Tomorrow the Mars Rover “Perseverance” will land on the Red Planet at 3:55 p.m. Eastern U.S. time (2:55 Chicago time, 8:55 pm London time). You’ll want to be awake then, for the landing will be filmed live with several cameras! NASA has a countdown page here, which links to all kinds of information about the Rover and the mission. Tomorrow afternoon I’ll post some links where you can watch the landing, assuming that all goes well.
The landing sequence of this gizmo in Jezero Crater is known as “The Seven Minutes of Terror” because the slowing down of the spacecraft from 12,100 miles per hour to just 1.7 mpg right before landing takes seven minutes and a ton of complicated technology. All of that was recently programmed into the spacecraft and rover: since there’s an 11-minute delay between Earth and Mars communication, we won’t know whether the Rover has landed until it’s all over. And there’s nothing anybody can do to help at Mission Control.
Here’s a NASA animation showing how damn complicated this landing will be! It involves separation of the module containing the rover, deployment of a parachute, jettisoning of a heat shield, jets helping navigate over the surface to find a good landing spot, and most amazing, a “sky crane” that gently lowers the rover to the planet’s surface and then flies away.
It’s stunning that a mammalian species can pull off something like this. Don’t miss the live feed tomorrow!
This is a SCIENCE mission, and the rover will be landing in a crater that harbors an ancient delta. As Space.com reports,
Perseverance, or “Percy” for short, will explore the Martian terrain and conduct a number of science investigations. Among its objectives, Percy will collect samples, deploy the first helicopter beyond Earth, and search for signs of ancient life on the fourth planet from the sun.
And from the USA Today link above courtesy of NASA, a timeline of the landing:
I guess there will be sound, too, as there is an array of cameras and a microphone:
h/t: Tom
I will be watching! The shots of its own landing should be dramatic. My guess is that these images and videos won’t be available for a while due to the low transmission rate back to Earth. Still, watching all those scientists who’ve worked on it for years cheer its success (hopefully), is a good thing. Two other Mars probes have arrived successfully. Hopefully Perseverance will make it three for three.
As I understand it, there’s low-res transmission until atmospheric entry, then no contact during atmospheric braking, low res after parachutes open and heat shield is jettisoned, and ‘live’ low-res to the surface. Full video available a few minutes later — if it survives..
I guess the data links are much higher performance these days. It’s going to be spectacular, if it survives. Hopefully, its reuse of an earlier successful landing process will help a lot.
Yes, much better. Partly due to existing satellites in orbit capable of acting as a relay instead of the data having to go directly from Mars surface to Earth.
From the top of Mars’ atmosphere to the surface is the seven minutes of terror. But the radio signal’s time-of-flight to Earth is eleven minutes. Which is why the EDL is known as “seven minutes of terror” – whatever has happened has already happened, but we’re still watching the data coming in.
We’re not in the same inertial reference frame as Mars. As Einstein showed, “simultaneity” is not a concept that works outside one reference frame. It’s hard enough to get it to work within one reference frame.
I think it would be seven minutes regardless of our distance from Mars. The distance simply delays our knowledge of the events from start to finish. I think they call it “terror” because the hot entry through the atmosphere envelops the craft in a plasma that makes communication impossible. We only know what happened after the seven minutes when it communicates with us, or not.
I will be proctoring an online exam then, but maybe I can sneak a peak at the live stream during it!
Here’s an article about the audio equipment aboard the Perseverance rover — pretty cool. NASA has already released a recording made during its journey (of course no one can hear you scream in space, but this is apparently the sound the craft itself made). Amazingly the microphone is an off-the-shelf product, a premium mic used in classical music recording (by those who can afford them!).
Yes, recording the sounds of Mars will be very cool. A lot of stuff that goes up to space these days contains off-the-shelf components. The miniaturization of components for smartphones have been a boon for space science.
… and there isn’t a single ‘alternative ways of knowing’ that’s going to get you a genuine triumph of human discovery like this one. I hope a *lot* of people watch this and get the critical takeaway from seeing this kind of project come to fruition: science is real, it’s what works, it’s what gets you this kind of result. Nothing else comes close.
Well put.
