Curiosity MSL (Mars Science Laboratory) - Atlas V 541 - Canaveral SLC-41 - 26.11.2011

[Дмитрий Виницкий]

Как цирковые номера выглядят потуги всяких клоунов пукнуть на арене погромче по этому и другим поводам. Где вы были во время подготовки Фобос-Грунта?

[Сергио]

Как цирковые номера выглядят потуги всяких клоунов пукнуть на арене погромче по этому и другим поводам. Где вы были во время подготовки Фобос-Грунта?

резал провода к полукомплекту.

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Началось сближение.

MSL Approach Phase
http://www.unmannedspaceflight.com/index.php?showtopic=7347

We're now 45 days from landing, so as of 23 Jun please post all comments related to the end of the transit to Mars here.

Go Curiosity!!!!

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AUGUST 5 2012[/size]

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Марсоход Curiosity обязательно найдет свидетельства развитой цивилизации на Красной планете: любые образцы пород, за изучение которых возьмётся аппарат, будут загрязнены его собственным тефлоном.

Проект стоимостью $2,5 млрд нацелен на поиск углеродсодержащих молекулярных остатков жизни, возможно населявшей древний Марс. Набор измерительных приборов Sample Analysis at Mars займётся образцами, добытыми с помощью бурения или простого зачерпывания. Технология сверления была тщательно протестирована на Земле. Но теперь выясняется (и об этом сообщает само NASA), что в результате в образцы попадут частицы тефлонового покрытия сверла – и как раз в той концентрации (несколько частей на миллион), в которой органическое вещество присутствует в земных породах. Две трети тефлона составляет углерод – как раз тот элемент, который ищут на Марсе.

Лабораторные испытания резервной копии буровой установки обнаружили проблему незадолго до запуска марсохода, который состоялся в ноябре прошлого года. Участники проекта, однако, полны оптимизма: они верят в то, что к тому времени, когда Curiosity достигнет места назначения, решение будет найдено. Например, загрязнение можно свести к минимуму, изменив режим работы сверла. К тому же концентрация тефлона в образцах не ставит под угрозу сам бур или остальные части системы отбора и анализа проб. Кроме того, при нагреве образца в специальной камере до 600

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Curiosity Rover on Track for Early August Landing
Mission Status Report

PASADENA, Calif. -- A maneuver on Tuesday adjusted the flight path of NASA's Mars Science Laboratory spacecraft for delivering the rover Curiosity to a landing target beside a Martian mountain.

The car-size, one-ton rover is bound for arrival the evening of Aug. 5, 2012, PDT (early Aug. 6, EDT and Universal Time). The landing will mark the beginning of a two-year prime mission to investigate whether one of the most intriguing places on Mars ever offered an environment favorable for microbial life.

The latest trajectory correction maneuver, the third and smallest since the Nov. 26, 2011, launch, used four thruster firings totaling just 40 seconds. Spacecraft data and Doppler-effect changes in radio signal from the craft indicate the maneuver succeeded. As designed by engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., the maneuver adjusts the location where the spacecraft will enter Mars' atmosphere by about 125 miles (200 kilometers) and advances the time of entry by about 70 seconds.

"This puts us closer to our entry target, so if any further maneuvers are needed, I expect them to be small," said JPL's Tomas Martin-Mur, the mission's navigation team chief. Opportunities for up to three additional trajectory correction maneuvers are scheduled during the final eight days of the flight.

The maneuver served both to correct errors in the flight path that remained after earlier correction maneuvers and to carry out a decision this month to shift the landing target about 4 miles (7 kilometers) closer to the mountain.

It altered the spacecraft's velocity by about one-tenth of a mile per hour (50 millimeters per second). The flight's first and second trajectory correction maneuvers produced velocity changes about 150 times larger on Jan. 11 and about 20 times larger on March 26.

Shifting the landing target closer to the mountain, informally named Mount Sharp, may shave months off the time needed for driving from the touchdown location to selected destinations at exposures of water-related minerals on the slope of the mountain.

The flight to Mars has entered its "approach phase" leading to landing day. Mission Manager Arthur Amador of JPL said, "In the next 40 days, the flight team will be laser-focused on the preparations for the challenging events of landing day -- continuously tracking the spacecraft's trajectory and monitoring the health and performance of its onboard systems, while using NASA's Deep Space Network to stay in continuous communications. We're in the home stretch now. The spacecraft continues to perform very well. And the flight team is up for the challenge."

