* Astronomy

Blobrana · L

RE: HAYABUSA (MUSES-C) mission

Blobrana · L

A small correction manoeuvre will be made tonight.
If the mission control confirms the results are correct, Hayabusa will attempt a second touchdown.

Blobrana · L

Distance from Earth : 288,250,500 km
Distance from Itokawa : 20 km

Blobrana · L

There was no damage found to have occurred to the probe, or the sensors, after Sunday's touchdown.

The Hayabusa space probe is to make another attempt at landing on the surface of an asteroid on Friday at around 07:00 GMT.
Today, the spacecraft was at a distance of about 30km to 40km from Itokawa.

Blobrana · L

As soon as the front end of the cone on Hayabusa touched the surface Sunday, a tantulum pellet should have fired and the device should have captured the resultant ejecta.
This operation was aborted by the onboard computer.

"The end is like a cone and the central part is a cylinder. They fire a pellet down the centre of the scoop into the surface at 300 meters per second, causing ejecta to explode off the surface, and as the ejecta comes up, it funnels into the chamber" - Donald K. Yeomans, senior research scientist at the Jet Propulsion Laboratory (JPL) and the U.S. project scientist for the mission.

The collecting chamber may however have captured kicked up dust from the bumpy landing.
Two more chambers are available for another try this weekend.

Blobrana · L

Before landing, Hayabusa dropped a small object as a touchdown target from 130 feet above the asteroid and then descended to within 56 feet of the surface, at which point ground control lost contact with the probe for about three hours. But after analysing data later sent by the probe, the agency confirmed that it landed on the asteroid within about 100 feet of the landing target.

"I think we did a great job" - Yasunori Matogawa, JAXA Associate Executive Director.

Hayabusa detected an obstacle just below the altitude 17m, it then changed the orientation of the spacecraft towards the surface of Itokawa. At that point the high gain antenna moved away from Earth and the real time communication was lost.

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Credit JAXA

Software onboard Hayabusa tried to go into the emergency take off but the orientation of the spacecraft was too steep (to the surface) so it did not take off. It continued the free fall descent and bounded twice on the surface, according to the LRF data and the attitude data.

-- Edited by Blobrana at 21:01, 2005-11-23

Blobrana · L

JAXA/ISAS is still downloading the data. They might find more news on the rest of the data. No significant damage to the spacecraft has been confirmed, but some heater sensors need checking.

Some sand should come up at the impact of the touch down. Part of them should have reached to the sampler capsule. The capsule was programmed to be closed according to the sequence of the touch down, so it is still open now. Scientists insist on closing the capsule, so they will send the closing command in the next communication window tomorrow. There are several capsules on board for two scheduled touch down operations.

Image from the Sunday touchdown

Currently Hayabusa is approaching to Itokawa at 4 km per hour. As it closes up, it slows down for delicate positioning. It depends on whether they can bring it back to the starting position, and also on the stamina of the operation team members, to have the second attempt on the 25th.

source

Blobrana · L

According to the LRF data, the touch down occurred around 6:10. There was a bounce, and another touch down occurred around 6:30. the spacecraft settled after another smaller bounce.

It stayed on the surface for 30 minutes.
The overheating that the mission control teams registered was the probe actually being heated up by thermal radiation from the surface of Itokawa.
A command from Earth at 6:58, lifted the probe, that then entered into the safe mode.

The spacecraft unfortunately came to rest at an angle, with an edge of the body or A solar panel wing resting on the surface.

Because the obstacle sensor had been triggered, the sampler horn was not engaged, so the impactor was not deployed.
The event happened during the switch over from NASA Goldstone station to Usuda station, so they could not confirm the landing from the Doppler data.

Blobrana · L

The Japan Aerospace Exploration Agency (JAXA) has released a statement saying that the Hayabusa space probe successfully touched down on the asteroid last Sunday.
The spacecraft however failed to drop the sampling equipment to collect samples.

The space agency said that the spacecraft managed to touch down on Itokawa asteroid for about 30 minutes.
This is the first landing by a Japanese space vehicle on an astronomic object.

JAXA will decide Thursday whether to make a second attempt to land Hayabusa.
According to the agency, the probe has not suffered any major damage, but some of its censors still need to be checked.

Blobrana · L

According to a report issued by the Hayabusa Joint Science Team, after analysing the data returned by the spacecraft, the team found that the spacecraft had managed to get to within about 10 meters of the surface, before it autonomously went into safe mode and cruised above the surface for 30 minutes, until mission control sent a signal to abort the landing.

Hayabusa did not succeed in retrieving a sample, but managed to release the target marker towards Itokawa, when the spacecraft descended to an altitude of about 40 meters.

At 5:46 a.m. (JST), November 20th, JAXA received the signal that Hayabusa had carried out its task successfully. This particular target marker carried an aluminium sheet bearing 880,000 signatures from people around the world – and delivered it to the surface.
Moving at a velocity of 10 centimetres/second, the target marker landed about six and a half minutes after it left Hayabusa, settling down just as planned in the flat region that the team dubbed Muses Sea.

Hayabusa continued to autonomously descend toward the surface and should have changed its attitude control to terrain alignment autonomous control using Laser Range Finder.
Its autonomous navigation relies on the Optical Navigation Camera and Light Detection and Ranging (ONC/LD&R) instrument, which measures the distance to and the shapes of the asteroid surface.
If the mission had gone as planned, the spacecraft would have continued on to a "soft" landing, touching down on the surface just long enough for its sample collector to reach out and seize just one gram of top soil, and then return to its home orbit around 7 kilometres out.

However, according to the Doppler signals received at the ground station, when Hayabusa got to below 17 meters, it stopped firing its engines and started into a freefall descent to the surface.

"We were watching it via Doppler. But no touchdown occurred for surprisingly 30 minutes, during which the descent continued at very slow speed of about 2 centimetres per second. We estimate Hayabusa drifted at very low altitude along the surface. Therefore, Hayabusa did not touch down the surface, but reached approximately below 10 meters” - Science Team report.

According to temperature sensors aboard the spacecraft, Hayabusa hovered above the surface long enough for part of it at least to heat up to around 100 degrees Celsius. Concerned about the temperature, the team sent up a command to Hayabusa to move quickly away from that position.

Signals take around 17 minutes to get from Earth to Hayabusa.

Hayabusa then ascended to about 100 kilometres from the asteroid.

"We directed a command to Hayabusa to make an abort, since the sub-spacecraft point might have shifted so much from the intended area" - Science Team report.

The team is not yet exactly sure why Hayabusa fell into safe mode, but they believe it is because of an "attitude anomaly" that occurred close to the altitude of about 10 meters or so; or it may have been because Hayabusa failed to keep a correct attitude just before touchdown and autonomously decided to put itself into safe mode in order to save fuel.

Hayabusa may try another landing attempt next Friday, November 25.

Information from press conference at 4 p.m. JST , Sunday, held at the ISAS headquarters in Sagamihara City, Kanagawa Prefecture.