APOD: Perseverance: How to Land on Mars (2021 Feb 20)

[APOD Robot]

Perseverance: How to Land on Mars

Explanation: Slung beneath its rocket powered descent stage Perseverance hangs only a few meters above the martian surface, captured here moments before its February 18 touchdown on the Red Planet. The breath-taking view followed an intense seven minute trip from the top of the martian atmosphere. Part of a high resolution video, the picture was taken from the descent stage itself during the final skycrane landing maneuver. Three taut mechanical cables about 7 meters long are visible lowering Perseverance, along with an electrical umbilical connection feeding signals (like this image), to a computer on board the car-sized rover. Below Perseverance streamers of martian dust are kicked-up from the surface by the descent rocket engines. Immediately after touchdown, the cables were released allowing the descent stage to fly to a safe distance before exhausting its fuel as planned.

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[Chris Peterson]

What I remember from Viking was the way that everything was custom, everything was hardened, every gram was counted. Increasingly, we're seeing newer technology, off-the-shelf parts, and luxury "fluff" like video on the skycrane, audio, and other stuff that simply wouldn't have been considered in the past. What we're seeing, I think, is spacecraft engineering settling into a comfort zone, a kind of routine. (That isn't meant to take anything away from that engineering, which is obviously first rate. It's a good thing that the comfort and confidence levels have risen to the point that this kind of stuff can be included.)

[ZootMurph14]

Is the video of this occasion online somewhere to be viewed. I would love to see it.

[De58te]

What I find fascinating besides this landing itself is also the nature of reality pertaining to astronomical light speed and likewise radio wave speed. Here we read that the landing sequence took 7 minutes. On the NASA tv site in the pre landing discussion I heard that the planet Mars was about 11 light minutes away from Earth. So that means that when I was watching on NASA the 'live' landing, and the announcer began to say, while all the technicians were intensely watching their monitors, that Mars 2020 had begun landing sequence. Speed is 12 kilometers per second. Then moments later the parachute has been deployed successfully, speed 9 kilometers a second - that in reality Perseverance was already sitting on the ground of Mars for over 3 minutes! So why all the anxiety about the speed. The rover was already safely on the ground or one smoking pile of wreckage.

[JohnD]

De58te,
Sir, you are a steely-eyed rocket man!
Or else, you really don't understand the situation, and how the mission controllers felt as they waited to know the awful truth!

[orin stepanek]

Little Rover dropped on Mars;
Sleeker than our Earthly cars!🏎

[Phobos1]

It's so SHINY!
Well, that'll change in a year or two.

[johnnydeep]

Perseverance: How to Land on Mars

Explanation: Slung beneath its rocket powered descent stage Perseverance hangs only a few meters above the martian surface, captured here moments before its February 18 touchdown on the Red Planet. The breath-taking view followed an intense seven minute trip from the top of the martian atmosphere. Part of a high resolution video, the picture was taken from the descent stage itself during the final skycrane landing maneuver. Three taut mechanical cables about 7 meters long are visible lowering Perseverance, along with an electrical umbilical connection feeding signals (like this image), to a computer on board the car-sized rover. Below Perseverance streamers of martian dust are kicked-up from the surface by the descent rocket engines. Immediately after touchdown, the cables were released allowing the descent stage to fly to a safe distance before exhausting its fuel as planned.

As ZootMurph14 wished, so do I: "where's the video!" So, the rover is "a few meters above the surface" - let's call it at least 3 - and the cables are 7 meters long, and the rocket engines on the descent stage STILL managed to kick up some dust from at least 10 meters below! I presume that not all of that dust was so obliging as to not land on the rover, but hopefully not much did. Then again, hopefully, over time, just as with Spirit and Opportunity, the Martian wind will just as often blow dust off the Perseverance as on to it!

[Chris Peterson]

Perseverance: How to Land on Mars

Explanation: Slung beneath its rocket powered descent stage Perseverance hangs only a few meters above the martian surface, captured here moments before its February 18 touchdown on the Red Planet. The breath-taking view followed an intense seven minute trip from the top of the martian atmosphere. Part of a high resolution video, the picture was taken from the descent stage itself during the final skycrane landing maneuver. Three taut mechanical cables about 7 meters long are visible lowering Perseverance, along with an electrical umbilical connection feeding signals (like this image), to a computer on board the car-sized rover. Below Perseverance streamers of martian dust are kicked-up from the surface by the descent rocket engines. Immediately after touchdown, the cables were released allowing the descent stage to fly to a safe distance before exhausting its fuel as planned.