Descent from the top of Mars' atmosphere to the surface will employ bold techniques enabling use of a smaller target area and heavier landed payload than were possible for any previous Mars mission. These innovations, if successful, will place a well-equipped mobile laboratory into a locale especially well suited for its mission of discovery. The same innovations advance NASA toward capabilities needed for human missions to Mars.

A video about the challenges of the landing is online at: http://go.nasa.gov/Q4b35n or http://go.usa.gov/vMn .

As of June 27, the Mars Science Laboratory spacecraft carrying the rover Curiosity will have traveled about 307 million miles (494 million kilometers) of its 352-million-mile (567-million-kilometer) flight to Mars.

JPL, a division of the California Institute of Technology in Pasadena, manages the mission for the NASA Science Mission Directorate, Washington. More information about Curiosity is online at http://www.nasa.gov/msl.and http://mars.jpl.nasa.gov/msl/ . You can follow the mission on Facebook at: http://www.facebook.com/marscuriosity and on Twitter at: http://www.twitter.com/marscuriosity .

http://www.nasa.gov/mission_pages/msl/news/msl20120626.html

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How Curiosity Will Land on Mars, Part 2: Descent

In Part 1 of this series I took you through Curiosity's new guided-entry technology to a point still 11 kilometers' altitude. The next part of Entry, Descent, and Landing, usually abbreviated "EDL," is the descent, a two-minute period that will take the rover nearly all the way to the surface. Curiosity's descent can be split into two segments: parachute descent, and powered descent.

Parachute descent

The parachute descent phase lasts only 50 to 90 seconds (depending on atmospheric conditions). But during this brief time, according to this paper by the rover engineering team, "the parachute system acts to burn over 95% of the remaining kinetic energy.... In this short time descending under the parachute, the system undergoes a series of reconfigurations: jettisoning its heatshield, acquiring the Martian surface with onboard terminal descent sensor, and preparing the spacecraft to initiate powered descent."

When we last left our hero, it had descended to about 11,000 meters and decelerated to Mach 2.0 or roughly 450 meters per second. Slowing to that velocity -- still supersonic -- triggers the deployment of the parachute, which is only qualified up to Mach 2.2.

The parachute is enormous. Parachutes for Mars descent have not changed much since the Vikings landed; all have used what's called a disk-band-gap design, in which there is an open ring between the upper "disk" and lower "band," which increases the stability of the 'chute at supersonic speeds. However, Curiosity's parachute will be the largest ever opened on Mars, at 21.5 meters across, compared to Viking's 16.5 meters, Spirit and Opportunity's 14.1 meters, Pathfinder's 12.7 meters, and Phoenix' 11.8 meters. Remember this photo, which I consider one of the greatest pictures in the history of planetary exploration? Curiosity's is twice the size. And yes, Mars Reconnaissance Orbiter will try to repeat this photographic feat (more on that in a bit).

When the parachute first opens, it's likely to undergo "area oscillations," repeated snaps of the parachute from not-quite-open to open, events that place huge forces on the 'chute. These should disappear once the spacecraft has slowed to Mach 1.4.

Another concern after the parachute inflates is something called "wrist mode oscillations." This is where the spacecraft spins underneath the parachute. Here's an interesting sentence from Ravi's article: "Historical attempts to bound the wrist mode behavior and its time evolution following parachute deployment have failed to bound the behavior during flight (e.g. MER-B)." Translation: we're trying to figure out ways to make our computer simulations produce the same behavior we observe in reality, but we're not there yet. Without an understanding of why this oscillation happens, it's really hard to engineer a system that prevents it.

Instead, throughout the descent phase, Curiosity will use the little thrusters of its reaction control system to counteract these oscillations, bringing the spacecraft to a stable orientation.

