This was posted in the Dec 1st Mars Express Status report
http://sci.esa.int/science-e/www/object/in...fobjectid=36181



Has anyone heard if this decision has been reached yet?

guess huygens is booming right now

http://www.newscientist.com/article.ns?id=dn6974

It's now been officially announced -- late April or early May:
http://www.esa.int/export/esaCP/Pr_8_2005_p_EN.html

Not having heard anything more, I'm assuming that this is on target for next week. Fingers crossed.

Chris

Deployment is scheduled for May 2 according to Prof Neukum, PI for the High Resolution Stereo Camera on Mars Express in a recent audio interview on Planetary Radio - available here

Here is the ESA confirmation of the May 2 deployment date. The process will continue through May 12 as the three booms are deployed in sequence, with system checks between each. After that, there are three weeks of commissioning before scientific measurement actually begins.

I don't expect any data on this for a long time.

I do expect Big News when the time comes to releasing it.

Is there anywhere we can see simulated marsis images? I'd like to see how exactly the data is made into imagery......or is it...?

MARSIS homepage.

In the documentation section of the MARSIS homepage there is a quick look folder. Perhaps this is where they will bung the very preliminary data/results/analysis post deployment (there are no files in this folder at present)

E) OPERATION
E1) Planning
E2) Commanding
E3) Monitoring
E4) Quick look


F) PROCESSING
F1) Data Archiving
F2) Calibration
F3) Ground segment
F4) Science Processing


BBC coverage of MARSIS.

Article says deployment of the first boom is now scheduled for the 4th of May. As for Big News about the deployment:

"We don't want to go blowing our trumpets until we've deployed at least the first two booms," said a spokesman for the agency

My guess is that ESA would like to keep a failure to deploy under the radar of the press (pun only slightly intended). Also the journos are gonna be expecting pretty pictures and they are gonna take a while to produce and only be exciting/deciferable to us remote sensing freaks.

As an non-RSF, I'm not so intersested in the images as the bottom line. What do the images tell us? Are there signs of layers of water beneath the surface and can it be determined if it is liquid or frozen. The artist's rendering that came with the press release, showing an underground cave filled with water was very provocative -- perhaps too much so. If a similar situation were to be indicated by the data that would be big news indeed!

Stupid question...what is an RSF?

Remote Sensing Freak. I just made it up. The acronym, not the phrase.

Any deployment news?

I doubt we'll hear anything for a while. From
http://www.newscientist.com/article.ns?id=dn7334

"But ESA officials say determining the success of the deployment can be tricky, so they may wait until all three booms appear to be operating properly before making any announcements about the experiment. "We will not make the mistake of touting the trumpets when we are not sure," Jansen told New Scientist."


Chris

First deployment successful!

Europe's Mars Express spacecraft has deployed the first of three booms that comprise its Marsis radar, which is to look for water within the Red Planet.
At 1530 BST on Wednesday, a command was sent to release the boom, which forms one half of Marsis' primary antenna.

The primary antenna's second boom is now due to be deployed on Sunday.

Fears that one or more of the antenna components could swing back and hit the spacecraft led deployment of the booms to be delayed for more than a year.

Spacecraft telemetry suggests the boom deployed successfully.






http://news.bbc.co.uk/1/hi/sci/tech/4516535.stm

Cool!

BTW, does anyone know of any animations showing how the booms unfold?

Chris

Think of a tape measure - rolled fully out

Then get a box the shape of a laptop PC

Fold the tape measure into the box, put some tape of the end.

Now take the box into space, and rip the tape off

http://www.st.northropgrumman.com/astro-ae...marsispaper.pdf

Doug

Great paper. Thanks a lot for that link, Doug.

Chris

Dang. This won't be very helpful, but - I do know there is a brief video clip of a test deployment in a pool of water (to simulate zero-g). BBC maybe? I don't remember where I saw it. It doesn't show the whole deployment, though - if you're interested in the bit at the end where the antenna waves around and possibly hits the spacecraft, I haven't seen anything like that.

There was a small anomaly in the first boom deployment, causing a delay for the second boom deployment.

http://www.esa.int/esaCP/SEMQGXY5D8E_index_0.html

Does anyone have any idea what effects this locking failure
could have on the the boom functionality? If any..

Potentially disastrous -- there's a good chance they'll have to abandon the experiment completely as a result of this:
http://www.nature.com/news/2005/050509/full/050509-1.html

Once again, moving parts prove to be the bane of space missions. One would
really think that engineers could get these things to work better.

What mechanism was used for the booms on Cassini - they're what, 10m each?

