Japan has successfully launched the second sample return mission to an asteroid, with a JAXA H-IIA rocket carrying the Hayabusa 2 probe into orbit on the first leg of its journey to the asteroid (162173) 1999 JU3. Launch occurred on schedule at 04:22 UTC on Wednesday from Pad 1 of the Yoshinobu Launch Complex at JAXA’s Tanegashima Space Centre.
Hayabusa 2 Mission:
Based on the original Hayabusa spacecraft, which was launched in May 2003 on a mission to return samples from the asteroid (25143) Itokawa, Hayabusa 2 is a small, 590-kilogram (1,300 lb) spacecraft which was built by NEC Corporation.
The spacecraft builds on JAXA’s experiences with Hayabusa, and its design aims to correct many of the flaws which affected its predecessor’s mission.
Deployed by an M-V rocket in 2003, Hayabusa, which was also known as MUSES-C, suffered damage from a solar flare a few months after launch, reducing its ability to generate electricity and thereby impacting the power available for its ion propulsion system.
Two years into its mission, and a few months before its arrival at the asteroid Itokawa, one of the spacecraft’s reaction wheels failed. On 12 September 2005, however, Hayabusa took up station 20 kilometres (12 miles, 11 nautical miles) from Itokawa. A second reaction wheel failed a month after its arrival.
On 12 November 2005, Hayabusa approached to within 55 metres of the asteroid in order to deploy a lander, Minerva. The lander was released later than had been planned, after Hayabusa had begun to back away from the surface, and as a result Minerva drifted off into space. A week later JAXA attempted to land Hayabusa itself on the asteroid to collect a surface sample before again backing away.
Although the attempt did result in Hayabusa reaching the surface and collecting a small amount of matter from Itokawa, the sampling system failed to function. Two days after the initial landing a second attempt was made but again the sampler failed to operate.
Around the time of the second landing Hayabusa’s reaction control system developed a problem, affecting JAXA’s ability to control its attitude. Attempts to manoeuvre the probe were taking it out of solar alignment and resulting in a loss of power. Attempts to recover control of the spacecraft continued until early December, when all communication was lost.
JAXA reestablished contact with Hayabusa in late January 2006, however by the time it was back under control the spacecraft had missed its departure window for returning to Earth, necessitating that it remain in the proximity of Itokawa until April 2007.
Despite further problems with its ion engines during the return trip to Earth, Hayabusa reached Earth on 13 June 2010. Its return capsule, which separated from the main spacecraft three hours before reentry, was successfully recovered on Australia’s Woomera Test Range. Hayabusa itself was destroyed during reentry.
Similar in design to Hayabusa, the Hayabusa 2 spacecraft is propelled by four ion thrusters with power coming from twin solar arrays. Two high-gain antennae mounted atop the spacecraft, operating in the Ku and X bands, will be used to communicate with Earth.
Designed for a six-year mission, Hayabusa 2 will arrive at the asteroid in 2018 and conduct eighteen months of research before returning to Earth in 2020.
The sampling system aboard Hayabusa 2, SMP, is based on that flown on Hayabusa. Small projectiles are fired at the surface of the asteroid to eject matter, which enters the collector and is stored in one of three chambers. These samples will be transferred to the spacecraft’s reentry capsule for return to Earth.
To aid its landing on the asteroid, Hayabusa 2 is carrying five target markers, which JAXA describe as being “like beanbags”, that can be ejected towards the surface. These are designed so as not to bounce upon impact, providing fixed reference points for landing attempts.
Hayabusa 2 is also carrying four small deployable landers and an impactor. The Mobile Asteroid Surface Scout, or MASCOT, is a German-built probe which will land on the asteroid to undertake measurements of the surface conditions using an infrared spectrometer, a magnetometer, a radiometer and a camera.
The lander is capable of making a single liftoff from the asteroid surface in order to reposition itself to a second site for additional research.
Minerva 2 consists of three additional landers in place of the one carried on the first Hayabusa mission. These are small, manoeuvrable, craft capable of making multiple short ‘hops’ across the surface.
Hayabusa 2 is also carrying the Small Carry-on Impactor (SCI), which will be deployed above the surface along with the DCAM-3 subsatellite intended to observe its impact.
SCI consists of a 2.5 kilogram (5.5 lb) projectile which will be fired into the asteroid surface by the detonation of a 4.5 kilogram (10 lb) HMX shaped charge. After Hayabusa 2 is repositioned on the other side of the asteroid, the HMX will be detonated propelling the copper into the asteroid at high velocity.
The DCAM spacecraft which will observe the impact is derived from two previous DCAM vehicles used to verify solar sail deployment during the IKAROS mission.