If the huge parachute does its job, it will take less than 30 seconds to decelerate the spacecraft to subsonic speeds. Then, and only then, is it safe to drop off the heatshield that protected the rover throughout its fiery entry. Pyros will fire to unlock push-off springs that shove the heatshield downward and away from the spacecraft, exposing the wheels as well as the radar system that will sense the ground. Curiosity will wait five long seconds for enough distance -- 15 meters -- to develop between the heatshield and the rover before paying attention to the measurements from the range-finding "terminal descent sensor" (inevitably abbreviated "TDS"). This prevents the descent sensors from responding to reflections off of the heatshield, which will be a lot closer to Curiosity than Curiosity is to the ground!

The measurements from the rangefinding terminal descent sensor are absolutely critical to the timing of the rest of the landing events. But since Curiosity is not descending vertically, the altitudes that the terminal descent sensor are measuring are of spots at some distance away from the spot at which Curiosity will land. It could land as far as 700 meters away from the last range measurement it takes before its backshell separates. This is the reason that the Curiosity landing site has to be flat on several-hundred-meter length scales.

Another sensor that will be operating at this time is the Mars Descent Imager, whose photos will provide context for Curiosity's landing spot and help the science team figure out exactly where they are when they land.

So the terminal descent sensor is pinging away at the surface, providing continuous data on Curiosity's altitude, as it continues to descend and decelerate under parachute. The next step in the process comes when the spacecraft has slowed to about 80 meters per second, at an altitude somewhere around 1.5 kilometers. If all of this sounds rather approximate to you, it's not; there are 500,000 lines of code stored in Curiosity's electronic brains to handle every possible set of landing conditions, and the landing engineers have spent years poking and pushing at that code, throwing increasingly bizarre and challenging sets of conditions at it, including all kinds of bad-luck and low-probability failures of various components, to make sure it can handle every foreseeable contingency.

At 100 meters per second and 1500 to 2000 meters altitude, the spacecraft is ready to initiate the next step: powered descent. It prepares by opening the fuel lines to the 8 descent thrusters on its jetpack (otherwise known as the descent stage), and commanding them to 1% throttle.

Then comes what is, for me, the scariest moment in that landing animation. Pyros fire to separate the descent stage from the backshell and parachute. Suddenly lacking any means of slowing down, the spacecraft free-falls, accelerating toward the ground under Martian gravity for one heart-stopping second, speeding up from 100 to 120 meters per second. The one-second free-fall is necessary to ensure that the descent rockets don't slam the rover back into the backshell when they fire up. But: yikes.

Powered Descent

As the rover is free-falling, the rockets are already on. After that one second, they're throttled up. Still, the thrusters are not being used to decelerate the rover; at first, they are commanded to reduce any rotation of the spacecraft to zero as it continues to fall, accelerating slightly. Only when rotation has been damped, after about 400 meters of descent, do the thrusters power up to begin to slow the descent again.

At this point, the thrusters will smoothly operate to slow the spacecraft, completely halting its horizontal motion while bringing its vertical descent rate to 20 meters per second. This will take roughly 30 seconds, give or take, depending on the altitude at which the rover fell out of its backshell. Meanwhile, the backshell and parachute, equipped with no deceleration devices, will overshoot and crash ahead of the landing site.

The rover will calmly descend at 20 meters per second until its terminal descent sensors tell it that it has reached an altitude of 50 meters. Then the thrusters are throttled up again to decelerate the descent at a constant rate until it's reached a rate of 0.75 meters per second; it continues this descent rate for the rest of the landing. I paused at the moment after I wrote those words to get up from my chair and try to walk at that rate. It's about half my usual walking speed: very slow.

By the time it gets to an altitude of 21 meters, the descent stage will have burned through more than half of its 400 kilograms of fuel. If the rockets kept thrusting at a constant rate, they'd actually lift the rover upward. They have to be throttled back so much that they start to operate inefficiently. So four of the eight engines are shut down, allowing the four remaining engines to operate in a better zone (at around 50% of their full power). If you look at the artist's concept above, you'll notice that four of the engines are pointed straight down, and four are canted outward at an angle. The downward-pointing ones are shut down; the angled ones are left on. This prevents rocket exhaust from impinging on the rover after it is lowered from the backshell.

Under the four rockets, the rover waits for 2.5 seconds for any wobble induced by the switch from eight to four rockets to settle out. Then it's ready for the next phase: the Sky Crane.

Are you on the edge of your seat yet? That means it's a perfect time for me to say: tune in next week for the continuation of this multi-part drama!

