SMART-1 manoeuvres bring Moon impact to nearside
Wed Jul 19, 2006 at 20:04 UTC
On 2 July 2006, mission controllers successfully completed a two-week manoeuvre campaign designed to adjust the orbit for a nearside impact, to maximise science returns at mission end.
On 19 June, SMART-1 mission controllers at ESOC, ESA's Spacecraft Operations Centre in Darmstadt, Germany, initiated a two-week series of thruster firings aimed at optimising the time and location of impact on the Moon's surface. Disposal via impact is a method adopted by many previous missions and will provide an opportunity to gather science results related to impact effects.
The recently completed manoeuvres comprised 520 reaction-wheel off-loadings using the attitude thruster during 66 orbits, fewer than the 74 orbits initially planned. 'Off loading the reaction wheels' involves using a set of wheels spinning inside the spacecraft together with thruster firings to effect a change in momentum, and hence the velocity, of the spacecraft.
The resulting accumulative change in velocity has shifted the time and location of impact, which, before the manoeuvres, was due to occur in mid-August on the lunar farside; impact is now set to occur on the near side and most probably at 05:41 UT (07:41 CEST) on 3 September 2006.
"Mission controllers and flight dynamics engineers are analysing the results of the manoeuvre campaign to confirm and refine this estimate," says Octavio Camino-Ramos, SMART-1 spacecraft operations manager (SOM) at ESOC, adding, "adjustment manoeuvres are planned on 27 and 28 July, 25 August and on 1 and 2 September."
Image Credit: ESA - C.Carreau
This artist's impression shows the trajectory of ESA SMART-1 spacecraft in the final phase of its mission, due to end through a small impact on the lunar surface.
After two weeks of manoeuvres started on 19 June and concluded on 2 July 2006, the impact is now set to occur on the near side and most probably at 05:41 UT (07:41 CEST) on 3 September 2006.
The manoeuvre just concluded, and the definition of the SMART-1 trajectory, also provide an important piece information for the professional and amateur observers worldwide willing to perform coordinated lunar observations with SMART-1 and to participate in observing the spacecraft's impact.
"We are calling upon astronomical observatories and amateurs worldwide to participate in a coordinated observation effort with SMART-1, including the final orbits until impact," says Bernard Foing, SMART-1 Project Scientist. He adds that, "In the orbits prior to the expected impact, between 19:40 UT (21:40 CEST) on 2 September and 00:40 UT (02:40 CEST) on 3 September, the spacecraft will pass less than 2 kilometres above the lunar surface - based on the known lunar topography - and there is still a possibility of premature impact if some unknown peaks are in the way."
ESA News Release