I dont think booms this size have been deployed on a spacecraft that wasnt spin-stable ( Ulysses for example - just roll out a very long wire of 75m length)

Worryingly, MRO's Sharad is considered MARSIS heritage - it looks to be a smaller antenna (cant find figures (edit - might have done - 7m perhaps ) ) but one has to ask if it's a similar type of deployment mechanism?

Doug

Oh, believe me, MUCH longer booms have been successfully deployed on a non-spin stabilized craft -- and for a very long time. The two Radio Astronomy Explorers (one orbiting Earth in 1968, the other orbiting the Moon in 1973) deployed 6 booms up to 750 feet long with no trouble at all, using the time-honored technique of flat metal strips whose edges curled up into a rigid tube as soon as they came off their storage drums. (Viking's surface sampling arm used the same technique for repeated extensions and retractions, in Martian gravity). No doubt there have been a number of other such deployments longer than the MARSIS antennas, although I can't name any off the top of my head. In short, MARSIS' designers seriously screwed the pooch -- although it's still possible that the situation is retrievable.

From what I understood the boom was more or less a spring stuck in a box that
returned to its 'natural' state when the box was opened.

From the little I know of it all, I thought the whole design relied on the potential energy stored in the boom in its stowed position to extend itself.

As such, what mechanisms might be available to allow them to manipulate the boom in order to free the hinge?

jG

Thanks for filling in the gaps Bruce. Same technique was used for the Pathfinder egress aids iirc.

Question is then - why the hell the obscure folded affair for MEX JPL has big input into this thing - ( U.S. (Jet Propulsion Laboratory), will be responsible for the system design with participation of Italy (Alenia Aerospazio). - www.marsis.com ) I'm amazed they screwed up here.

If it's kinked - I guess they could try spinning the spacecraft two and fro in an attempt to 'un' kink it

Doug

It turns out that the antenna wa designed and built entirely by good old Uncle Sam, and specifically by TRW:

http://www.st.northropgrumman.com/astro-ae...ocs/pdfs/marsis
paper.pdf

What this paper drives firmly home is the danger of depending mostly on
mathematical simulations to try to describe the behavior of real-world
substances. Since that problem has bedeviled engineers for most of the past
century (or two), one would think TRW would have recognized the risk level
of their gamble. I suspect from the description of the "hinges" (actually
just points along the fiberglass tubes where a slot-shaped cutout in one
side of the tube allows the tube to be folded at that point) that one of the
tubes simply cracked at that point, either before or during unfolding.

"The tube elements were tested to demonstrate... hinge actuation
reliability. Multiple operations of sample hinges were made under all
temperature extremes including in liquid nitrogen. The tests did demonstrate
some problems with the initial cutout configuration. Design modifications
were made, arriving at the shape shown in the figures...

"Conclusions: This program required new methods to be developed to validate
the design and to assure performance of flight hardware. A combination of [computer] analysis and [limited] component test was utilized to accomplish
this goal."

Put not your trust entirely in numbers. Particularly to simulate mechanical
operations, and particularly in space.

I assume the demands of the instrument dictated that it be a fibreglass tube with, one pressumes, wire running down it - instead of just a metal deployment device like a metal tape-measure

doug

Good news from ESA website:

http://www.esa.int/esaCP/SEMY3R5TI8E_index_0.html

First MARSIS boom successfully deployed


11 May 2005
Thanks to a manoeuvre performed on 10 May 2005 at 20:20 CET, ESA flight controllers have successfully completed the deployment of the first boom of the MARSIS radar on board ESA's Mars Express spacecraft.

After the start of the deployment of the first 20-metre boom on 4 May, analysis by flight controllers at ESA’s European Space Operations Centre, Darmstadt, Germany, had shown that although 12 out the 13 boom segments were in place, one of the outermost segments, possibly No. 10, had deployed but was not locked into position.
Deployment of the second (20 m) and third (7 m) booms was suspended pending a full analysis and assessment of the situation.

As prolonged storage in the cold conditions of outer space could affect the fibreglass and Kevlar material of the boom, the mission team decided to ‘slew’ (or swing) the 680 kg spacecraft so that the Sun would heat the cold side of the boom. It was hoped that as the cold side expanded in the heat, it would force the unlocked segment into place.

After an hour, Mars Express was pointed back to Earth, and contact re-established at 04:50 CET on 11 May. A detailed analysis of the data received showed that all segments had successfully locked and Boom 1 was fully deployed.


The operations to deploy the remaining two booms could be resumed in a few weeks, after a thorough analysis and investigation of the Boom 1 deployment characteristics.

