Well, you'd be wrong. And I grow quite weary of hearing that since I worked on that project for years and know exactly what happened. It was far more than a simple units mixup. [mods, feel free to delete this exchange as it is off-topic.]

Well, first, the public affairs people in NASA and related organizations add imperial units for public consumption. For human-familiar scales (pounds, inches) I can sort of understand. mph (up to a few hundred, perhaps, too)

The aerospace industry in the USA is a little schizoid on this matter, I'd say (as someone who works in it, but was trained in the UK). Every day mission designers are working in kilos, watts, m/s, kilometers altitude etc. Optical designers never refer to the wavelength of light in anything other than microns or nanometers. And the systems engineering project plan says SI is to be used throughout. And yet when you get to the mechanical side of things, inches and pounds get bandied around. Pressure vessels are in psi. In part this is infrastructure inertia, the machine tools which may be decades old are still graduated in inches, and the pressure gauges on big chambers too.

A wierd one is that radiation dose is specified in kRad (effectively an SI derived unit) *behind 100 mil of Al shielding* this is the worst IMHO as it is an imperial unit that is phonetically easily confused with millimeters. On those occasions when this abomination - milli-inches! - was referred to in the UK, at least some had the good grace to refer to it as a 'thou' (thousandth of an inch)

Anyway, the publisher (AIAA) for my forthcoming book on Ingenuity and Dragonfly insisted I put in Imperial equivalents. I did so on the human-familiar sort of items above, but it makes no sense to me to refer to the density of the Mars atmosphere in slugs per cubic foot......

So, it's complicated. You can expect to see these Renaissance units in use for quite some time

And Mike is quite right, the MCO failure was much more nuanced than just a units error.

Interestingly, flight level, in most of the world, uses units of 100 feet.

https://en.wikipedia.org/wiki/Flight_level

Star, flight operations were standardized in the first half of the last century and use Imperial units.

Yes! And especially during and after WWII : America made the planes that were then used worldwide and all pilots were trained on them
For example, the plane most used worldwide (and even after WWII as civil transport) was the incredibly reliable C-47 Skytrain "Dakota" (ex-Douglas DC-3)

You will note in the article in question : https://www.jpl.nasa.gov/news/nasas-mars-he...ance-rover-land : as is usual - both imperial and metric units are shown.

Given that the primary audience is the American public - it is only reasonable that the format is imperial ( metric )

Off topic but worth discussing and it must have been a wonderful experience to have been involved in that project, a job most of us amateurs could only dream of. I think the reason the public still considers the mishap to have resulted from a measurement unit mixup is because the board stated:

"The MCO MIB has determined that the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, “Small Forces,” used in trajectory models. Specifically, thruster performance data in English units instead of metric units was used in the software application code titled SM_FORCES (small forces). A file called Angular Momentum Desaturation (AMD) contained the output data from the SM_FORCES software. The data in the AMD file was required to be in metric units per existing software interface documentation, and the trajectory modelers assumed the data was provided in metric units per the requirements."

http://sunnyday.mit.edu/accidents/MCO_report.pdf

But as was also stated, the real problem was the fact the error went undetected which has little to do with the SI vs Imperial debate. The concept of error detection is certainly topical when discussing any remote mission, including Ingenuity, and probably what was learned after the MCO mishap has reduced the risk of all subsequent missions considerably.

...aaand that's enough already with the units/MCO debate. Please restrict further discussion on this thread to Ingenuity-related matters.

A few hours ago David Agle, the Media Representative at JPL published the status report #376 „NASA’s Ingenuity in Contact With Perseverance Rover After Communications Dropout” dated May 06, 2022. In particular, he informed that on May 3 (Sol 427) the rotorcraft had missed a planned communications session with the rover. After that


...

...


To help the helicopter’s battery accumulate enough of a charge during the next few sols so that it could support all necessary spacecraft systems during the cold Martian night, the team uplnked the following patch:



Please correct my understanding of the abovesaid.

1. The critical –15°C for the batteries is known from „Mars Helicopter Technology Demonstrator” (Bob Barlam et al., 2018, p. 15).

2. Meanwhile the heaters keep the temperature of vital helicopter components from dropping farther down to the ambient environmental temperature of –80°C.

