Hayabusa (Muses C)

Launch data: Designation  27809 / 03019A Launch date  09 May 2003 - 04:29:25 UT Launch site  Uchinoura Space Center Launch vehicle  M-V-5 Mission  Asteroid Itokawa probe Heliocentric orbit Perihelion / Aphelion   Incl. to ecliptic   ° Period   min

Spacecraft data: Prime contractor   Platform   Operator  JAXA Mass at launch  530 kg, including 50 kg of chemical propellant and 65 kg of xenon gas. Dry Mass   kg Basic shape  box-shaped Dimension  Core 1m x 1.6m x 2m Solar array  5.7m full width at deployment of solar paddle Stabilization   DC power

Decay: Descent date main spacecraft:  13 Jun 2010 - 13:52 UT Cause:  burnt up in atmosphere Descent date return capsule:  13 Jun 2010 - 14:12 UT landed in the Woomera range Lifetime:  7.1 years

Description:

• The primary scientific objective of the Hayabusa (formerly Muses-C) mission is to collect a surface sample of material from the small (550 x 180 meter) asteroid 25143 Itokawa (1998 SF36) and return the sample to Earth for analysis. It is also a technology demonstration mission. Other scientific objectives of the mission include detailed studies of the asteroid's shape, spin state, topography, color, composition, density, photometric and polarimetric properties, interior and history.
• The Hayabusa spacecraft has a box-shaped main body 1.5 m along each side and 1.05 m high. The launch mass is 530 kg, including 50 kg of chemical propellant and 65 kg of xenon gas. Two solar panel wings with a total array area of 12 square meters protrude from the side and a 1.5 m diameter high-gain parabolic antenna is mounted on top on a two-axis gimbal. A cylindrical sampler horn, deployed shortly after launch, protrudes from the bottom of the spacecraft. The Minerva lander was also mounted on th spacecraft near the bottom panel. Hayabusa is propelled during cruise phases by two microwave ion thruster engines, which use a microwave discharge to ionize xenon gas. The ionized plasma is accelerated by high-voltage electrodes through four thruster heads which protrude from one side of the spacecraft body to provide a peak thrust of 20 mN using 1 kW power. A nitrogen tetroxide/hydrazine propulsion system with a peak thrust of 22 N will be used for maneuvering. The spacecraft is powered by gallium-arsenide solar cells and a 15 A-hr rechargeable nickel-metal hydride (Ni-MH) battery. Communications are via X- and S-band low gain antennas and the high gain dish antenna (X-band) with a transmitted power of 20 W. The mission is also be equipped with a camera, used for imaging, visible-polarimetry studies, and optical navigation near the asteroid, a laser ranging device (LIDAR), and near-IR and X-ray spectrometers. The insulated and cushioned re-entry capsule, 40 cm in diameter and 25 cm deep with a mass of about 20 kg, is attached to the body of the spacecraft near the sample collection horn. The capsule has a convex nose covered with a 3 cm thick ablative heat shield to protect the samples from the high velocity (~13 km/s) re-entry.

Mission:

• The spacecraft was launched on 9 May 2003 at 04:29:25 UT (1:29 p.m. local time, 12:29 a.m. EDT) on an M-5 solid fuel booster from the Uchinoura Space Center. Following launch, the name Muses-C was changed to Hayabusa (the Japanese word for falcon).
• The M-V third stage reached a suborbital trajectory of around -185 x 500 km, and the KM-V2 kick motor then accelerated Hayabusa into an escape orbit which resulted in a solar orbit and separated. The ion drive began operating and by Jan 2004 the solar orbit was 0.860 x 1.138 AU x 1.2 deg.
• This should leave three objects in space: MUSES-C and its KM-V2 kick motor, which have been cataloged as 2003-19A and 19B, both in solar orbit, and the M-34 third stage in Earth orbit.
• It will use solar electric (ion) propulsion to rendezvous with minor planet (25143) 1998 SF36 in Sep 2005 and return a sample to Earth.
• The ion engines were successfully test-fired starting on 27 May to the middle of June, 2003. A large solar flare in late 2003 degraded the solar panels. The loss of power available to Hayabusa's ion engines forced the originally planned early summer 2005 rendezvous with Itokawa to be moved back to September.
• A 3725 km Earth flyby on May 19, 2004 at 06:23 UTC pumped up the orbit to 1.01 x 1.73 AU x 1.3 deg, adjusted by Jul 2005 to 0.95 x 1.70 AU x 1.6 deg, matching Itokawa.
• On Aug 24, 2005 Hayabusa was 8880 km from asteroid Itokawa; by Sep 2 it was at only 1550 km. It reach asteroid (25143) Itokawa on Sep 12, 2005 stationkeeping at 20 km at 01:17 UT.
  
