Actually, the discoloration was from acceptance testing hotfire on Earth. The thrusters are fired in a mostly evacuated test chamber, but it still has residual atmosphere, thus the Inconel chambers oxidize when they get hot. That is pretty much how they looked when they launched (since there is little or no O2 in the atmosphere of Mars).

Thanks propguy, I was wondering about that.

The grapple has let go of SEIS.

Into the wild

The arm is moving away from SEIS... (animated GIF attached)
Click to view attachment

It is, and also inspecting the tether.

The first plumb bob on another planet if I'm not mistaken.

what is the white thing about halfway along the tether?

It's the tether field joint, that connects the part of the tether located inside the circular Tether Storage Box (TSB) to the part located outside the TSB (called octopus), with SEIS at the end. Before deployment, the field joint is attached with velcro to the TSB (see here : https://mars.nasa.gov/system/resources/deta...IA22952-web.jpg ). When deployment occurs, the white sock ensures that the robotic arm load is not applied to the connectors.

ForceOn1m^2=(airdensity*windspeed^2)/2*g

The highest atmospheric density on Mars is equal to the density found 35 km above the Earth's surface.
The strongest Martian storms top out at about 60 miles per hour
g=3.8 m/s2

Is 'g' for gravity - if so how does that enter into the force of the wind?

If you really mean planet, I guess you could argue the Telltale wind indicator on Phoenix counts.

But much closer to the spirit of plumb bob, if you allow 'planetary body', are the photometric calibration targets that dangled in front of the cameras on Luna 9 / 13. They're the little shield-like objects (arrowed) hanging from the tip of the antennas in my photo at the Lavotchkin Association from a few years ago.

And here is one of them on the Moon:

Click to view attachment

(Luna 13 did not have them)

Phil

I don't think it does. I think the appropriate equation is 0.5 * density * area * windspeed^2 https://www.engineeringtoolbox.com/wind-load-d_1775.html

Given the nature and shape of the tether the drag coefficient would influence the wind load. When the tether is laid out static friction would oppose movement so gravity does have an effect, particularly given the weight of the pronged metal plate attached to the lower part of the cable.

We haven't seen new raw images for a few days. I wonder, does the government shutdown have an effect on the release of images? Or on the daily operations of the lander? Some general information about the effects of the shutdown on NASA can be read here: Planetary Society A quote from the article:



InSight celebrated its first Christmas on Mars, so I assume not much was scheduled to happen during this week even without the shutdown.

Probably just collecting meteorological data during the break, though something like a sequence of change detection images might be possible as well.

Phil

Four pics came down from Sol30.

https://mars.nasa.gov/insight/multimedia/ra...mission=insight

Has anyone read about any summaries of the meteorological data from TWINS and the JPL pressure sensor being released to the public? I visited the Spanish site and it mentioned that they had supplied the hardware for TWINS, but there was no data set provided.

There may be some confusion between air density and air pressure here. The pressure on a unit of surface area depends on the weight of the column of air above it. In order to produce, say, 6 mbar of pressure at the surface of Mars, the column of air would need to have a greater mass, thus a greater density, than that needed to produce 6 mbar of pressure on Earth. Also because of the lower temperature, the air density must be greater to produce the same amount of pressure. Since the wind force depends on the air density, not the air pressure, it should be greater than we might expect based on the pressure.

"Four pics came down from Sol30."

Yes, and they show the seismometer tilting as it is levelled.

Phil

Well spotted Phil:
Tweaked colours and brightness in this simple GIF using a sol 26 and a sol 30 ICC frame.
Click to view attachment

I am hopeful that Jean-Yves Le Gall's twitter account will be a source of new Insight pictures over the next few weeks even if none are added to the JPL Raw Images page due to the shutdown. There seems to be no new pictures at the present time:

https://twitter.com/JY_LeGall

New pictures did come down.