But I did promise to talk about Mars Reconnaissance Orbiter HiRISE's planned attempt to image the spacecraft while it's descending under parachute. Curiosity's parachute will occupy about four times as many pixels as Phoenix' did, so it should be easier to spot. However, Mars Reconnaissance Orbiter's vantage point will not be as favorable for successful imaging. It looked at Phoenix from quite an oblique angle; it will be looking almost straight down at Curiosity. That leaves little room for error in the timing of the photo. The parachute is so big that it could be spotted easily in a Mars Reconnaissance Orbiter Context Camera photo, which has a much wider field of view than HiRISE. However, the Context Camera is not going to be commanded to make the attempt. If we get a picture of the spacecraft in midair, it will be from HiRISE.

One last thing: Some commenters on the first part of this series noticed I'd made a factual error. While in the guided entry phase, the aeroshell's blunt nose tips down, not up as I said before. I've corrected the other entry.

http://www.planetary.org/blogs/emily-lakdawalla/2012/06290700-how-curiosity-land-part-2.html

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Fireworks Over Mars - The Spirit of 76 Pyrotechnics

One month and a day after celebrating its independence with fireworks exhibitions throughout the country, America will carry its penchant for awe-inspiring aerial pyrotechnic displays to the skies of another world. Some pyrotechnics will be as small as the energy released by a box of matches. One packs the same oomph as a stick of TNT. Whether they be large or small, on the evening of August 5th (Pacific time), all 76 must work on cue as NASA's next Mars rover, Curiosity, carried by the Mars Science Laboratory, streaks through the Red Planet's atmosphere on its way to a landing at Gale Crater.

"We are definitely coming in with a bang -- or a series of them," said Pete Theisinger, Mars Science Laboratory project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "You only get one shot at a Mars landing, and the pyrotechnic charges we are using are great for reliably providing instantaneous, irreversible actions like deploying a parachute or opening a fuel valve."

Explosive pyrotechnic devices predate the space age by about a thousand years. Around 750 A.D., people in China began stuffing an early form of gunpowder into bamboo shoots and throwing them into a fire. At some point, someone interested in taking this new discovery to the next level (probably also from that region), decided aerial explosions would be even cooler, and the "aerial salute" was born. Fireworks were also part of America's very first Independence Day in 1777.

Pyrotechnics, or pyromechanical devices, are a natural but highly-engineered extension of these early fireworks. Instead of a rocket's red glare and bombs bursting in air, the energy from these explosions is contained within a mechanism, where it is used to move, cut, pull or separate something. Controlled explosions are a valuable tool to those who explore beyond Earth's atmosphere because they are quick and reliable.

"When we need valves to open, or things to move or come apart, we want to be confident they will do so within milliseconds of the time we plan for them to do so," said Rich Webster, a pyromechanical engineer at JPL. "With pyros, no electrical motors need to move. No latches need to be unlatched. We blow things apart -- scientifically."

Seventeen minutes before landing, the first 10 of 76 pyros will fire within five milliseconds of each other, releasing the cruise stage that provided the entry capsule (and its cocooned descent vehicle and the Curiosity rover) with power, communications and thermal control support during its 254-day journey to Mars.

"We have essentially three miniature guillotines onboard that, when the pyros fire, cut cabling and metal tubing that run between the cruise stage and the entry capsule," said Luke Dubord, avionics engineer for Mars Science Laboratory at JPL. "Then a retraction pyro pulls them out of the way. Along with that, we've got six pyrotechnic separation nuts, which when fired, will actually accomplish the separation."

One hundred and twenty-five milliseconds later, two more pyros fire, releasing compressed springs that jettison two 165-pounds(75-kilogram) solid tungsten weights. These weights allow the entry capsule to perform history's first planetary lifting body entry (see http://mars.jpl.nasa.gov/msl/mission/technology/insituexploration/edl/guidedentry/ ). A dozen minutes and one fiery, lifting-body atmospheric reentry later, another smaller set of tungsten weights is ejected by pyros to re-adjust the lander's center of mass for the final approach to the surface. A few seconds after that, the largest bang since the spacecraft separated from its Atlas rocket 254 days before is scheduled to occur.