As ZootMurph14 wished, so do I: "where's the video!" So, the rover is "a few meters above the surface" - let's call it at least 3 - and the cables are 7 meters long, and the rocket engines on the descent stage STILL managed to kick up some dust from at least 10 meters below! I presume that not all of that dust was so obliging as to not land on the rover, but hopefully not much did. Then again, hopefully, over time, just as with Spirit and Opportunity, the Martian wind will just as often blow dust off the Perseverance as on to it!

Well, since this rover uses a RTG power source, not solar panels, I don't think dust is a major concern.

[johnnydeep]

Perseverance: How to Land on Mars

Explanation: Slung beneath its rocket powered descent stage Perseverance hangs only a few meters above the martian surface, captured here moments before its February 18 touchdown on the Red Planet. The breath-taking view followed an intense seven minute trip from the top of the martian atmosphere. Part of a high resolution video, the picture was taken from the descent stage itself during the final skycrane landing maneuver. Three taut mechanical cables about 7 meters long are visible lowering Perseverance, along with an electrical umbilical connection feeding signals (like this image), to a computer on board the car-sized rover. Below Perseverance streamers of martian dust are kicked-up from the surface by the descent rocket engines. Immediately after touchdown, the cables were released allowing the descent stage to fly to a safe distance before exhausting its fuel as planned.

As ZootMurph14 wished, so do I: "where's the video!" So, the rover is "a few meters above the surface" - let's call it at least 3 - and the cables are 7 meters long, and the rocket engines on the descent stage STILL managed to kick up some dust from at least 10 meters below! I presume that not all of that dust was so obliging as to not land on the rover, but hopefully not much did. Then again, hopefully, over time, just as with Spirit and Opportunity, the Martian wind will just as often blow dust off the Perseverance as on to it!

Well, since this rover uses a RTG power source, not solar panels, I don't think dust is a major concern.

Ah, thanks, I forgot about that! I always did think solar power was too tenuous a power solution to bet your mission on. Three cheers for radioactivity!

[bls0326]

The "skycrane landing" link has a good animation of the entire landing sequence.

https://mars.nasa.gov/mars2020/timeline ... t-landing/

[MarkBour]

The parachute deployment at 1530 km/hr is the most incredible moment to me. The atmosphere of Mars is thinner than Earth's but still, this parachute, the result of NASA's ASPIRE project, is the unrivalled champion of all parachutes. It can produce and tolerate over 30,000 kg of drag force.

Click to play embedded YouTube video.

[JohnD]

Thank you, MarkBour! Althought that tiny video just shows what happens, not how, it's still a fascinating part of the solution.

[XgeoX]

I can imagine Slim Pickins riding this thing down to Mars!

[johnnydeep]

The "skycrane landing" link has a good animation of the entire landing sequence.

https://mars.nasa.gov/mars2020/timeline ... t-landing/

Great animation/video!

[orin stepanek]

I'm ready to see more pictures of what Perseverance finds out there!

[neufer]

Perseverance

---

I'm ready to see more pictures of what Perseverance finds out there!

News Briefing: Mars 2020 Perseverance Rover Update
Feb. 22 at 2 p.m. EST [2/22/2021 at 2]

https://mars.nasa.gov/mars2020/timeline ... ch-online/

[orin stepanek]

https://mars.nasa.gov/mars2020/timeline ... ch-online/

Thanks Art: I'm gonna watch!

[JohnD]

Go home, Earthlings!
https://www.reddit.com/r/memes/comments ... arthlings/

John
Why can't I post a copy of that pic here, or upload a copy from my hard disc?

[johnnydeep]

Go home, Earthlings!
https://www.reddit.com/r/memes/comments ... arthlings/

John
Why can't I post a copy of that pic here, or upload a copy from my hard disc?

You mean the pic with the obscenity? It's a small jpeg and shouldn't pose any technical problem. I'd try posting it myself, but I don't want to incur the wrath of any censors here. (I can't imagine - well, I can, but it seems unlikely - an OCR censor would be smart enough to disallow the pic.)

EDIT: fixed to use "censor" instead of "sensor". (Thanks, neufer.)