As most of the tether seems to be suspended mid-air between the lander and the pin plate, as (in my lay view) it seems suboptimal as it would seem to preserve that potential energy throughout the rest of the mission as tension in the tether system (i had expectations of it to lay flat with an almost vertical drop from the spooling system), so I'm curious if SEIS is truly at the 'end of its rope' so to speak, or if there is additional length of tether that hasn't been let out and may be let out later on, as i'd think that tension would tend to transmit vibrations more than a slack system would. If its at 'the end of its rope', im assuming the intent was to place it as far away as possible from the lander's vibrations and that is much better news than reducing what in engineering terms may amount to no more than aesthetic concerns as there aren't any signifficant forces acting on a fully dampened system?

The tether is only partly deployed, presumably to provide a worst case characterisation of vibration. The tether will be completely fed out and on the ground for operation.

A stereo pair of IDC images are now available on the InSight Raw image server.
They show the grapple positioned just to the side of SEIS.
Maybe to update the digital elevation map after SEIS was levelled? Or possibly to cross check data from the instruments inclinometers after levelling?
Sol 32 images link
EDIT: A single sol 32 ICC image came down later, the arm was no longer adjacent to SEIS and I can see no obvious change to the tether or SEIS comparing it to the sol 30 ICC image

Hi,

I probably missed some information about SEIS deployment, but...enlight me please - how far from the spacecraft was it placed? 1 meter? Two? Thanks in adv for information.

Maciej

Some explanations on how they use the sundial to orientate SEIS by finding where North is +- 2°
https://www.seis-insight.eu/fr/actualites/4...e-nord-sur-mars

1.8m, about the max they could reach.

With the tether being three meters in length, and the SEIS placed at full-IDA reach, it seems the remaining 0.9 meters was intended for slack that will be carefully arranged later in the process.

For a great visual sense of sensor placement we have Phil Stooke's map thread

According to this release link

"The area where SEIS now rests is directly in front of the robotic arm (to ensure that the umbilical cord connecting the instrument to the undercarriage rests flat on the ground), and as far away as possible (1 , 65 meters) of the probe, so as to minimize disturbances. The speed with which the engineers and geologists chose this removal site is related to the leniency of the area where the probe landed on November 26th. With a very small slope (only 2 to 3 degrees of inclination) and a striking absence of pebbles, almost all of the terrain located south of the landing gear and within reach of the robotic arm was suitable for the deployment of the seismometer." (Google Translate)

Sol 35 images on the server (link), they show the grapple being placed at varying heights above the center of SEIS and the last image from ICC shows the arm removed from the scene.

If I had to guess.. they could have practising arm placements for accurate deployment of the wind and thermal shield (WTS) If correct we may get to see the WTS chain mail skirt soon Sun Dials and Chain Mail on Mars, some old school technology never gets old

Click to view attachment

Sol 37 images are on the server (Link).
ICC frames show us the SEIS tether has been released from its storage box and is now on the ground Here is a simple GIF of the before and after.

Click to view attachment

[quote name='PaulH51' post='243134' date='Jan 3 2019, 09:34 PM']Sol 37 images are on the server (Link).
ICC frames show us the SEIS tether has been released from its storage box and is now on the ground Here is a simple GIF of the before and after.



Very cool, more visible progress.

Wow.. until you mentioned it i thought it was just the skirt, so yes actual chain mail with a quite artfully designed platelet structure at that, to be fitted to our little seismometer battling dust devils on the planet of war, amazing!

I was quite surprised to read the following, as i'd interpreted Mars' winds to be ineffectual of much more than moving sand and dust around and perhaps rattling solar panels, but i guess with such good ground connection a passing dust devil could perhaps induce quite an impressive umbrella effect on the dome (now im wondering what the upper m/s limit of DD winds are):

I find that pressure is a more intuitive measure than windspeed - roughly speaking the dynamic pressure of the circumferential winds (i.e. rho * V^2, ignoring a factor of 2) is the same magnitude as the pressure drop in the center of the vortex. This is true for cyclostrophic balance in rotating wind systems in general, on Earth or Mars.