"The Mars Science Lab parachute is the largest used on a planetary mission," said Dubord. "When folded up and in its canister, it's still as big as a trashcan. We have to get that folded-up chute out of its canister and unfolding in a hurry. The best way to do that is get it quickly away from spacecraft and out into the freestream using a mortar."

The best way to do that, the engineers at JPL decided, was to include a pyrotechnic charge equivalent to a stick of TNT.

"When something like this goes off, it makes a lot of noise" said Dubord. "Of course, at 8.7 miles [14 kilometers] up and a little over Mach 1, over Mars, I doubt anybody will be there to hear it."

While the ejection of the parachute is the biggest pyrotechnic display during the crucial entry, descent and landing, it is certainly not the last. The landing system needs to be released from the backshell that helped protect it during entry. The sky crane's descent engines need to be pressurized, and the rover itself needs to be released from the sky crane, where it is lowered on tethers toward the surface. All told, there are another 44 controlled explosions that need to happen at exactly the right time and at absolutely no other time for Curiosity to touch down safely at Gale Crater.

"Excluding the parachute mortar, the total 'explosive' material in all the pyrotechnics aboard the spacecraft is only about 50 to 60 grams," said Webster. "That is about the same amount of combustible material in the air bag in your car's steering wheel. When you do the math, the amount of explosive material in each pyrotechnic is only about what you would get out of a pack of matches.

"The thing is, a pack of matches won't help you land on Mars....pyrotechnics will," Webster added. The Mars Science Laboratory mission is managed by JPL for NASA's Science Mission Directorate in Washington. Curiosity was designed, developed and assembled at JPL. Caltech manages JPL for NASA.

A video about the challenges of the landing is online at: http://go.nasa.gov/Q4b35n or http://go.usa.gov/vMn .

Follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity http://www.twitter.com/marscuriosity

For more information on the Mars Science Laboratory/Curiosity mission, visit: http://www.nasa.gov/msl .

http://www.nasa.gov/mission_pages/msl/news/msl20120702.html

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How Curiosity Will Land on Mars, Part 3: Skycrane and landing

When we left our hero, Curiosity had traveled hundreds of millions of kilometers from Earth toward Mars, and had fewer than 20 meters left to go. She  will be descending at 0.75 meters per second toward the surface. Fewer than 15 seconds remain in her trip. It's time for the part of the mission that people seem to be the most scared about: the skycrane maneuver.

I want to begin by reviewing why something like the skycrane maneuver is necessary. There are two main reasons. First: Curiosity is huge, nearly five times the mass of Spirit or Opportunity. It's half again larger than a Viking lander. A Mars Exploration Rover weighs 185 kilograms; to get that 185 kilograms of rover safely to the ground required a protective enclosure of a lander weighing in at 348 kilograms.  Of all that 533 kilograms of landed mass, only 5 kilograms -- less than 1%! -- were science instruments.

Curiosity weighs 900 kilograms, of which 75 kilograms is science instruments. That's a much better proportion! But there is no way to wrap this thing in a lander large enough to protect it against an impact with the Martian surface. Instead, what you want to do is to go back to something more like Viking -- use a rocket-assisted descent -- except that Curiosity has to be able to drive away from the landing site, which means that the wheels have to serve in place of Viking's landing legs, and after the rover is on the ground you would really like to get the rockets and any remaining explosive fuel far away from your precious scientific exploration vehicle.

So: you need to set the rover down very gently, then sever the connection with the rockets and send them away, all without blasting the rover and its science instruments with rocket exhaust.

That's why skycrane is needed. There are five main steps in the skycrane maneuver: 1) separate the hard connection between the rocket-powered descent stage and the rover; 2) deploy the rover's landing gear (that is, its legs and wheels); 3) deposit the rover very gently on the surface; 4) sever the soft connection between the descent stage and the rover; and 5) fly the descent stage far away where its fuel can't do the rover and its instruments any harm, and won't contaminate the landing site.

Sky Crane

The first step in the Sky Crane maneuver is to separate the hard connection between the rover and the descent stage using pyros. Now all that remain are four connections: a triple bridle consisting of nylon cables, which bear all the weight, and an umbilical that supplies the electrical and electronic connections from the rover to the descent stage.

