What's Up With Hayabusa? (fka Muses-c) Options

[Guest_Myran_*]

My first thought was that the target had failed to reach the surface, either released hanging in space or even bounced off the surface. And the Hayabusa spacecraft had followed but gotten into a conflict when the laser didnt report any surface.
But from the last translations it seems that it really did reach the surface.

Translation: So we didn't know Hayabusa was rotating. It was not before we received the signal from medium gain antenna that we realized it is rotating.

I interpret this as Hayabusa have gotten in physical contact with the asteroid and gotten a push.

[Rakhir]

A little summary of what I understood from the google translation of the 16:00 update at smatsu.air-nifty :

Hayabusa succeeded in keeping track of the target marker but stopped at 10m. Then, it kept hovering close to the surface for 30 min.
Therefore, the sampling didn't happened even if this point is still to be confirmed.
By the time, the temperature rose because of the radiation from the surface.
Hayabusa finally went into safe mode.

They have now to check for any damage on the spacecraft.

It is not clear for me if they already regain the 3-axis attitude control.

Does the following mean that Hayabusa is now at 100 km from Itokawa ?
"In addition, because you seceded rather to high speed, somehow it is quick the ぶ, the pattern which to the 100km vicinity leaves from the I To matte. As for resetting on the basis of this the pattern which fit days is required".

Rakhir

[Rakhir]

From Project manager Kawaguchi.
Next scheduled steps are :
1 - Test the probe to check for any damage
2 - If everything is OK, try a second sampling.

[hugh]

Does the following mean that Hayabusa is now at 100 km from Itokawa ?
"In addition, because you seceded rather to high speed, somehow it is quick the ぶ, the pattern which to the 100km vicinity leaves from the I To matte. As for resetting on the basis of this the pattern which fit days is required". 

Rakhir

It translates to me as "Because we receded at fairly high speed, Hayabusa moved nearly 100 km away from Itokawa. It will take some time to return to our former position" My Japanese is far from fluent, even after living here several years, but
for what its worth some of the other details read to me as:

During descent the laser range finder worked normally, and Hayabusa
hovered at 55m altitude.
At 17m the signal from the high gain antenna was interrupted.
From this point on we only have Doppler data.
We think Hayabusa drifted horizontally and orbited, staying at about 10m for 30 minutes.
It appears the craft did not touch down.
Staying this close to Itokawa’s surface is dangerous as radiation causes a temperature rise in the craft. Therefore the craft was commanded to rise at 7 oclock.
At this point the craft went into safe mode. We do not know yet why this happened.
We were able to arrest the crafts spin, but 3-axis stabilization was not established.

[hugh]

Hayabusa drifted horizontally and orbited

whoops, that "orbited" should probably be "spun"-orbiting at 10m altitude sounds unhealthy...

There may be an excellent translation of the press conference at
5thstar's site before long.

[Guest_Myran_*]

Thank you hugh, that is how I had understood it also, that Hayabusa had reached the surface.
Then that the signal from the antenna was lost was small consequence in itself if it only was due to occulation - it still should have went on sampling automatically and then ascended. Now it didnt suggest there was a program error or conflict.
Important question, but one that im far from certain that anyone can answer: Is there a way to tell if the sampler is in working condition?
And yes btw saying radiation might get most to thing of something else than infrared radiation which I think you intended to say.

[hugh]

something else than infrared radiation which I think you intended to say.

Yes, 5thstar translates "radiation" there as "sun light reflection from the surface"
which seems more correct.

His translation of much of the 4 PM Kawaguchi press briefing is up now- it must have been a marathon effort to translate-some quotes:


Kawaguchi: "The spacecraft has a software which will be triggered by the distortion of the sampler horn. We know this has not been triggered based on the telemetry received at Usuda.However the spacecraft went into ascent mode autonomously, so there (may) have been some turbulence such as some part of the spacecraft touched the surface of Itokawa. We don't know precisely at this point."


NHK: "The software was not triggered means the impacter was not ejected. Are you really sure the spacecraft did not touch down?"
Kawaguchi: "You are right. Even if some portion of the spacecraft touched the surface of Itokawa, I do not want to declare it as a 'touch down'."