  

  Image of asteroid Itokawa taken by Hayabusa. Credit: ISAS, JAXA

  
  
  
• After maneuvering around the object, despite a reaction wheel failure on Sep 30, 2005 Hayabusa approached to only 70 metres from the surface on Nov 9, 2005 and then retreated; in a second descent that day, to 500 m, it released a small target marker, which failed to land on the asteroid.
• On 12 November 2005 a second rehearsal touchdown was attempted. The spacecraft began its descent from 1.4 km altitude at 3 cm/sec to an altitude of 55 meters. The small lander/hopper, Minerva, was deployed at 6:34 UT (3:34 p.m. JST) but unfortunately Hayabusa had already reached the 55 meter level and had begun an automatic ascent so the release was at a higher altitude than planned. Contact was lost and it is believed Minerva moved off into space without landing. Hayabusa then retired to its safe parking distance at about 5 km. The first of three 10-cm target markers was released on Nov 9, also into solar orbit.
• At 12:00 UT on 19 November 2005 (9:00 p.m. JST, 7:00 a.m. EST) Hayabusa began its descent towards the asteroid from an altitude of 1 km. At 19:33 UT (4:33 a.m. JST 20 November) the final approach was commanded and the descent began from an altitude of about 450 meters at 12 cm/sec. The target marker was released at 20:30 UT 19 November (5:30 a.m. JST 20 November) about 40 meters above the asteroid and Hayabusa's descent was slowed to 3 cm/sec to allow the marker to fall ahead of it. The spacecraft reduced its speed to zero and then began free-fall at an altitude of 17 meters at which point contact was lost. Later telemetry indicated that Hayabusa hit the surface at 20:40 UT 19 November (5:40 a.m. JST 20 November) at roughly 10 cm/sec and bounced. It bounced again at 21:10 and then landed at 21:30 within about 30 meters of the target marker. At 21:58 (6:58 a.m. JST 20 November) it was commanded to make an emergency ascent. The craft remained on the surface for about half an hour but did not collect a sample. This was the first ever controlled landing on an asteroid and first ascent from any other solar sytem body except the Moon.
• A second touchdown and sampling run was made on 25 November, early telemetry indicates the spacecraft touched down at 10 cm/sec and two sampling bullets were fired 0.2 seconds apart at 22:07 UT 24 November (7:07 a.m. JST 25 November) but examination of later telemetry indicates it is not clear that the bullets were fired.
• During takeoff, however, the spacecraft malfunctioned and entered safemode, and it's not yet known if any material was really captured. It was recontacted on Dec 5 at a distance of 550 km from Itokwawa, with its propulsion system only partly working. On 9 December contact was lost with the spacecraft, presumably because of torques caused by a thruster leak which altered the pointing of the antenna. Communications with the spacecraft were regained in early March 2006. It appears that the chemical fuel has been lost due to the leak, two of three reaction wheels are also inoperable and 4 of the 11 lithium-ion battery cells are not functioning. Ground controllers are using the solar batteries to run the ion engine, which will be used in place of the chemical thrusters to maintain attitude control. The ion engine ran until November 2007, at which time it was turned off and the spacecraft went into hibernation mode and continue on a ballistic trajectory. There is still a large margin of xenon left to run the thrusters for propulsion and attitude control. Earth return is scheduled for 13 June 2010.
  
  

  Asteroid Itokawa's image capturedNovember 20 by Japan's Hayabusa probe. Note shadow of spacecraft as it maneuvered to a close encounter with the space rock. Image Credit: ISAS/JAXA

  Collecting samples

  
  
  
• Hayabusa departed the Itokawa vicinity in Feb 2007 and, as contollers coaxed limited function out of its faltering ion drives, set course for Earth.
• On Jan 1, 2010 Hayabusa spacecraft is in solar orbit between Mars and Earth, and is targeting a midyear Earth return.
  
  
  
  
• By Apr 2010 it was in a 0.983 x 1.654 AU x 1.7 deg solar orbit at 24 million km from home, and began a series of course corrections to target it for landing.
  
  
  Credit: JAXA / ISAS
  
  
• Hayabusa entered the Earth's gravitational sphere of influence on Jun 11, 2010 and passed lunar orbit on Jun 12, approaching Earth on a hyperbola with an estimated perigee of -64 km, eccentricity of 1.37 and inclination of 34.5 deg. At 1051 UTC the conical Hayabusa return capsule separated from the main spacecraft. As they gained speed in their fall to Earth, the eastward motion of Hayabusa and capsule was initially slower than Earth's rotation and so their ground track headed west over the Pacific to around 60E 20N as their altitude dropped through 23000 km at 1300 UTC, and then, overtaking terrestrial spin, southeastward toward Australia. Nominal entry was at 200 km altitude at 1351 UTC, over about 125E 28S, travelling at 12.2 km/s at about -12 deg to the horizontal. The main spacecraft, with no heat shield, burnt up by 1352 UTC, as the reentry capsule decelarated and then descended by parachute. The capsule landed in the Woomera range area (Australia) at around 1412 UTC.
  
  
  
  

  Capsule with parachute on Earth

  Japan's Hayabusa asteroid sample return capsule sits on the ground in Australia before the recovery team begins the careful recovery process.

  
  
  

  A Japanese team recovers the Hayabusa mission's asteroid sample return capsule in a remote area of Australia.

  The sample return capsule

  
  Credit: JAXA / ISAS