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I want a dirigible that works like that 
By Pritzker Prize-winning designer Kazuyo Sejima
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Join & Support good comickers 
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The Rogue Blogger Who Keeps Spoiling Physics' Biggest News


On his physics-insider blog, Résonaances, theorist Adam Falkowski titled his latest post “After the Hangover.” He’s not talking about a party. He’s talking about particle physics—and the decline and fall of this year’s most-exciting-discovery-that-was-not.

On July 29, Falkowski declared what CERN, the European organization that runs the Large Hadron Collider, hasn’t yet: The Standard-Model-busting maybe-particle that has left physicists breathless since September actually isn’t busting anything. Because it’s not a particle. It’s just math, misbehaving. What appeared to be the signature of a brand-new thing was random fluctuations adding up in just the right way.

To make discoveries in particle physics, scientists have to accumulate lots of data. That data adds together, and tiny bumps that appear in the beginning can grow and gather significance. Or they can shrink. Particle physicists usually wait to declare a discovery until their results reach “five-sigma” confidence: If they did the same experiment 3.5 million times, they would see this result by chance just once.

But there’s a lot of lead-up to that five-sigma mark. And in that lead-up, physicists don’t just sit back in silence, wait, and wonder. They’re analyzing the data, theorizing about it. And gossiping about it—on Facebook, Twitter, blogs. Their murmurs usually make it into the wider world ahead of official announcements.

Within this physics rumor mill, the situation soon became clear: The LHC’s data was a fluke. But CERN wasn’t saying anything.

Falkowski thought people should know. So he decided to tell them ahead of schedule—“schedule” being a session and press event at the International Conference on High Energy Physics taking place in Chicago on Friday.

The Ghost Particle

Inside the Large Hadron Collider, physicists smash small particles together. These break apart, spreading subatomic debris and energy. Detectors catch the ultimate results of the collisions, and scientists work backwards to understand the particle chain that begat them. So far, physicists have only found particles predicted by the Standard Model, a framework developed in the 1970s. But this model has holes, and scientists are pretty sure it can’t be the whole story. They all cross their fingers that the LHC will discover something new, something that will confuse them and then lead them toward a more complicated understanding of the universe.

So they were thrilled when a December 15 presentation showed strange data from the LHC’s ATLAS and CMS detectors: an excess of photon pairs with energies of 750 gigaelectron-volts (GeV). They called it “the diphoton excess.” It wasn’t statistically significant, but it looked promising. It might have represented a particle six times more massive than the Higgs boson. Particle physicists got so psyched that they published 531 papers about it (isn’t that what you do when you’re psyched?). And they conversed.

“People talk,” says Falkowsi. They tweet. They send emails. Theorists are married to experimentalists, ergo particle-physics pillow talk. Falkowski says there is, in fact, a secret Facebook group that I am not allowed to join where physicists go precisely to discuss scientific rumors.

Falkowski watched his peers’ excitement, which mirrored his own. He published his own papers, and chronicled the saga on Résonaances, whose readership he estimates is 50 percent physicists. Previous posts on the same topic had the heds “Game of Thrones: 750 GeV edition” and “750 ways to leave your lover.”

The insider chatter started to become bleak, though, not long after the LHC started taking its first 2016 data in April. Different people brought different pieces of information to the secret group, and none of it looked good: The bump was disappearing. CERN stayed silent.

It’s been clear since June 20, Falkowski says, that the end was nigh. “And there’s a huge community out there, and they’re waiting for this result,” he says. On June 21, he tweeted:

Rumor: 750 GeV diphoton bump is going away as more data is collected by LHC. Most likely, excess seen in 2015 was just statistical fluke.

— Jester (@Resonaances) June 21, 2016

There were people around the world reading papers, writing papers, imagining the universe as it might be and what it would mean if it were. But Falkowski knew that these scientists were essentially writing anatomy articles about a jackalope.

“The fact that the experiment waits so long to announce this result, it doesn’t make any sense,” he says. “There is no really good reason for that.”

So on July 29, he pressed publish on a kind of obituary for the diphoton excess, making its death more than mere gossip. “We are currently going through the 5 stages of grief,” he wrote.

