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Emily Lakdawalla Profile picture
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21 Feb, 10 tweets, 3 min read
While we wait for raw images, maybe I’ll try to beat down some conspiracy theories....
This image was only partially transmitted from Mars in moments after landing, before relay orbiter sank below horizon. The rounded upper left and right corners are the edges of the lens cap. The rounded edges to the black areas of no image data are JPEG compression artifacts.
The two images in this photo are the ones that were released on the raw images website already. They are thumbnail (down sampled) images, small versions that the rover transmits to Earth before downlinking more bandwidth-hungry full-res data.
Not a conspiracy theory, but it is something I can explain: yes, the raw images website did initially show eight images. The extras were just different versions of the same images, something that often happens with the automated pipeline when they’re first starting it up.
Yes, in fact the Curiosity raw images page had the entire descent in thumbnail form very soon after landing. Folks around the world who are a lot better at image processing than I am made many different amazing videos out of it before the full-res came down. It was wonderful!
(One of my favorite things about the international image processing community is how many different ways they come up with to process the same data set. So many points of view, each highlighting a little part of the whole in its uniquely creative way.)
Definitely not a tech problem, I promise. All I’ve heard indicates that all is well on the mission.
Also that video that’s going around that has millions and millions of views that is being shared as a Perseverance panorama with sound from Mars is...not. It’s a very pretty Curiosity panorama, with an artist’s concept of what it might sound like.
(Sorry, this thread has veered from conspiracy theories, now it’s just answers to questions)

NASA has requirements on missions about image release. Curiosity and Perseverance have same requirements: immediate release of engineering cam images, science cam images within 24h (1/2)
Science instrument principal investigators can decide whether they want to use 24h delay or release instantly or anything in between. Curiosity Mastcam PI (Malin) took full 24h delay. Curiosity MAHLI PI (Edgett) released instantly. Perseverance Mastcam-Z PI (Bell) says instant.

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More from @elakdawalla

Emily Lakdawalla Profile picture
21 Feb
I think the reason I’m so frustrated about the lack of raw images is that they have, until now, been the focus of my post-landing writing. There’s a new mission on Mars and I want to TEACH!! So, okay, I don’t get to do it with pictures. Ask me anything. I’ll answer as I cook.
By end of mission Perseverance may drive VERY far from safe landing site. By dropping samples closer to flat crater floor, it will be faster/safer/easier to retrieve & return them to where they can be launched to Mars orbit.
No, in fact rovers deliberately take more images than they can ever return to Earth. Each camera has its own storage & transmits files to main rover computer when commanded for downlink; others flow automatically according to assigned priority, from 1 to 100.
Read 18 tweets
Emily Lakdawalla Profile picture
20 Feb
A couple people who've been reading the Maki et al. (2020) paper describing the engineering cameras have pointed out this passage to me, talking about the EDL cams transmitting MPEG video to Earth. Here, let me explain what this passage says: (thread)
1) Like all Perseverance's instruments, the EDL cams have their own computer(s) inside the rover belly. When they acquire data, the data are stored in uncompressed binary format in the EDL cams' computer (the DSU).
2) The DSU can compress, downsample, & reformat the images.
3) After compression, the original raw files are still there on the DSU until their deletion is commanded by instrument engineers.
4) Because of the quantity of data, most of it will be compressed in MPEG format before transfer to Earth. HOWEVER,
Read 5 tweets
Emily Lakdawalla Profile picture
20 Feb
It is now 2 full sols after @NASAPersevere landed, and still there are no raw images being posted at mars.nasa.gov/mars2020/multi… . On every previous Mars mission since the MERs landed in 2004, these pages have given us all views of the daily operations of @NASA's Mars missions.
We were able to follow mission events by looking at the raw images feed. By now, @NASAPersevere should have deployed its high-gain antenna. Today is the day its mast should raise vertical, giving the Navcams, Mastcam-Z, and Supercam their first light on Mars.
The worst thing about @NASA @NASAJPL @NASA_Persevere's failure to follow Spirit, Opportunity, Phoenix, Curiosity, and InSight and post raw images is that mission team members can't be excited in public about the great successes they're having. They've been silenced.
Read 15 tweets
Emily Lakdawalla Profile picture
20 Feb
Landing plus 34 hours and there are still only 2 1/4 images here. What's going on @NASAPersevere? mars.nasa.gov/mars2020/multi…
The worst thing is, I've heard nothing official. If an official @NASAPersevere person told me "there will be nothing posted until Monday" I would be upset, but at least I could leave my F5 key for the weekend. Don't you want me to be excited? Can you tell me either way?
To everybody replying to this with "maybe something has gone wrong" I suppose it's possible but I have a lot of friends in the mission and I keep their secrets but I think I'm not betraying anybody's confidence when I assure you all that I've heard of nothing being wrong.
Read 4 tweets
Emily Lakdawalla Profile picture
19 Feb
Many others will be sharing photos this morning. I'm going to do something different: read through Maki et al. (2020), the paper describing Perseverance's engineering cameras, and provide you some context for those pictures. link.springer.com/article/10.100…
First: What and Where are the cameras? From left:
- 3 Parachute Uplook Cameras (PUC), mounted to backshell
- 1 Descent Downlook Camera (DDC), mounted to descent stage, pointing at rover
- 1 each Rover Uplook & Rover Downlook Camera, mounted to top & bottom of rover deck
- 2 Navcams, on mast, for surveying landscape for driving
- 6 Hazcams, on rover body, 4 front & 2 rear. Only 1 front pair is in use at a time (others are for redundancy), for surveying near field for drive safety & arm positioning
- 1 Cachecam inside rover body for sample images
Read 19 tweets
Emily Lakdawalla Profile picture
19 Feb
Those of you waiting for Perseverance pics: I'm about to do y'all a service. I have a radio interview in 7 minutes. They will certainly arrive while I am busy doing that.
Speaking of: listen in!
Standing by, will be on after the commercial break
Read 4 tweets

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