The three ropes come together at a "confluence point" underneath the descent stage, located near its center of mass; this design prevents differential loading on the bridle from tipping the descent stage. As soon as the hard connection between the rover and descent stage is severed, gravity carries the rover downward. The three ropes unwind together from an electromagnetically braked spool; it's the elecromagnetic brake that controls the rate of the rover's descent. Here's what that spool looks like; there's another view here.

I actually got a chance to hold some of that nylon cable in my hand. Someone from JPL's education department came to my daughter's school a few months ago and brought some toys she'd sweet-talked out of Curiosity's engineers: various small bits of spent test hardware. One of these was a bit of the nylon rope. It's a bit thicker than clothesline, but it still really looks and feels like clothesline. I'll be honest; it was a little surprising how slight that cable is. It's plenty strong, though.



She also brought a used pyro cutter of the sort that will slice through this nylon cord later. This was surprisingly heavy.



When the spool has unwound completely -- a process that takes seven seconds -- the rover will be suspended 7.5 meters beneath the descent stage, whose rockets are still firing. This is close enough that the descent rockets, which are canted outwards, will not impinge on the rover (even if the rover is unlucky enough to land on the side of a hill). But it completely separates the rocket-powered descender dynamically from the thing that it's landing.



The skycrane maneuver

In this artist's concept, Curiosity is in the final moments of its descent toward Mars, and is being lowered from the descent stage to the surface on three cables.

Reading that in the article on Curiosity's landing, I can almost hear the relief in the voice of the engineers that they don't have to deal with the jostling of the landing on the descent stage in the logic surrounding the timing of the next few events. If that didn't make sense, I'll put it another way: from an engineering standpoint, it's easier to land the rover safely and then get the rockets away from the rover with the rover dangling several meters below the rockets on strings. From that article:

Implementation of the Sky Crane architecture presents many advantages over historical touchdown methods, namely airbags and legged landers. The two-body architecture keeps the engines and thrusters away from the surface, mitigating surface interactions like dust excavation and trenching, while enabling closed loooped control throughout the touchdown event. The bridle decouples the touchdown event and associated disturbances from the descent stage controller. Additionally, rather than using a traditional touchdown sensor, touchdown is detected through a persistence of reduced throttle commands necessary to maintain the constant descent rate.

Due to the persistence of tethering during touchdown and low touchdown velocities, the system has greter touchdown stability and experiences lower impact loads than other landing systems. High stability and low loading, on par with rover driving loads, means that a separate touchdown system is not required and the egress phase can be eliminated. Rather, the rover's rocker-bogey suspension, which is specifically designed for surface interaction, is the touchdown system and it is properly positioned to begin operations immediately after touchdown.

As the spool plays out, the "landing gear" also come out, in two steps. They dangle too, waiting to meet the ground.

All this time (all 7 seconds!), the descent stage has continued to descend at a rate of 0.75 meters per second. When the last of the rope unwinds, it imparts a small jerk on the descent stage, and the spacecraft takes two seconds to wait for the rockets to compensate for that motion. After those two seconds, the rover starts expecting touchdown.



Curiosity touchdown!

In this scene, Curiosity has touched down onto the surface. The spacecraft has detected the touchdown, and pyrotechnic cutters have severed the connections between the rover and the spacecraft's descent stage.

Touchdown!

Curiosity pays close attention to the amount of force that the rockets must put out in order to continue the constant descent rate of 0.75 meters per second. When the ground is supporting the rover, that force will suddenly decrease. Curiosity will wait one second after that decrease -- an eternity, to a computer! -- checking to see if that decreased force remains constant, and checking also to make sure that the amount of force that the rockets are throwing out is consistent with the weight of the descent stage. When those criteria are met, the rover fires the pyros that free those metal guillotines that will cut the three ropes.

Remember that spool? It's got a spring in it, kind of like the one my old vacuum cleaner had. Without the weight of the rover pulling on the strings, they wind up -- zzzzzip! -- into the descent stage. At the same time, the rover transfers command of the descent stage up to the descent stage itself, and then cuts the electrical umbilical.

The descent stage holds a constant altitude for 187 milliseconds, allowing time for the umbilical to be cut, then throttles up the rockets, ascending vertically at first but then pitching to 45 degrees. Free of the rover's weight, the descent stage flies off. Originally, it was going to burn to depletion; but at some point they changed that plan, commanding it instead to burn for a fixed time. Then the rockets cut off, and the descent stage (and any remaining fuel) crash at least 150 meters away.