Gekkan Tenmon: "What about the remaining fuel?"
Kawaguchi: "We consumed fair amount. It is one of our concerns for the future operations. But we would like to try one more chance."
Jiji: "Would it be on time for the descent on November 25?"
Kawaguchi: "If we are to try again on the 25th, we need to hurry. There are so many things we need to consider. Also we can try the touch down operation only when the NASA DSN backup is available. There are not so many chances. We think we need to exploit the chances. But we also need to think again if there are damages in the spacecraft."
NHK: "The sensor for obstacles, which would trigger the abort, was not triggered?"
Kawaguchi: "No, it didn't."

[Guest_BruceMoomaw_*]

That is certainly a reference to "infrared radiation" -- Itokawa, being normal S-type asteroid rock, certainly is not unusually radioactive. That is, they're talking about IR radiation being radiated (and reflected) off the asteroid's surface onto the craft, in addition to its direct exposure to sunlight.

[Rakhir]

Also from 5thstar press briefing translation :
They are thinking about changing the criteria during the next attempt, for a more risky descent profile.
They could even plan a downward acceleration to reach the surface.

Indeed, it is the last chance to return a sample back to earth.

And about the fuel consumption :
"There is a method of extremely low fuel consumption but it depends on the conditions of Hayabusa and the maneuver of returning to Earth. Whether it can return to Earth depends on how we choose the safety factors. We need to evaluate.
It is not whether we can bring Hayabusa back to Earth or not. It is how we restrict our fuel consumption.
I myself feel it is very critical at this point."

[alan]

Unknown: "What was the impact of the reaction wheels?"
Kawaguchi: "We originally planned the last minutes descent without the attitude thrusters. Because of the malfunction of the reaction wheels, the spacecraft had to go through the small turbulence due to the thrusters. It affected today's event in some way. Pending on the analysis of today's data, we are even thinking to thrust the spacecraft downwards onto Itokawa."

Some speculation: The jets from the attitude control thrusters reflected off the surface onto the solar panels slowing the descent. Next time they are considering thrusting downward to overcome this.

[ElkGroveDan]

Some speculation: The jets from the attitude control thrusters reflected off the surface onto the solar panels slowing the descent. Next time they are considering thrusting downward to overcome this.

I like that explanation.

Additionally I suspect the unexpected hovering and pause may have triggered a state of confusion in the software -- especially if this condition had never been anticipated. They need to walk through their fault tree step by step where it is likely they will discover a dead-end that triggered the Safe Mode.

[RNeuhaus]

Besides, I am thinking that the shadow from the spacecraft Hayabusa when it was approaching enough to surface, perhaps in few meters, might have caused confusion to the software interface with the Light Detection and Ranging (LIDAR) which is sensible to the light in order to measure the distance.

The closer is Hayabusa to the surface, in front there will be a shadow surface...since the Sun is behind of Hayabusa and it is approaching to Itokawa in the perpendicular line from the Sun to Itokawa and also in almost the same line to Earth where its High Gain Antena is on the top pointing to the Sun and Earth at the same line.

Rodolfo

[Rakhir]

Besides, I am thinking that the shadow from the spacecraft Hayabusa when it was approaching enough to surface, perhaps in few meters,  might have caused confusion to the software interface with the Light Detection and Ranging (LIDAR) which is sensible to the light in order to measure the distance.

The closer is Hayabusa to the surface, in front there will be a shadow surface...since the Sun is behind of Hayabusa and it is approaching to Itokawa in the perpendicular line from the Sun to Itokawa and also in almost the same line to Earth where its High Gain Antena is on the top pointing to the Sun and Earth at the same line.

Rodolfo

From an altitude of 35m, the surface detection was switched from LIDAR to the Laser Range Finder (LRF).
So I don't think the shadow of the spacecraft is the cause of the glitch.

[centsworth_II]

I am thinking that the shadow from the spacecraft... might have caused confusion...

Perhaps the reflective target is meant to avoid this, with Hayabusa using its reflection rather than that of the surface beneath it for guidence.

That brings up the question. Is there another target for use during the next descent? If not, what differences are there in how Hayabusa handles a decent without as opposed to with a target? I doubt it could retarget the reflector already on the surface, but who knows?

edit: Ah! I see they do have another target on board and that at the end of the decent Hayabusa switched from radar to laser for guidence.

[Rakhir]

That brings up the question. Is there another target for use during the next descent?  If not, what differences are there in how Hayabusa handles a decent without as opposed to with a target?  I doubt it could retarget the refector already on the surface, but who knows?

There is one target marker left.