It’s weird that NASA does all their engineering in SI units (meters, kilometres, kilograms, etc.), but has to put out graphics like the timeline of the landing with velocity in mph and altitude in miles or feet. Those graphics are for public consumption. I guess NASA thinks the American public is still really opposed to a sensible base-10 measurement system?
It’s not that weird given that Americans are notably resistant to the metric and Celsius systems. In fact, ask an American what -15 degrees Centrigrade is in Fahrenheit, or what 30 kilometers is in miles. Many of them simply couldn’t answer. We need to convert to the system the rest of the world uses, but I can’t see that happening any time soon.
The transition to metric system isn’t easy for the average person. In Canada we switched when I was about 40 years old. I wobble between the two systems and I am pretty good at estimates when I’m in familiar territory, say oz vs gm or kilometres vs miles, Anywhere else am I ‘bless’ the converters I find online.
On the other hand, my son, who lived and worked in the States for a while, appeared to be a genius to some of his coworkers in the trucking industry. The transition took place when he went into highschool and he learned to work with both systems and do conversions with ease. Thus the deceptive appearance of brilliance. 😀
I recently had to look up the inches-to-mm conversion factor because I only had 3 significant digits memorized, and I wanted more than 3-digit precision. Turns out, the inch is *defined* as 25.4 mm, exactly. So, in some sense, we’ve been using metric all along.
That is the only US measure I know exactly, and it isn’t because it is a pity conversion factor. Woodwork still used it the last century and it was among the first thing on measuring my father taught me.
But we have more or less completely inched away from it. 🙄
I’m comfortable working in both US and metric. But it can be hard to acquire metric measuring tools in the US. I used to do fine art installations and at one point started doing more and more work for European galleries, so I decided to buy a metric tape measure. Little did I know.
I couldn’t find any at all at any hardware stores. Even on the internet there was little to choose from that didn’t involve a shipping charge that was more than the tool cost because it had to ship from Europe. I only found 2 different ones that had regular, reasonable, shipping costs. I bought both. Both were cheap junk.
You couldn’t get any from Canada?
I don’t remember, but it is possible that the 2 that I bought were from Canada. They were not brands I’m familiar with and were not made in the US.
Or it may have been that any from Canada had high shipping fees. I recall shipping ranging from $50 to $85 for some of the tape measures.
I had to check but you’re right! Even though the common 12″ plastic ruler has one edge metric, both big roll-up tapes I have do not. Strange!
There were several “locally” available that had metric on one edge and US on the other, for example Stanley makes some like that, but I wanted all metric.
I just took a peak on Amazon. Looks like today it’s not a problem. But back in 2010 or so it was slim pickings.
Drawing on the UK’s experience of conversion to decimal currency, the solution is to give up on thinking “What is 10p in shillings?” / “What is 28 Celsius in Fahrenheit?” and just get used to what the new unit actually means in terms of itself. If you constantly need to convert a figure to the “real” unit you will get nowhere. (I say this as someone who was taught to measure things at school in centimetres many decades ago, but still answer questions about how tall I am in feet and inches.)
Not serious, off the top of my head, but how ’bout using degrees for C as usual—
But make it a crime punishable by a nude plunge through the ice in mid-winter if you fail to use ‘DUMBdedumbdegrees’ if talking F.—and needing to scramble out wearing a pair of 80 year old HEAVY skates.
At least the units for other things (miles/kilometres, …) haven’t the same name; whereas (degrees/degrees).
I confess that I would have to take at least a few seconds to mentally calculate: (9/5) (-15) + 32 = (-135/5) +32 = -27 + 32 = 2F. And of course calculating the value when C = F (-40 degrees). But, if one does something often enough, one memorizes it. Thus training (repetition) is distinguished from education. After more than 30 years I still indelibly recall as a deck officer on my navy ship, “All ahead Standard, 74 rpm’s for 15 knots.”
Of course, a mismatch of units resulted in the Mars Climate Orbiter landing failure in 1999: https://en.m.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure
I’m excited about this, and hoping for the best. The “sky crane” technique worked for Curiosity so there is reason for some confidence that it should work for Percy.