In the Beginning

Falkowski began Résonaances in 2007 when he was a postdoctoral researcher at CERN. He knew about the “blogosphere,” about sites like Sabine Hossenfelder’s Backreaction. “‘Why can’t I do it?’” he says he thought. “‘I’m at the center of the universe at CERN, so I could write something about what’s going on there.’”

It was winter, he thinks probably a rainy day, when he actually did it. “I had nothing else to do, so I just started writing,” he says. At the time, he was anonymous: Jester. Few people paid attention. But then his clicks started to creep up. “It was just a small thing for fun,” he says, “but it evolved into something more far-reaching than expected.”

Not quite far-reaching on the pop-level. His readers are serious about science’s specifics, whether they’re working physicists, former researchers, or autodidacts. He says he learns something new from 10 percent of the comments that come in.

I first came across his blog in 2014, when Falkowski wrote about flaws in an analysis of primordial gravitational waves. The BICEP2 team had just had a big-fanfare press conference on March 17, 2014, to announce their result—evidence of cosmic inflation, gravitational waves from the beginning of the universe. The words “Nobel Prize” were thrown around.

Falkowski wasn’t buying it.

He talked to lots of people who were in the field—outside his own area of expertise—to get a handle on their reservations and form his own. “I had to weigh the evidence and what I heard from people who were explaining what went wrong,” he says. Two months after the big press announcement, on May 12, he hit publish. Nature picked up on it.

Nine months later, in February 2015, the BICEP2 team made the statement themselves: Their analysis was flawed. “They had to bite the bullet,” Falkowski says. “They did this. They made the mistake. …They probably were unhappy with the way it was announced. But I never received any complaint from them about this story.”

Particle No More

By the time Falkowski was convinced the LHC’s diphoton bump was a ghost, lots of the physics community knew too. But others hadn’t yet heard, and without word from the inside, they couldn’t be sure. Falkowski doesn’t like the I-know-and-you-don’t of institutional holdback. “I think there is always a value in sharing information and in openness,” he says.

“People invest a lot of time and resources and energy into this,” he continues. “And I think if there is something obviously wrong, they should know.”

There are, of course, reasons that scientific organizations want to control the dissemination of information. It’s an attempt to ensure that the right information gets out, not just rumors; to stop premature data from leading people to incorrect conclusions. It’s also probably to get glory. But information will make itself free, one way or another, before press conferences. And sometimes the most well-planned announcements are the ones disseminating incorrect, or at least premature, conclusions.

For the most part, even though physicists knew of the disappearance of the diphotons early—and, a little later, so did people stalking around Twitter and science gossip blogs—people for the most part weren’t saying anything. Thursday afternoon, a day early, an abstract appeared on the CERN document server about the data surrounding goneness of the non-particle. While it initially contained the words “no significant excess,” the CMS collaboration removed those words. It seems CERN, the institution, isn’t so good at keeping its own secrets. Twitter noticed, but many journalists who had surely pre-written their articles still didn’t really call it until the official word came, at 10 am Eastern time today. We are all of us playing a weird game of chicken.

Even though this potential discovery didn’t pan out, Falkowski doesn’t think the time physicists spent on it was a waste. “I can perfectly imagine how this looks from the outside,” he says. “You have this rush of theorists who are writing 500 papers about nothing, something that disappears,” he says. “And there are some questions they have to ask themselves. But at the end of the day, one has to stress that no animal was hurt.”

Physicists saw something they couldn’t explain. They tried to explain it. And while the specifics of those explanations won’t make it into text- or history books, it’s likely every scientist who participated in the jackalope chase learned something. And the other option—putting data out of mind until there’s confirmation—would just slow down science. If the particle were actually a particle, physicists would have a pretty epic running start right now.

Still, Falkowski—and probably every particle physicist—is disappointed. He wanted to move beyond the Standard Model, and this seemed to be the shot. “But,” he clarifies, “the reason why I’m depressed is not because this particular bump went away but because it’s not clear we’ll get another chance. We badly need a discovery in our field to keep it moving. We’ve been waiting for so long, and it’s not coming.”