Question 1: what is the trigger event to turn the heaters on: (1 - batteries’ t°) or (2 - air t°)?

Question 2: If I am right, that the critical t° to start heating now is moved from –15°C to –40°C, then shall the batteries themselves survive that temporary „freezing” each night?

-- thank you, Cherurbino

The status report #376 „NASA’s Ingenuity in Contact With Perseverance Rover After Communications Dropout” dated May 06, 2022:



Meanwhile, the Perseverance Rover Daily Weather Report (https://mars.nasa.gov/mars2020/weather/) observed the first occurence of t° < 80° as early as an April 27. How could Ingenuity sustain that?

Without knowing the specifics of the cells used, I'd offer the following generic remarks

1. -15C is not really a 'critical' temperature, there is merely a progressive degradation of performance towards lower temperatures. In development, a conservative value might be designated 'critical' in that with certain assumptions, the probability of achieving mission objectives may decline below some acceptable level. Then other subsystem designers adopt that value and strive to meet it. In practice, there are margins built-in because the failure probabilities are not exactly known, designs may need to assume worst-case dust in the atmosphere or other factors that are not known well until after the mission begins. It isnt a given that freezing of the electrolyte always leads to permanent damage, it will depend on the design of the cell.

2. For an electrochemical system like a battery, one can consider a parameter space of state-of-charge vs temperature. Operations (charge/discharge/use of heaters) will define trajectories in that space. Some trajectories (subject to boundary conditions like dust loading, air temperature etc.) may maximize the state of charge at the end of night, giving the most energy to perform a flight the next day, for example. These trajectories may well be different from those trajectories which minimize the degradation of the battery (e.g. the capacity). So one year on, with the objectives achieved and a lot of stuff going on, the emphasis has probably shifted to enhancing the former performance metric, thus allowing lower cell temperatures but spending less night-time energy on heaters. This may imply an acceptance of higher probability of degradation in the long term.

Note that the optimal storage temperature of a battery that is not being used (e.g. on the Huygens probe during cruise) may be lower than the preferred temperature during charging or discharging.

So the press release remarks are perforce simple for journalistic consumption, but the engineering reality is that there are some complex tradeoffs.

Ralph

Thank you, Ralph, for your answer. Hypothetically I could bring here the datasheets for these cells, graphs for their charging at different rates, quotations from papers I used in my work under the article at Wikipedia... however my bad experience with asking questions to the JPL specialists made my choice to keep silence until anybody else shows the interest. Imposing a discussion on a subject which is no interest to anybody but me is not a good idea.

If 'Ingenuity' shall be able to perform its 29th flight, I shall be very glad to change the statement ' –15 C is the critical temperature', to smth. like '–15 C was conservatively suggested to be critical until flight #29'.

Cherurbino

Actually, that isnt quite true either. When I got Teddy Tzanetos to fact-check the Ingenuity chapters of my book, where I had quoted that -15C number (since that's what is in the papers that were available at the time) he pointed out that in fact on the nights before a flight they relaxed it to -20C to improve the state of charge. I'm not sure when that policy started, but certainly the -15C is not a hard and fast number now, and hasnt been since well before flight 29..

The Ingenuity team's efforts to work through these temperature and battery problems remind me of the early months of the Opportunity mission, when the Rover team began to use “Deep Sleep” to conserve power by forcing a stuck shoulder joint heater to turn off at night.

That was on Sol 121. A contemporary AP account cautiously predicted that Opportunity and Spirit “may last for several more months.”

We’ll see.

Thanks as always to Ralph for sharing his expertise. Looking forward to reading Planetary Exploration with Ingenuity and Dragonfly.

Yesterday, on May 26 (sol 449) Perseverance received two photos from helicopter shot at 15:29:32 (color) and at 15:29:53 (b/w).

The color photo was transmitted partially. The reason could be the energy defict (color photos are too 'heavy' for transmission, about 23 MB each). However good news are that the experiments of Ingenuity's team with changing the heating regime did not harm the accumulators. Helicopter is still alive and continues to accumulate energy. Whether is shall be enough to perform Fllight #29, the future shall show.

In the past week or so hundreds of Heli_NavCams and a few RTE images have appeared on the M20 image server (from earlier flights).