Like most things, there are lots of small ones and a few big ones - dust devil pressure drops seem to follow a power law, with a cumulative slope of about -2 or so. Pathfinder and Phoenix observed one or a few devils a day with drops of 0.5 Pascals, a 5 Pascal drop would be expected to occur around 100x less often, but is still reasonable to expect. A 50 Pascal drop (~10% of the total atmospheric pressure of 700 Pa or so, 7 mbar) isnt realistic

Now, if the windshield on InSight weighs 9kg, call that 35 Newtons on Mars. It's what, 0.5m across? So maybe 0.2 m2 in area. So its weight per unit area is 170 Pascals. A 5 Pascal drop, or even a 25 Pascal drop, isnt going to budge it.

(I made a rather hokey extrapolation of this sort in considering deaths by dust devil in this paper (open access), discusses weight per unit area of barn doors etc... https://link.springer.com/article/10.1007/s11214-016-0239-2 )
Terrestrial dust devils typically have a pressure drop of tens to a couple of hundred Pascals (say 0.5 to 2 mbar, or 0.1% of the total pressure. Hurricanes can have pressure drops of several tens of mbar, or thousands of Pascals)

Annotated and processed GIF that shows the release of the load shunt assembly on the SEIS cable service loop.
I used 2 images that were already roughly aligned and at similar LMST
I wondering if they will have to use the scoop to open the loop by tugging on the tether pinning mass?
Click to view attachment

Very nice!

I have been looking at distant features. Here are a few things which I think I have identified correctly. I am still thinking about some other things.

The distant ridge to the east is a wrinkle ridge 10 km east of the landing site.

Phil

Click to view attachment

You think there is an issue? I don't know what the change is supposed to be/do mechanically.

Bruce Banerdt told me there was a 50% chance they'd have to do that. I'm talking to him this afternoon and should have an update for you all tomorrowish.

Animating the IDC and ICC images taken before and after the load shunt assembly (LSA) was released shows the plates have moved, but still appear to be in contact, it looks to me that the plates have just rotated a little (clockwise). I've not seen specs, but one would think the plates needed to be separated to permit the tether service loop to be effective at reducing the transmission of any vibration along the stack of 5 semi rigid ribbon cables (umbilical tether) into SEIS. There is a recent YouTube video of the engineering team practicing deployment of the instrument (filmed at JPL) that showed them using the scoop on the end of the robotic arm to gently pull the pin on top of the tether pinning mass gently away from SEIS, that would open the plates and thus permit the service loop to do its job. Then we can look forward to seeing the deployment of the WTS

This Medieval Re-enactor pedant writes...

Is it not more like lorica squamata than maille?

Andy

It has both
See attached that I extracted from the SEIS page. The Chain Mail is behind and below the 'Lorica Squamata'. I simply added the annotations.
Click to view attachment

Oh! Gotcha! That's excellent!

You have the answer by Gabriel PONT @Gaby65 (SEIS Instrument Manager @CNES) on twitter :

"Le LSA (Load Shunt Assembly) de #Seissurmars a été ouvert avec succès. [...] La prochaine étape va terminer le boulot en ajustant la position du tether avec le bras de #insight."

"The Load Shunt Assembly (LSA) of #Seissurmars has been successfully opened. [...] The next step will finish the job by adjusting the position of the tether with the #insight arm."

The SEIS news page has just been updated (dated January 8, 2019)

French version LINK

As earlier, the English button on the news page only takes you to the SEIS front page, so here is a link to the Google translated version page.

English via Google translate LINK

Wonderful insight on this. thank you.

pun intended?

Stereo view of SEIS and cable from sol 42. Cross-eyed:
Click to view attachment
Anaglyph:
Click to view attachment