After that?

Silence.

Maybe a little creak or scrape here and there as the heavy load of the rover presses down on the rocker-bogie suspension system, which, in turn, presses down on Martian rocks and soil. Six wheels on Mars, at the moment of touchdown.

The rover won't immediately be able to get a panoramic view of its surroundings; its mast will still be folded flat to the deck, its seven mast-mounted eyes pressed into its back to prevent any dust thrown up by landing from settling onto the optics.

How will we know if it worked?

As these events play out, all three Mars orbiters will be listening to Curiosity broadcast from a sequence of UHF antennae -- first one on the aeroshell; after the parachute separates, the descent stage; after the descent stage flies off, the rover. The orbiters will be close enough to the rover to get fairly detailed information in this way. The venerable Mars Odyssey will provide -- as it did for Phoenix -- a "bent-pipe" relay, forwarding the data on to Earth as it receives it from the surface of Mars. (So I imagine that Odyssey's recent safing event, a result of a worn out reaction wheel, made Curiosity mission managers somewhat unhappy. Odyssey's back in action, on its backup reaction wheel.)

The other two orbiters, Mars Reconnaissance Orbiter and Mars Express, will record data for later transmission. Mars Reconnaissance Orbiter will also be trying to catch a view of Curiosity descending under its parachute. Here's a neat simulation of the relative positions of Mars Reconnaissance Orbiter and Curiosity as the landing happens, by Chris Laurel:



We'll also be able to hear Curiosity from Earth, though not with the high fidelity that the Mars orbiters will manage. On Earth, signals from the UHF antenna are so weak that we'll only get "semaphore codes" -- radio tones that match a prearranged code that indicate when such-and-such a step has been completed.

And then what?

And then we will have two rovers on Mars. Granted, it's possible that something in this process will fail and we will still just have Opportunity. I'm certainly nervous; landing a spacecraft on another planet is incredibly difficult, one of the crowning achievements of modern civilization, and it doesn't always work. Ultimately, though, I would much rather expect success, and be wrong, than predict failure, and be right.

I know how hard Curiosity's team has worked to get this rover to Mars. I know how smart they are, and how dedicated. We should be realistic: there are challenges here. But we wouldn't be trying to do this if we thought we couldn't succeed. And make no mistake: this is a gigantic "we," an entire country willing to support our greatest minds in the attempt of the most challenging goals.

So: I think we're going to do it. I can't wait for Sunday night, August 5, to hear the roar of the crowd I'm in, to see the engineers jump up and down, to imagine the thousands of people at Planetfest celebrating our collective achievement. We will land on Mars!

Go Curiosity!

http://www.planetary.org/blogs/emily-lakdawalla/2012/07060700-how-curiosity-land-part-3.html

[Salo]

http://lenta.ru/news/2012/07/06/marsradiation/

Российские ученые раскритиковали выбор места для посадки "Любопытства"[/size]
   
Российско-американская группа физиков оценила уровень ионизирующего излучения в разных слоях марсианского грунта и показала, что марсоход MSL "Любопытство" следует направить в кратер возрастом не более 10 миллионов лет. Свои выводы ученые представили на конференции и в статье для журнала Geophysical Research Letters. Содержание работы пересказывает сайт Американского геофизического союза.

Работа физиков была основана на моделировании разрушения органических веществ в марсианском грунте под действием космического ионизирующего излучения. В модели учитывался состав и структура грунта, изменения в составе атмосферы и уровне излучения на Марсе.

Моделирование показало, что обнаружение каких-либо органических веществ в двух верхних сантиметрах марсианской почвы практически невозможно. За последний миллиард лет своего существования этот слой поглотил, по словам авторов, около 500 миллионов грей ионизирующего излучения, что не могут выдержать даже простейшие органические молекулы.

Под верхним слоем находится слой глубиной от 5 до 10 сантиметров, поглотивший за время существования в десять раз меньше энергии - около 50 миллионов грей. Хотя такая доза по-прежнему не совместима с существованием сложных химических соединений, здесь возможно обнаружение простейшей органики вроде формальдегида или аминокислот.