[neufer]

Go home, Earthlings!

https://www.reddit.com/r/memes/comments ... arthlings/

Why can't I post a copy of that pic here, or upload a copy from my hard disc?

You mean the pic with the obscenity? It's a small jpeg and shouldn't pose any technical problem. I'd try posting it myself, but I don't want to incur the wrath of any sensors here. (I can't imagine - well, I can, but it seems unlikely - an OCR sensor would be smart enough to disallow the pic.)

sensor (n.) 1947, from an adjective (1865), a shortened form of sensory: 1749, "pertaining to sense or sensation," from Latin sensorius, from sensus, past participle of sentire "to perceive, feel".
.........................................
censor (v.) 1833, "to act as a censor (of news or public media); from censor (n.).
................................
censor (n.) 1530s, "Roman magistrate of 5c. B.C.E. who took censuses and oversaw public manners and morals," from French censor and directly from Latin censor, from censere "to appraise, value, judge," from PIE root *kens- "speak solemnly, proclaim" (source also of Sanskrit amsati "recites, praises," asa "song of praise").

They also had charge of public finances and public works. Transferred sense of "officious judge of morals and conduct" in English is from 1590s. Latin censor also had a transferred sense of "a severe judge; a rigid moralist; a censurer."

From 1640s as "official empowered to examine books, plays (later films, etc.) to see they are free of anything immoral or heretical." By the early decades of the 19c. the meaning of the English word had concentrated into "state agent charged with suppression of speech or published matter deemed politically subversive."
.........................................
censer (n.) "vessel used for burning incense before an altar," mid-13c., from Old French censier, a shortened form of encensier, from encens "incense" late 13c., "gum or other substance producing a sweet smell when burned," from Old French encens (12c.), from Late Latin incensum "burnt incense," literally "that which is burnt," noun use of neuter past participle of Latin incendere "set on fire" (see incendiary). Meaning "smoke or perfume of incense" is from late 14c.

[johnnydeep]

Go home, Earthlings!

https://www.reddit.com/r/memes/comments ... arthlings/

Why can't I post a copy of that pic here, or upload a copy from my hard disc?

You mean the pic with the obscenity? It's a small jpeg and shouldn't pose any technical problem. I'd try posting it myself, but I don't want to incur the wrath of any sensors here. (I can't imagine - well, I can, but it seems unlikely - an OCR sensor would be smart enough to disallow the pic.)

sensor (n.) 1947, from an adjective (1865), a shortened form of sensory: 1749, "pertaining to sense or sensation," from Latin sensorius, from sensus, past participle of sentire "to perceive, feel".
.........................................
censor (v.) 1833, "to act as a censor (of news or public media); from censor (n.).
................................
censor (n.) 1530s, "Roman magistrate of 5c. B.C.E. who took censuses and oversaw public manners and morals," from French censor and directly from Latin censor, from censere "to appraise, value, judge," from PIE root *kens- "speak solemnly, proclaim" (source also of Sanskrit amsati "recites, praises," asa "song of praise").

They also had charge of public finances and public works. Transferred sense of "officious judge of morals and conduct" in English is from 1590s. Latin censor also had a transferred sense of "a severe judge; a rigid moralist; a censurer."

From 1640s as "official empowered to examine books, plays (later films, etc.) to see they are free of anything immoral or heretical." By the early decades of the 19c. the meaning of the English word had concentrated into "state agent charged with suppression of speech or published matter deemed politically subversive."
.........................................
censer (n.) "vessel used for burning incense before an altar," mid-13c., from Old French censier, a shortened form of encensier, from encens "incense" late 13c., "gum or other substance producing a sweet smell when burned," from Old French encens (12c.), from Late Latin incensum "burnt incense," literally "that which is burnt," noun use of neuter past participle of Latin incendere "set on fire" (see incendiary). Meaning "smoke or perfume of incense" is from late 14c.

Yeah, I thought I might have had that wrong. Fixed now.

[Chris Peterson]

EDIT: fixed to use "censor" instead of "sensor". (Thanks, neufer.)

An OCR sensor might censor the image, preventing censure from a moderator.

[johnnydeep]

EDIT: fixed to use "censor" instead of "sensor". (Thanks, neufer.)

An OCR sensor might censor the image, preventing censure from a moderator.

Yup. But I did only mean an "OCR censor" at the time I first wrote it... Sensei