The gear gets better and better every mission. I’m looking forward to being amazed by the data Percy (and Ingenuity!) collects.
Two questions about this:
(A) The sky crane flies off and … just dies elsewhere on Mars?
(B) The video shows the sky crane doing little to give the rover a substantially different velocity than its own. But if I were designing such a thing – if I were smart enough to think of the idea in the first place, which is purely pretend – I would definitely use those cables to give the rover a soft landing while the sky crane had some other crazy velocity. How does it really work?
My understanding is that the sky crane tries to maintain a constant altitude while lowering the rover. Only when the rover touches down does it sever the cables, rev up its thrusters to fly off and crash at a safe distance. I’m not sure how it detects the touchdown, perhaps the cables going slack or via a radio link.
That’s pretty much it. As I remember it the rover tells the skycrane that it has comfortable footing on all wheels for long enough before the wire cutting. No radio link I think, there should also be a set of cables that will be cut.
A) Yes, after the tethers are cut, on the rover’s end via explosive bolts, the sky crane fly’s some distance away and then crashes, job done.
B) Once the parachute phase of the descent is over and the parachute is detached the rover + sky crane, slowed to a bit less than 200 mph (322 kph), fall freely for a second or so and then the sky crane’s engines fire up. It first performs a sideways maneuver to get clear of the falling parachute
There are sensors, ground sensing radar, that provide date for the sky crane. The sky crane slows the descent down to about 1.5 mph (2.4 kph). When it reaches about 100 ft (30 meters) above the surface the sky crane lowers the rover on 3 nylon tethers + a power & communication umbilical.
The sky crane then continues to descend at less than 1 mph (1.6 kph) until the rover touches down. Once the rover’s wheels are in constant contact with the surface for a second or so the tethers and umbilical are cut and the sky crane executes its fly away maneuver and then crashes.
So, yes indeed, the sky crane gives the rover a very soft landing. It’s practically hovering.
Let’s keep our fingers crossed!
Mars has been busy in the last few days! China and the United Arab Emirates have both just had probes arrive. At least we might find out where Princess Latifa is….
That’s a consequence of orbital mechanics. The shortest (time, or distance) route between Earth orbit and Mars orbit recurs approximately every 2 years, and the transfer season is coming up.
I’ll be watching! My wife’s name is on that thing!
This is very cool! Thank you for sharing it!
Converting to the metric system will be even more difficult than learning to drive a car in Britain. During
my first sojourn there, I solved the difficulty by driving on both sides of the road, which I continued to do in the USA upon returning. Afterward, when I returned to Britain for short visits, I invariably began
by getting on a bus going the wrong way.
Worst at first is remembering to look right, NOT left, when stepping out to cross a road.
I have driven quite far in all four modes: left-hand drive on both sides of the road (bought a ’63 LandRover and brought it from Britain to Canada); and right-hand drive on both sides–drove my old Brit Ford Cortina from Dover to France—>Norway, then roundtrip Oslo –> Bergen –> Stavanger.
Joke is the North American tourist, after 2nd roundabout, returns the car rental to Heathrow, and gets a BritRailPass.
American car in left- side drive in crazy Lagos, Nigeria, before they changed to the right side.
Ah, another graduate of the CIA School of Driving! The question is, will Sacoolas be bankrupted before or after she is arrested?
https://www.theguardian.com/uk-news/2020/may/11/interpol-red-notice-issued-for-arrest-of-anne-sacoolas
I’d bet on “before” – she knows if she sets foot outside the USA, she’s liable to arrest and deportation, and as an “intelligence agent” one would hope that she isn’t the bluntest spoon in the Pentagon drawer.
Having driven all combinations on several continents, it’s not that difficult swapping sides of the road. The worst bit is usually the first roundabout on leaving the vehicle pickup point. Traffic lights are easy if inefficient.
Exciting!
BST is EST plus 5, you’ve got 6.
Jerry’s Central Time?
“Planet earth is blue and there’s nothing I can do.” – Bowie
DAMN that is cool. I’ll be watching for sure. I’m not sure what it does when it arrives, though. Sort of scuttle about taking selfies? Still… cool.
D.A.
NYC