One could probably assume they have been conducting an image dump from the helicopter as power levels and communications sessions permited.

One could also assume that once the image dump is complete that we could see them plan flight #29

https://twitter.com/balaram/status/1530953553220468736

This tweet from Ingenuity's Bob Balaram links to a video of a talk he just gave.

It includes this JPL map:

Click to view attachment

... which has some names on it. Yori Pass up on the cape at left. A cluster I can't disentangle where Perseverance is now. 'bacon strip' might be White Rocks. Polygon Valley is east of Seitah, not on its edge as I had assumed so I will have to change a map. And can anyone figure out the name of the hill south of Santa Cruz on the right edge? It looks like 'Mauna Kali---' and it is in a quadrangle where names should be from Hawaii, but it doesn't look like the obvious Mauna Kea.

Phil

Phil, after exhaustive search I think the name must be Mauna Kahalawai as is the only name on Maui that fits. The quad in question is named after
Haleakalā National Park, but I could not find any appropriate name inside the park's border. See my new map with all the new names in the map section.

Jaka

In the course of his lecture Bob asked to enlarge this slide, but nobody helped him. Maybe the slides shall be available on the site of the Society where Balaram read his lecture?

Among the names unknown to me before are: Martre on slide for Flight #12

This can’t be better : https://twitter.com/stim3on/status/1533494858962415616?s=21

Nice! That lets us compare it to the MRO imagery.

Indeed, Hungry4info.. Did Ingenuity ever get decent-resolution images of the descent bus?

--Bill

Last news : https://mars.nasa.gov/technology/helicopter...aag-dF.facebook

It ain't called "Ingenuity" for nothing. Bravo.

NASA's Ingenuity Mars Helicopter acquired this image using its navigation camera. This camera is mounted in the helicopter's fuselage and pointed directly downward to track the ground during flight.
This image was acquired on Jun. 11, 2022 (Sol 465 of the Perseverance rover mission) at the local mean solar time of 15:28:52

--
29th flight was OK?

"The raw data is down and Ingenuity had a successful Flight #29 which puts it in a better communication position with the rover!
Despite the recent problems, this little guy just keeps on persevering! "

https://twitter.com/sfsholes/status/1536419606599852032

The interactive map and the waypoints JSON have both been updated for Ingenuity's flight #29
Click to view attachment Click to view attachment

For the record: Ingenuity Postpones Flights Until August

I wish there was a way to get a peek at the dust accumulation on Ginny's solar panel. I guess we can estimate that from views of Perseverance's topside and from voltage telemetry when we get it.
As a sidenote, I've not flown my GinnyJr since this brutally hot weather has hit! More fun to come in the cool Fall days.

Strictly, it's the array current, not the voltage, that is proportional to the light flux.... ;-) But yes, that housekeeping data will be interesting

related open access articles
https://www.sciencedirect.com/science/artic...214242814000229
https://agupubs.onlinelibrary.wiley.com/doi...29/2019EA000992

A new RTE ground photo from Airfield 'U' acquired on June 18, 2022 at the LMST of 12:33:22 appeared in the stock. The file is erroneously attributed in the caption as 'Mars Helicopter Sol 465: Color Camera' (should read 'sol 475') and in the description ('This was the date of Ingenuity's 29th flight').

4 new RTE ground photos from sol 503 at Site 29 (Airfield U) are now on the server.
They have different timestamps and there are small movements in the shadows between frames.
Possibly giving the actuators on the rotors a workout (wiggle?) to remove dust?
Link to all the site 29 RTE images https://mars.nasa.gov/mars2020/multimedia/r...amp;af=HELI_RTE

Click to view attachment

Maybe "wiggling the stick", but possibly due to wind rocking the 'copter? It's relatively light but has a large surface area for the wind to act on. I've observed MiniGinny rock from the wind.
Those are great images.

--Bill

The shadow of the leg shifts too - isn't the shadow movement simply due to the movement of the sun over the nearly one minute interval of the three sol 503 images?

Looks that way in the animation.

Looks like a possible rotor spin in sol 527.
Processed NavCam's and GIF

Click to view attachmentClick to view attachment
GIF: Click to view attachment
Timestamps show less than 2 minutes between frames

Impressive longevity.

