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Hayabusa 2

NSSDCA/COSPAR ID: 2014-076A

Description

Hayabusa 2 is a Japanese Space Agency (JAXA) mission designed to rendezvous with asteroid Ryugu (1999 JU3) and return a sample. The mission is similar in design to the first Hayabusa mission, but this will carry an impactor which will be used to create a crater and expose fresh material to be collected and returned to Earth for analysis. The mission launched on 03 December 2014 and the sample will be returned to Earth in late 2020.

Spacecraft and Subsystems

The Hayabusa 2 spacecraft is a modified version of the Hayabusa design. It has a box-shaped main body 1.0 x 1.6 x 1.4 m in size, with a total fueled mass of approximately 600 kg. Cruise propulsion is provided by four low-thrust (10 mN) xenon-ion-engines. Attitude control is achieved by 4 reaction wheels and twelve 20-N bipropellant hydrazine reaction control thrusters. Positional knowledge is provided by two star tracker cameras, four coarse Sun aspect sensors, two inertial reference units, and four accelerometers. For asteroid proximity operations, the spacecraft has three optical navigation cameras, LIDAR, and a laser rangefinder. Two solar panel wings with a total array area of 12 square meters protrude from the side, supplying 2.6 kW at 1 AU and 1.4 kW at 1.4 AU. Power is stored in a 13.2 AHr lithium-ion battery. Communications take place through two 1.5 meter high-gain antennae (one X-band (8 GHz, 32 Kbps) and one Ka-band (32 GHz, 32 Kbps)), a steerable two-axis gimballed X-band medium gain antenna, and three X-band low-gain antennae.

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. A one meter long cylindrical sampler horn, deployed shortly after launch, protrudes from the bottom of the spacecraft. There will also be a sampler comprising a sticky material which will be pushed against the surface to collect dust. 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.

Also mounted on the spacecraft are the MASCOT lander, the Small Carry-on Impactor (SCI), the Deployable Camera (DCAM3), the re-entry capsule, three small (1.5 kg) MINERVA-II rovers, and five targets. The science payload consists of a Thermal Infrared Imager (TIR) and a Near Infrared Spectrometer (NIRS3). Total cost of the mission is estimated at 16.4 billion yen (roughly $150 million U.S.)

Mission Profile

Hayabusa 2 launched on 3 December 2014 at 04:22:04 UT (13:22:04 local Japanese Time) from the Tanegashima Space Center on an H2A rocket. It will use an Electric Delta-V Earth Gravity Assist technique to reach the asteroid, flying by Earth on 3 December 2015 with a closest approach at 10:07 UT, and arriving at asteroid Ryugu (1999 JU3) in June 2018. It will stay at the asteroid and conduct science operations for about a year and a half. The impact operation and sampling is scheduled for early 2019 with departure from the asteroid in December 2019 and return to Earth in December 2020.

While at the asteroid Hayabusa 2 will make three sampling runs, the first two from the unaltered surface and the third from inside the crater formed by the SCI. A typical sampling run will start with the spacecraft commanded to move towards the selected area. At an altitude of 100 meters the craft will enter autonomous mode and shortly thereafter release a target marker to land in the desired area. At 30 meters the craft will align itself over the target and then slowly approach the surface and touch down. The 1 meter long sampling horn will cover the target area, and a tantalum projectile will be fired into the surface, ejecting material back up the horn through a 14 cm wide opening into one of three storage containers, which will then be sealed. The bottom of the horn also has protrusions and a raised inner rim to trap samples of material during touchdown. The spacecraft will then move away from the surface and continue its scientific operations.

MASCOT (Mobile Asteroid Surface Scout)

The MASCOT lander is a 30 x 30 x 20 cm box with a mass of 10 kg. It carries an IR Radiometer, magnetometer, camera, and MicroOmega spectrometer. It has no landing mechanism but will be dropped on to the surface from low altitude. It has a rotatable mass which will allow it to reorient itself after landing and also to "hop" to a new location on the asteroid's surface. MASCOT is powered by batteries which have a planned lifetime of about 12 hours.

SCI and DCAM3

The Small Carry-on Impactor (SCI) is a small cylindrically shaped penetrator which will be deployed from the Hayabusa 2 spacecraft and launched by means of an explosive charge towards the asteroid. Before the SCI is launched, Hayabusa 2 will move to the opposite side of the asteroid so as not to be affected by the explosion, shrapnel, or resulting ejecta. The Deployable Camera (DCAM3) will also be dropped off before detonation in order to return images of the impact. The impactor has a diameter of 30 cm, is 30 cm high, and has a total mass of 15 kg, including the electronics, housing, and detonator. The projectile itself is a 2.5 kg copper liner backed by a 4.5 kg conical shape charge of plasticized HMX explosive. The SCI will be maneuvered into position and aimed at the target point on the asteroid before release. (SCI has no attitude and position control.) The explosive will be detonated, deforming the copper liner into an impactor shape and driving it into the asteroid at 2 km/s.

Asteroid 1999 JU3

Asteroid Ryugu (originally 1999 JU3) is a Near Earth Asteroid with a semi-major axis of 1.19 AU and an orbital eccentricity of 0.19, which puts its perihelion near Earth's orbit and its aphelion near Mars'. The asteroid is roughly spherical (axis ratio approximately 1.3 : 1.1 : 1.0) with an effective diameter of 875 meters and a rotation period of 7.6 hours. It is a C-Type (carbonaceous) asteroid, expected to be relatively rich in organic compounds.

Alternate Names

  • 40319

Facts in Brief

Launch Date: 2014-12-03
Launch Vehicle: H-2A
Launch Site: Tanegashima, Japan
Mass: 600.0 kg

Funding Agency

  • Japan Aerospace Exploration Agency (Japan)

Discipline

  • Planetary Science

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David R. Williams.

 
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