it.fan.startrek
Titolo: Smart-1

http://www.timesonline.co.uk/article/0,,3-1354660,00.html
'Star Trek' spaceship enters the gateway to the Moon
By Mark Henderson, Science Correspondent
A EUROPEAN spacecraft powered by a Star Trek-style thruster has flown
through a “lunar gateway” that puts it on course to reach the Moon on
Monday.
Smart-1 has fired its revolutionary ion engine to reach a point at which it
can be captured by the Moon’s gravity.
Yesterday morning the washing machine-sized probe cleared the “Lagrangian
point” at which the gravity of the Earth and the Moon are in perfect
balance. The craft is now assured of orbiting the Moon.
“Smart-1 has passed through the gateway to the Moon,” said Bernard Foing,
of the European Space Agency (ESA), the probe’s chief scientist. “It’s an
important symbolic day.”
Had the ion drive fallen just 5 per cent short of maximum thrust, Smart-1
could have collided with the Moon.
The probe is about 37,000 miles (60,000km) from the Moon. Shortly before
6pm GMT on Monday, when it will be about 31,000 miles away, mission control
will start up the engine again for 4½ days. This will guide Smart-1 into a
final orbit between 185 miles and 6,200 miles above the lunar surface. It
will then begin at least nine months of observations that will shed light
on what the Moon is made of and how it formed.
Smart-1, which cost £77 million to build, was designed primarily to test an
ion drive propulsion system that has the potential to cut years off the
flight time to Mercury and Mars and other planets.
The engines are ten times more efficient than standard chemical rockets.
They work by using electricity from solar panels to charge atoms of the
noble gas xenon, which are then fired into space at 1,000mph to power the
probe.
This stream of ions accelerates Smart-1 at just 0.2millimetres per second.
In space, this builds up over time to generate speeds of up to 10miles per
second, or 36,000mph.
Because its initial speed was so low, Smart-1, which was launched last
September from Kourou in French Guiana, has taken 14 months to reach the
Moon.
The journey time to more distant targets will be significantly shorter.
BepiColombo, a European probe that will fly to Mercury in 2009, will arrive
there in 2½ to 3½ years if it can use ion propulsion, rather than in 6 to 7
years using conventional engines.
Lunar missions such as Smart-1 have the potential also to reveal what the
Earth was like in its youth.
One of Smart-1’s most important instruments for gathering this information
will be D-CIXS, an X-ray spectrometer built mainly by British scientists
that will show the elements that exist on the Moon.
Jolan Tru
-- 
Filippo "Hytok" Simone - L'oracolo sampdoriano di Sunnydale
La Casa degli Elfi - 
http://www.freewebtown.com/lacasadeglielfi/
Enclave del Dominio - S.N.S. Despiser - 
http://ildominio.altervista.org/
Commissione Voyager - 
http://www.voyageritalia.com/

Moon.
Questa non l'ho capita.........................14 mesi per raggiungere
la Luna???
< 1d4 >


L'energia per alimentare il propulsore ionico viene presa dalle celle
fotovoltaiche, senza contare che non e' stata lanciata con un Saturno 5.
:-)
Il vantaggio della propulsione ionica e' che la resa e' elevatissima
rispetto ai propulsori "normali" (che "dentro" il combustibile portano
con se la massa E l'energia chimica per produrre la spinta, mentre
un propulsore ionico ha solo bisogno di roba che gli fornisca massa
da espellere).
Inoltre rispetto ad un propulsore "chimico" si ha un controllo
molto preciso anche con spinte molto piccole (quindi si perde
meno energia e massa a correggere la rotta a causa degli
"errori di spinta").
A parte la lentezza, significa che se puoi spedire ad esempio 100Kg
in orbita, con un propulsore a ioni hai piu "carico utile"
per strumenti ed altra roba da porre in orbita o da sganciare
sulla Luna.
Il vantaggio e' enorme visto che nelle missioni spaziali
il costo sta tutto in quanto costa portare a destinazione
una certa "massa utile", mentre il tempo e' secondario
se non ci sono persone a bordo.
L. Micheletto

se non ci sono persone a bordo.
Però in dieci anni porterai a termine molte meno missioni, o sbaglio?
< 1d4 >