--Bill

Sol 533, just had a very short test flight.

Phil

Dear colleagues, one bibliographic question, if you allow. This summer I came across one article about Ingenuity's rotor. If was a kind of an interview with one of JPL engineers who personally assembled the rotor including manual winding of thin copper wires which took him a given number of hours. The article was illustrated with a photo of rotor.
Did anybody read this article? Where was it published? I've lost its traces in my records.

--Thanks in advance, Cherurbino

I don't know of the specific article to which you refer, but this sounds like Ben Pipenberg at Aerovironment. That company, not JPL, designed and assembled the motors and rotors. My new book ('Planetary Exploration with Ingenuity and Dragonfly", published by AIAA last week) gives details....

Found it. Is there a better source than Amazon? I looked on the AIAA site, no luck.

https://www.amazon.com/Planetary-Exploratio...g/dp/1624106366

Thank you, Ralph - first for writing this book , and then for answering.

In the bibliography of my Wikipedia article I linked your book to https://arc.aiaa.org/doi/10.2514/5.9781624106378.0073.0086 where it is dated slightly earlier (24 Jun 2022). This mismatch is not significant, in these cases I follow the rule "earlier is better". Worse is that I can read only the first pages of chapters 4 (p.73), 5 (p.87) and 6 (p.109) and can only guess what new information I may find there to be quoted and inline-referenced in Wikipedia.

For example, I guess you could mention, that the first simulations in the 80" chamber were carried not with the full-scale, but with the miniaturized prototypes. On 2021/04/09 the dailynews.com mentioned 14-inch rotors. If you cover this issue, the reference to your book shall look more reliable than a link to the dailynews.com )) but I need a page number for that.

-----
Bill Harris:
Thank you, see my link above in this post.

https://arc.aiaa.org/doi/book/10.2514/4.106378

[quote name='Cherurbino' date='Aug 24 2022, 02:23 PM' post='258192']

For example, I guess you could mention, that the first simulations in the 80" chamber were carried not with the full-scale, but with the miniaturized prototypes....... If you cover this issue, the reference to your book shall look more reliable than a link to the dailynews.com )) but I need a page number for that.

-----

Pages 87-91 discuss the different test models, noting for example that the first small-scale article was tested in a small (10-ft?) chamber. Then there was a 'Phase 3' vehicle, which had full-scale rotors, but had cyclic controls only on the lower rotor and collective only on the upper one, and both rotors were driven by a single motor via gears. There were subsequent higher-fidelity Engineering Development Models (EDMs) which had cyclic control on both rotors and individual direct drive motors for each rotor. It took some discussion with the team to ferret out these details....

The Book is ordered.
I've enjoyed flying my Ingenuity mockup, but I'm looking forward to doing a Dragonfly mockup. That should be easily do-able with conventional Quadcopter hardware.

--Bill

Another interesting details of early modelling phases were published at https://insidegnss.com/inside-ingenuity-wit...i-designing-it/
The pdf version of these interviews is available at https://www.avinc.com/images/uploads/news/IUS_Ingenuity.pdf.

Matt Keennon (joined AeroVironment in 1996, AV’s technical lead for the rotor system development on the Mars Ingenuity Helicopter Program and an AeroVironment principal electrical engineer):



Ben Pipenberg (joined AV in 2014, AV’s engineering lead on the Mars Ingenuity Helicopter Program and AeroVironment senior aeromechanical engineer; worked on sub-scale, larger demonstrators and the final build.)



Is my guess that "the JPL chief engineer for the program" was Bob Balaram (his name is not mentioned)?

Fascinating! See this video by user 65dbnoise on fosstodon:

https://fosstodon.org/@65dBnoise/109083599885475082

(many very useful posts there, not just this one).

It shows Ingenuity's flight 33, but look at the footpad at upper left: a bit of EDL debris hanging off the leg. It drops off later. Amazing, and not a little worrying if it gets into places it should'nt.

Phil

Here is Ingenuity at 672 m : https://twitter.com/wolfiesmiffed/status/15...GRjZ6osZDX8LZjg

Was it seen on the previous flight? It looks like it wrapped around that footpad. Could it have been blown in with the wind?
This is a concern because ir could foul a rotor.

--Bill