SMART 1

Launch data: Designation 27949 / 03043C Launch date 27 Sep 2003 - 23:14:46 UT Launch site Kourou, ELA-3 Launch vehicle Ariane 5G (V162) Mission Lunar probe Earth Orbit on Sep 27.76: Perigee/Apogee 668 / 36008 km Inclination 6,95° Period 644,50 min Heliocentric orbit Perihelion x Aphelion   Incl. to ecliptic   Period

An artist′s concept of SMART 1 and its destination -- our moon. Credit: ESA

Spacecraft data: Prime contractor  Swedish Space Corporation with contributions from almost 30 contractors from 11 Eur. countries and the US. Operator ESA Platform   Mass at launch 370 kg Dry Mass 255 kg Dimension   Basic shape   Solar array   Stabilization   DC power   Decay date:  03 Sep 2006 Lifetime:  -

> Description of the sonde. Credit: ESA

On Sep 18, 2003 SMART-1 resting on top of the upper stage of the Ariane 5 launcher in the final assembly building at Kourou. Credit: ESA

Mission details:

• Liftoff from the Guiana Space Center on South America′s northeast coast occurred at 2314:46 GMT (7:14:46 p.m. EDT), nearly 13 minutes late to adjust the amount of cryogenic propellants in the rocket's main stage in an effort to "tune" the Vulcain 1 engine for the mission.
• The Indian Insat 3E and Eutelsat e-Bird communications craft were stacked atop SMART 1 for the ascent. After a 27-minute powered flight, the Ariane 5 achieved its planned geosynchronous transfer orbit, reaching a high point of 35,935 km for the target of 35,873 km, a low point of 649.5 km for a target of 648.7 km and inclination right on the mark at 7.01 degrees to the equator.
• Europe′s first lunar probe, launched for the European Space. Spacecraft is using electric propulsion to raise its orbit to one wich permits lunar encounter.
• SMART 1 will begin firing its ion engine Tuesday for epic journey to reach the Moon. The solar-electric propulsion system works by drawing 1350 watts of electric power from the satellite's solar panels to accelerate charged atoms of xenon through the engine, generating a thrust of 0.07 Newton -- the equivalent weight of a postcard. The onboard fuel supply is 82 kg of xenon gas.
  Although not operating constantly, the engine will be used over 16 months to propel SMART 1 into a highly elliptical orbit around the Moon′s poles in a complex, multi-step sequence.
  At first, it will fire almost continuously -- pausing only when is in the Earth's shadow -- to raise the lowest point of its orbit to 20,000 km. This maneuver will take about 80 days to complete.
  The planned selenocentric orbit is polar, 300-10000 km.
• SMART-1 lunar probe continues to operate its ion engine, with occasional flameouts at times of high radiation. On Nov 5, 2003 it was in a 3058 x 38624 km x 6.9 deg orbit compared to its initial 672 x 35829 km x 6.9 deg trajectory.
• SMART-1 lunar probe turned off its ion engine on Jan 30, 2004 for a period of payload commissioning. Launched into geostationary transfer orbit of 672 x 35828 km x 6.9 deg on Sep 27, 2003, its orbital period surpassed 23 hours in late January putting it in the geosynchronous region; the orbit is now 14312 x 59491 km x 6.9 deg with a period of 24h 53min.
  
  

  This illustration shows SMART 1 maneuvering from Earth to the Moon. Credit: ESA

  This illustration shows SMART 1 getting into orbit around the Moon. Credit: ESA

  
  
• The European ion-drive lunar probe, SMART-1, had by Jul 12, 2004 reached a 22361 x 155133 km x 6.9 deg orbit, having used about 41 kg of xenon propellant.
• The European SMART-1 probe made its third lunar resonance gravity assist on Oct 12, 2004 and on Oct 26 was in a 173339 x 298835 km x 20.6 deg deep Earth orbit. The continued gravitational effect of the Moon raised the orbit until lunar capture on Nov 15. On Nov 11 the spacecraft finally passed through the weak stability boundary region at the Earth-Moon L1 point, where small changes to the probe's path result in large alterations to its final orbit, and where the orbit becomes better described as Moon-centered rather than Earth-centered. The probe reached perilune on Nov 15 at 1748 UTC and entered a 4962 x 51477 km orbit around the Moon inclined at 81 degrees to the lunar equator. This is the most loosely bound lunar orbit ever achieved, with its highest point close to the Earth-Moon gravitational boundary - the US record-holder Explorer 35 in 1967 had an apolune of only 7800 km, while the 1990s Japanese probes Hagoromo and Hiten had apolunes of 22000 and 49400 km respectively; the Apollo missions went directly to low orbits with apolunes of only 300 km.
• SMART-1′s ion engine was restarted at orbit insertion to lower the orbital altitude and bind it more tightly the Moon; final orbit will be reached in January.
• Its ion engine has now lowered the orbit to 1014 x 5204 km x 87.9 deg.

Realisations:

• The main purpose of the first part of the SMART-1 mission, concluding with the arrival at the Moon, was to demonstrate new spacecraft technologies. In particular, the solar-electric propulsion system was tested over a long spiralling trip to the Moon of more than 84 million kilometres. This is a distance comparable to an interplanetary cruise.
• For the first time ever, gravity-assist manoeuvres, which use the gravitational pull of the approaching Moon, were performed by an electrically propelled spacecraft. The success of this test is important to the prospects for future interplanetary missions using ion engines.
• SMART-1 has demonstrated new techniques for eventually achieving autonomous spacecraft navigation. The OBAN experiment tested navigation software on ground computers to determine the exact position and velocity of the spacecraft using images of celestial objects taken by the AMIE camera on SMART-1 as references. Once used on board future spacecraft, the technique demonstrated by OBAN will allow spacecraft to know where they are in space and how fast they are moving, limiting the need for intervention by ground control teams.
• SMART-1 also carried out deep-space communication tests, with the KaTE and RSIS experiments, consisting of testing radio transmissions at very high frequencies compared to traditional radio frequencies. Such transmissions will allow the transfer of ever-increasing volumes of scientific data from future spacecraft. With the Laser Link experiment, SMART-1 tested the feasibility of pointing a laser beam from Earth at a spacecraft moving at deep-space distances for future communication purposes.
• During the cruise, to prepare for the lunar science phase, SMART-1 made preliminary tests on four miniaturised instruments, which are being used for the first time in space: the AMIE camera, which has already imaged Earth, the Moon and two total lunar eclipses from space, the D-CIXS and XSM X-ray instruments, and the SIR infrared spectrometer.
• In all, SMART-1 clocked up 332 orbits around Earth. It fired its engine 289 times during the cruise phase, operating for a total of about 3700 hours. Only 59 kilograms of xenon propellant were used (out of 82 kilograms). Overall, the engine performed extremely well, enabling the spacecraft to reach the Moon two months earlier than expected.

Astrophilately covers:

Launch cancel Kourou, numered cover.

Orbit cancel Noordwijk (centre ESA), numered cover.