* Astronomy

Blobrana · L

RE: HAYABUSA (MUSES-C) mission

Blobrana · L

RE: Hayabusa

Blobrana · L

RE: HAYABUSA (MUSES-C) mission

Blobrana · L

The Japanese robotic probe Hayabusa, formerly called Muses-C, is on a four-year, 600 million kilometres mission to bring back samples of asteroid Itokawa. If successful, it will provide the first material from space returned since the Moon rocks of the Apollo era.

Mission officials today announced that the probe had tracked the asteroid in a series of 24 images from July 29 to Aug. 12. The asteroid appears as no more than a point of light in the pictures taken by Hayabusa's star tracking camera, but seeing it is a milestone for the mission.

For almost two years and three months after the launch in May of 2003, Hayabusa spacecraft has travelled a long journey by way of Earth gravity assist in May of 2004, and will make the worlds first low thrust rendezvous with a near-Earth asteroid Itokawa next month.

Hayabusa performed the Star Tracker imaging of Itokawa on July 29-30, August 8-9 and August 12. Totally, 24 images were taken and the hybrid navigation combining both radio and optical measurement was performed and the results came out enough well to guide the spacecraft making a final approach to the object.
The optical navigation at very slow approach speed under ion engines propulsion is what Hayabusa has demonstrated for the first time. The exposure of Optical Navigation Camera (ONC), a high resolution imager, is also planned one or two weeks later.

Hayabusa carries three reaction wheels aboard. There was an incident on x-axis wheel, whose friction exceeded a driving torque on July 31 and stopped.
However, the spacecraft is designed equipped with Double-Reaction-Wheel (DRW) mode software, and taking the advantage of it, the spacecraft resumed the attitude stability and has been operated normally. The project team is confident in accomplishing a series of scientific observation including sample collection scheduled during the proximity phase.

The spacecraft is, as of August 12th, at about 35,000 kilometres at the very slow approach speed of 38 meters per second. This is peculiar to the low thrust rendezvous that has not ever been experienced.
The spacecraft will turn off the ion engines at the distance of 3,500 km to the object leaving intentional residual approach speed of 10 meters per second that is scheduled decelerated via Reaction Control System aboard. And in the middle of September, Hayabusa comes to still with respect to Itokawa at the distance of 20 km, Gate Position.

This shows Itokawa movements.
The constellation is Puppis, between the Canis Major (Great Dog) and the Carina.
However, Itokawa can not be seen toward that direction from Earth, but only seen via radio toward the Sun, which is too near Itokawa.
Itokawa seen from Hayabusa has increased quite rapidly its brightness up to the magnitude four.

After studying the asteroid for three months, Hayabusa will fire a bullet into the rock and collect ejected fragments. About two years later, it will parachute back to Earth.

Itokawa is a potato-shaped rock about 600 meters long. It is named after Hideo Itokawa, a Japanese rocket pioneer. NASA, which launched the probe, expects it to provide "a wealth of scientific return."

source

-- Edited by Blobrana at 23:53, 2005-08-15

Blobrana · L

The probe and nearby asteroid will pass behind the sun next month, restricting radio contact.
Images should start coming in once the radio interference clears up.

When Hayabusa was launched two years ago, mission planners expected the probe to be already at the asteroid by this time — but the schedule was delayed due to the heavy solar cell damage caused by the historical largest solar flare that occurred during the voyage in 2003.

The consequent reduction in electrical power from the craft’s solar cells caused Hayabusa's electrical propulsion system to lose thrust.

The delay has been worrisome, however, because there’s only one safe route home with the samples, and that requires the probe’s departure from the asteroid in mid-November.
For the kind of trajectory that the craft’s ion-powered engines can achieve, it’s a matter of leaving on time, or becoming a permanent asteroid resident.
Consequently, all the scouting and remote-sensing operations that had originally been planned to take three or four months must now be accomplished in half the time. This advance reconnaissance is essential if the actual landings — and several are planned — are to have any reasonable chance of success.

Asteroid 1998 SF36 measures about 500 metres wide, with a gravitational pull hardly more than a millionth of Earth’s. Itokawa's gravity is so faint that the probe won’t even bother to orbit the asteroid. Instead, it will hover about 20 kilometres away, surveying the surface both from the full sunlit side and then later from above the boundary between day and night.

Itokawa's shape and density are uncertain, and its 12-hour rotation period creates extra navigation hazards during the Hayabusa probe's slow approach.
Using small liquid-fuelled engines (rather than the low-thrust ion drive that serves during interplanetary cruising), Hayabusa will approach a pre-selected touchdown point. It will use a ranging laser to measure its approach range and speed, and half an hour before contact will deploy an optical sensor into the soil so that its camera system can sense any horizontal drift rates.
The first sensor, about the size of a softball, will carry almost a million names of people who supported the project.
The probe will contact the surface with a large "collection horn," and then it almost immediately will fire a bullet into the surface. Some of the material that scatters from the impact will make its way into a collection chamber, which will then be sealed. This process can occur up to three times at different locations.

Hayabusa will also deploy a small hopper robot named Minerva. This solar-powered mini-spacecraft will relay images from its three cameras to Hayabusa whenever the two vehicles are in direct line-of-sight contact.