The asteroid which Hayabusa 2 will visit is currently designated (162173) 1999 JU3, a provisional designation which will likely be replaced with a more permanent name by the time of the probe’s arrival. A C-type, or carbon rich, asteroid, it orbits between Venus and Mars, crossing the orbit of Earth and taking 1.3 years to complete a revolution.
Discovered in May 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) project, it has been classified as part of the Apollo group of asteroids. 1999 JU3 measures about a kilometre (1,094 yards) across.
Hayabusa 2 shared its ride into orbit with three small satellites. Proximate Object Close Flyby with Optical Navigation, or PROCYON, is a technology demonstration mission with which JAXA intend to perform flybys of three asteroids.
The primary mission objectives of the 59-kilogram (130 lb) spacecraft are to evaluate the performance of such a small spacecraft on an exploration mission and to use delta-differential ranging and optical navigation to achieve close flybys of its targets.
Kagoshima University’s Shin’en-2 will also be used for technology demonstration. A successor to the Shin’en spacecraft which launched with Akatsuki in 2010 but failed shortly after launch, Shin’en-2 is intended for use in evaluating long-range communications.
The final payload launched is the Tama Art University’s Deep Space Amateur Troubadour’s Challenge or DESPATCH spacecraft. A sculpture equipped with an omnidirectional beacon for the benefit amateur radio enthusiasts, DESPATCH is the second spacecraft to launch as part of the university’s ARTSAT project, following on from the INVADER satellite deployed in May.
Mitsubishi Heavy Industries H-IIA rocket was used to deploy Hayabusa 2. A two-stage rocket, the H-IIA flew in its 202 configuration, with a pair of SRB-A3 solid rocket motors augmenting its first stage at liftoff.
The rocket’s first stage is powered by an LE-7A engine, while the second stage is powered by an LE-5B. Both stages burn cryogenic propellant; liquid hydrogen oxidised by liquid oxygen.
First flown in August 2001, Wednesday’s launch marked the twenty-sixth flight of the H-IIA and the fifteenth use of the 202 configuration. In its previous launches the H-IIA has experienced only one launch failure, occurring during the sixth launch in November 2003 when a solid rocket motor failed to separate from the vehicle. Two reconnaissance satellites were lost in the failure.
The H-IIA flies from Pad 1 of the Yoshinobu Launch Complex at JAXA’s Tanegashima Space Centre. Built in the 1990s for the H-II, Yoshinobu consists of two launch pads. Although it was built for the H-IIA, Pad 2 is used to launch the larger H-IIB. The Hayabusa launch is the thirty-seventh from Yoshinobu across both pads, and the thirty-third from Pad 1.
Wednesday’s launch began with the ignition of the H-IIA’s LE-7A engine, followed by the two SRB-A3 solids. The solid rocket motors burned for 99 seconds, providing additional thrust during the early stages of flight.
Nine seconds after they burned out, the solids were jettisoned from the first stage in order to reduce mass. Around four minutes and ten seconds after launch, at an altitude of around 137 kilometres (85.1 miles, 74.0 nautical miles), the payload fairing separated from around Hayabusa 2 at the nose of the rocket.
The first stage engine burned for around six minutes and thirty six seconds before exhausting its supply of propellant and shutting down. The spent first stage separated from the vehicle eight seconds later, with second stage ignition occurred six seconds after staging. This was the first of two burns for the second stage’s LE-5B, with a duration of four minutes and twenty eight seconds.
The second stage’s first burn placed Hayabusa 2 into a low Earth parking orbit. It was followed by an 88-minute, five-second coast phase before beginning a four-minute, one-second burn to accelerate the vehicle and its payloads to escape velocity. Three minutes and fifty one seconds after the burn was complete, Hayabusa 2 separated from the H-IIA to begin its mission.
Shin’en-2 separated six minutes and forty seconds after Hayabusa, with DESPATCH following after another four minutes and ten seconds. The final spacecraft, PROCYON, was deployed after a further four minutes and ten seconds, at two hours, two minutes and fifteen seconds mission elapsed time.
Wednesday’s launch was the seventy-eighth of 2014. Japan’s fourth and final launch of the year, it followed the successful deployments of the GPM Core Observatory, Daichi 2 and Himawari 8 satellites by H-IIA missions in February, May and October.
Japan’s next launch is expected to occur in the early months of 2015, with two H-IIA missions planned to boost Japan’s fleet of reconnaissance satellites.
Two further H-IIA missions are planned towards the end of the year, with the ASTRO-H observatory scheduled to ride an H-IIA to orbit in November while an H-IIA 204 will conduct Japan’s first commercial launch when it carries Canada’s Telstar 12V communications satellite.
Japan will also conduct an H-IIB launch in 2015, with the Kounotori 5 resupply mission to the International Space Station currently slated for liftoff in August.
(Images via JAXA)