Сложность заключается в том, что Марсианская научная лаборатория "Любопытство", которая направляется в данный момент к Красной планете, снабжена буром, способным сверлить на глубину лишь до 5 сантиметров. Исходя их результатов авторов, обнаружение органических веществ на такой глубине исчезающе маловероятно. Ученые считают, что аппарат нужно направить в молодые марсианские кратеры, где возраст осадков составляет не более 10 миллионов лет. По словам первого автора статьи, Александра Павлова, - "когда имеется возможность бурить, не нужно расходовать этот шанс на нетронутые области."

Тем не менее, на данный момент NASA по-прежнему планирует проводить августовское приземление "Любопытства" в пределах кратера Гейла. Его возраст составляет от 3,5 до 3,8 миллиардов лет. Имеются ли внутри него более мелкие молодые кратеры, пока не известно. Авторы надеются, что результаты их моделирования повлияют на решение NASA о выборе места бурения "Любопытством" или, хотя бы, марсоходами следующих поколений.[/size]

[Дмитрий Виницкий]

Послушать "российских физиков", так нет никаких признаков органических веществ в земной коре, ниже десятка метров
Откуда в мраморе, скажем, органика?


Не говорю, что собираются, прямо обнаруживать микро и макро окаменелости, но интерпретация наблюдений былых геохимических обстановок, для выяснения возможности существования условий для жизни на Марсе в прошлом. А поиском биологических следов должен заниматься гипотетический Astrobiology Field Laboratory (AFL)



Мля, новый мем рождается!

[m-s Gelezniak]

Послушать "российских физиков", так нет никаких признаков органических веществ в земной коре, ниже десятка метров
Откуда в мраморе, скажем, органика?


Не говорю, что собираются, прямо обнаруживать микро и макро окаменелости, но интерпретация наблюдений былых геохимических обстановок, для выяснения возможности существования условий для жизни на Марсе в прошлом. А поиском биологических следов должен заниматься гипотетический Astrobiology Field Laboratory (AFL)



Мля, новый мем рождается!

"Чёртик на верёвочке" :roll:

[ronatu]

Послушать "российских физиков", так нет никаких признаков органических веществ в земной коре, ниже десятка метров
Откуда в мраморе, скажем, органика?
...Не говорю, что собираются, прямо обнаруживать микро и макро окаменелости, но интерпретация наблюдений былых геохимических обстановок, для выяснения возможности существования условий для жизни на Марсе в прошлом. А поиском биологических следов должен заниматься гипотетический Astrobiology Field Laboratory (AFL)
...

Они про другое.
Про то что до 5 см глубины все будет УБИТО радиацией...

[m-s Gelezniak]

Послушать "российских физиков", так нет никаких признаков органических веществ в земной коре, ниже десятка метров
Откуда в мраморе, скажем, органика?
...Не говорю, что собираются, прямо обнаруживать микро и макро окаменелости, но интерпретация наблюдений былых геохимических обстановок, для выяснения возможности существования условий для жизни на Марсе в прошлом. А поиском биологических следов должен заниматься гипотетический Astrobiology Field Laboratory (AFL)
...

Они про другое.
Про то что до 5 см глубины все будет УБИТО радиацией...

Пусть ползёт на север. Они там...
"Ушёл зверь на дальний кордон. Точно говорю" (с) ОНО

[pkl]

Хм,  он может колесом грунт рыть, как современные роверы? Просто выбрать площадку и побуксовать на ней, сняв верхние 10 см грунта, а?

А Марс всё ближе:




 :roll:

[KBOB]

Чуть не забуксовал

[Старый]

Кстати, почему не делают колёса большего диаметра?

[Дмитрий Виницкий]

Про то что до 5 см глубины все будет УБИТО радиацией...

Что убито радиацией? Процесс седиментации и минералообразования?
Повторяю - MSL нацелен исследовать геохимические, а не биологические показатели. Никто никакой органики там искать не собирается.

[pkl]

Ну да, а газовый хроматограф с масс-спектрометром ему зачем?

Mars Curiosity descent from MRO
http://www.youtube.com/watch?v=-f0BDnJNW-8&feature=related

[pkl]

Кстати, почему не делают колёса большего диаметра?

Наверное, слишком здоровые колёса трудно спрятать под теплозащитный экран.