The Mars Express Sub-Surface Sounding Radar Altimeter (MARSIS) experiment is to map the Martian sub-surface structure to a depth of a few kilometres. The instrument's 40-metre long antenna booms will send low frequency radio waves towards the planet, which will be reflected from any surface they encounter.


MARSIS is one of the seven science experiments carried on board Mars Express, one of the most successful missions ever flown to the Red Planet. Mars Express was launched on 2 June 2003 and entered Mars orbit in December 2003.

Does anyone know how they are able to determine correct/incorrect deployment? They don't have cameras, so I can only see that they are relying upon some electrical property of the antenna.

Chris

Great news! Thanks for the update.

The Register » Odds and Sods » Science »
Another update:

Original URL: http://www.theregister.co.uk/2005/05/12/marsis_fixed/

Heat treatment straightens out MARSIS boom
By Lucy Sherriff (lucy.sherriff at theregister.co.uk)
Published Thursday 12th May 2005 11:05 GMT
Flight controllers on the Mars Express mission successfully deployed the troublesome first boom of the MARSIS experimen. All it needed was a little bit of heat.

When the first antenna began to open on 4 May, all but one of the 13 segments locked into position correctly. One section, probably the 10th, had unfolded, but was not locked in place. It was almost as though the boom had a crick in its neck after being folded up for so long en-route to, and in orbit around, Mars.

The mission engineers reasoned that since the cold of space can affect the Kevlar and fibre glass of the boom, they needed to heat the area in the hopes that it would expand the cold part, forcing the segment to lock out properly. So they swung the spacecraft around so that the cold side of the boom faced the distant sun. After an hour, the data suggested that the plan had worked, and the final piece had locked into place.

Mission controllers had postponed deployment of the second and third booms, until the problem with the first could be rectified. Mission scientists are still working on a thorough analysis of what exactly happened with boom one, but now that everything is in place, the rest of the unfurling should be resumed within the next few weeks.

The MARSIS experiment, full name Mars Express Sub-Surface Sounding Radar Altimeter experiment, is designed to map the Martian sub-surface structure to a depth of a few kilometres. It is one of seven scientific experiments on board the craft. ®

© Copyright 2005

According to this article ( http://www.newscientist.com/article.ns?id=dn7369 ):

"... they received telemetry from the gyros showing the action was a success ...".

This is looking like a sorry tale indeed. From the new Scientist article:



Chris

Apparently that last statement is the conclusion of the reporter himself, and I'm skeptical. Why not simply deploy the second antenna while it's still cold -- thus keeping its flexibility relatively limited and minimizing whiplash -- and THEN warm it up to straighten out any remaining kinks, exactly as they did with the first antenna?

"Jansed said, before the kink was ironed out" ....... which in light of it's now successful deployment makes most of that part of the article obselete.

I see some irony in that. They are afraid of swing, right? And they wait over year and now equipment is "frozened" a little.
Maybe this latency in deploy of MARSIS was exactly the right thing. MARSIS deployment can't swing back because of stiffened boom. In that way one dangerous thing neutralise other dangerous thing.

Well, one can argue that takes a little too long time - after all one segment can't locked properly. Hope that other booms will deploy nicely.

I don't see where it says it won't work if all the sections are not fully locked.

The deployment will take much longer, according to some news that I just received. We might see a press release in the coming days...

now what's gone wrong?

The way it works is to have an antenna length that matches the wavelength (or a fraction of it, 1/2, 1/4 ) of the signal being used.

I'm not a radio scientist, but the size of the antenna is important and is designed specifically for the signal being used. I would guess that not having the full (and thus exact length) antenna deployed would greatly compromise the science return, if not rule out operation all together.

Doug

I'm also not a radio expert, but I suspect that if the antennae are wrongly sized and you blast a signal out regardless you could also damage the transmitter, and by implication, much else aboard the spacecraft - so if it ain't 100% right then I doubt it'll happen at all, unless there's some science to be had in a passive mode...

Actually, they *do* - remember the Beagle 2 deployment shot?

But that doesnt point in the direction of Marsis

Doug

It *might* if Marsis was bent!

Ooh, I hope not...

Judging by the recent pictures of Mars Express from MGS it may be possible to image MARSIS that way.

sharads antenna - which is similar to Marsis, but a lot shorter, can be seen in lots of pics of MRO

http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=25873
http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=25871
http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=25869

Doug

So any new info on deployment?

Up to June 4th, there was no decision to deploy the 2nd boom. I will let you know if anything new comes up.