Assuming the craft’s power system and four ion engines continue to function, the craft will return to Earth in July 2007. A special capsule will hit the atmosphere at 13 kilometres per second, and undergo forces of about 25 G’s before touching down in central Australia.
The material will be brought to a new national laboratory in Japan.
There it will be analyzed, and some of it will be shared with foreign investigators.

Blobrana · L

The HAYABUSA (MUSES-C) mission to the will investigate an S-type Asteroid (25143) Itokawa, an asteroid known as an earth-approaching type.

The Japanese spacecraft HAYABUSA will encounter Itokawa (1998SF36) on October - November this year, it will then drill into and retrieve a 1 gram sample to be returned back to Earth.

The spacecraft will also observe the asteroid with various scientific devices and measures. For that purpose, it is equipped with a Telescope Wide-View Cameras and Light Detection and Ranging, as well as with a Near Infrared Spectrometer. It will also employ a hopping robot, which can move around on the asteroid’s surface.
It will leave the asteroid in the summer of 2007.
It will then take about 4 years to return to the earth.
When HAYABUSA returns to Earth, a re-entry capsule bearing a surface sample from the asteroid will separate from it and plunge into the Earth’s atmosphere.

The spectral data of Itokawa corresponds to a LL5 or 6 chondrite.

HAYABUSA employs a highly efficient ion engine. This engine first ionizes the propellant gas, Xenon, then electrically accelerates and emits the ions, to propel it forward.

It was launched aboard a M-V-5 rocket on May, 9, 2003 from the Kagoshima Space Centre at Uchinoura (currently, Uchinoura Space Centre) Kagoshima. After launch, it was named “HAYABUSA” (Falcon).

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Its current Distance from Itokawa (on 8th june 2005) is 249,531km

                    Equatorial coordinates                                                                       
    Date      Hour        RA            DEC       Mag  Elong Phase Glat     R     Delta         
             (UTC)     h  m  s        d  '  "          (deg) (deg) (deg)   (AU)    (AU)    
 =========== ======  =============  ============ ===== ===== ===== ===== ======= ======= 
  9 Jun 2005  0.417    5 53 19.773  +23 51 54.20  22.4  10.3   6.8  -1.1  1.5316  2.5198   
 10 Jun 2005  0.417    5 56 10.725  +23 52 39.07  22.4  10.0   6.6  -0.5  1.5286  2.5185    
 11 Jun 2005  0.417    5 59  2.101  +23 53 12.30  22.4   9.7   6.4   0.0  1.5256  2.5171    
 12 Jun 2005  0.417    6  1 53.896  +23 53 33.79  22.4   9.4   6.2   0.6  1.5225  2.5155   
 13 Jun 2005  0.417    6  4 46.105  +23 53 43.45  22.3   9.1   6.0   1.2  1.5194  2.5139   
 14 Jun 2005  0.417    6  7 38.723  +23 53 41.22  22.3   8.8   5.9   1.8  1.5163  2.5123   
 15 Jun 2005  0.417    6 10 31.746  +23 53 27.01  22.3   8.5   5.7   2.3  1.5132  2.5105    
 16 Jun 2005  0.417    6 13 25.170  +23 53  0.73  22.3   8.2   5.5   2.9  1.5100  2.5087    
 17 Jun 2005  0.417    6 16 18.990  +23 52 22.31  22.3   7.9   5.3   3.5  1.5068  2.5067  
 18 Jun 2005  0.417    6 19 13.203  +23 51 31.68  22.3   7.6   5.1   4.1  1.5036  2.5047    
 19 Jun 2005  0.417    6 22  7.804  +23 50 28.75  22.2   7.3   4.9   4.6  1.5004  2.5027    
 20 Jun 2005  0.417    6 25  2.792  +23 49 13.46  22.2   7.0   4.8   5.2  1.4971  2.5005    
 21 Jun 2005  0.417    6 27 58.163  +23 47 45.72  22.2   6.7   4.6   5.8  1.4938  2.4983    
 22 Jun 2005  0.417    6 30 53.915  +23 46  5.47  22.2   6.5   4.4   6.4  1.4905  2.4960    
 23 Jun 2005  0.417    6 33 50.047  +23 44 12.62  22.2   6.2   4.2   7.0  1.4872  2.4936   
 24 Jun 2005  0.417    6 36 46.556  +23 42  7.10  22.2   5.9   4.0   7.6  1.4838  2.4912    
 25 Jun 2005  0.417    6 39 43.443  +23 39 48.83  22.1   5.6   3.9   8.2  1.4804  2.4887    
 26 Jun 2005  0.417    6 42 40.703  +23 37 17.75  22.1   5.3   3.7   8.7  1.4770  2.4861      
 27 Jun 2005  0.417    6 45 38.336  +23 34 33.76  22.1   5.1   3.5   9.3  1.4736  2.4835    
 28 Jun 2005  0.417    6 48 36.338  +23 31 36.80  22.1   4.8   3.3   9.9  1.4701  2.4807    
 29 Jun 2005  0.417    6 51 34.705  +23 28 26.80  22.1   4.5   3.2  10.5  1.4667  2.4779    
 30 Jun 2005  0.417    6 54 33.433  +23 25  3.67  22.1   4.3   3.0  11.1  1.4632  2.4751