You can be sure, though, that if another chance does come, Falkowski will let you know.
Adam Falkowski keeps jumping the gun on the biggest announcements in physics. And he's doing it for a reason.
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Inspired by the work of René Magritte, award winning British artist Jake Phipps describes his 'Jeeves and Wooster' pendant, table and wall lights as 'a playful take on lighting with a real sense of cultural identity. The hat is an object that often associates its wearer with a particular so ...
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Found source of the quote - and it is still brainless hate speech


Donald Trump and Federal Indian Policy: ‘They Don’t Look Like Indians to Me’

In 1993, Donald Trump appeared before the United States House of Representatives Committee on Natural Resources to offer testimony on Indian gaming. 1993 Donald Trump bears a striking resemblance to Presidential Candidate Donald Trump, in terms of demeanor and language – Trump’s oral testimony is consistent with the language he has used throughout his campaign for President.

Most of Trump’s testimony focused on Indian gaming itself, and his perception that the Indian Gaming Regulatory Act granted tribes an unfair advantage over his own gaming enterprises.

But, it was another part of Trump’s testimony that caught my attention. He questioned the legitimacy of Indian tribes based upon the physical appearance of their members. Here is an exchange he had with Rep. Miller of California:

Mr. Miller. Is this you discussing Indian blood: “We are going to judge people by whether they have Indian blood,” whether they are qualified to run a gaming casino or not?

Mr. Trump. That probably is me, absolutely, because I’ll tell you what, if you look—if you look at some of the reservations that you have approved—you, sir, in your great wisdom, have approved— will tell you right now, they don’t look like Indians to me, and they don’t look like Indians. Now maybe we say politically correct or not politically correct. They don’t look like Indians to me, and they don’t look like Indians to Indians, and a lot of people are laughing at it, and you are telling how tough it is, how rough it is, to get approved. Well, you go up to Connecticut, and you look. Now, they don’t look like Indians to me, sir.

The written hearing records also include a transcript from his appearance on the Don Imus show earlier that same year:

Don Imus Show (June 18, 1993)

TRUMP: Well, I think I might have more Indian blood than a lot of the so-called Indians that are trying to open up the reservations.

I looked at one of them – well, I won’t go into the whole story, but I can tell you, I said to him, “I think I have more Indian blood in me than you have in you.” And he laughed at me and he sort of acknowledged that I was right. But it’s a joke. It’s really a joke.

IMUS: A couple of these Indians up in Connecticut look like Michael Jordan, frankly.

TRUMP: I think if you’ve ever been up there, you would truly say that these are not Indians. One of them was telling me his name is Chief Running Water Sitting Bull, and I said, “That’s a long name.” He said, “Well, just call me Ricky Sanders.” So this is one of the Indians.

You can see a video of Trump’s appearance before the Committee here. The transcript and hearing record is available here: 1993 Trump Nat Res Testimony PDF. (Trump’s testimony begins around Page 175). I recommend reading the entire portion of the record involving Trump, as it sheds light on his views on Indian gaming, tribal sovereignty, and the tax status of Indian tribes.

It is tempting to heap these comments onto the pile of other racist comments that Trump has made and be done with it.

But, Trump’s 1993 comments to the Natural Resources Committee highlight a problem that has plagued federal Indian law from the Indian Reorganization Act until today: the tension between the racial and political identity of Indian people.

Trump’s comments shed light on how a Trump Administration may implement its Indian policy, posing a real risk that the federal government will subordinate the sovereign status of Indian tribes to the racial identity of individual Indians. Such a policy would rely on a subjective evaluation of who is “Indian enough” in Trump’s estimation.

In the past, when the Federal government has focused on the racial identity of Indians (rather than our political identity), it has almost always been done to limit the Federal government’s trust obligations to Indians.

The Indian Reorganization Act and “Half-Blood” Indians

For nearly 160 years – from 1776 until 1934 – federal Indian policy could be fairly summarized this way: get rid of the Indians (through war or assimilation) and take their land.

In 1934, Congress enacted the Indian Reorganization Act, or the “IRA.” The IRA marked the beginning of modern federal Indian law, and at least recognized the right of Indian people to govern themselves into the future. Congress also understood that this would put the federal government on the hook for a continuing relationship with Indian tribes, and was forced to confront how to decide who were the “real Indians” and who were not.

On May 17, 1934, the United States Senate Committee on Indian Affairs debated the terms of the IRA. At issue in that debate was which Indians would be eligible to organize under the IRA and which Indians would be left out. Here is an exchange between Committee Chairman Burton Wheeler and Indian Affairs Commissioner John Collier during that debate:

The CHAIRMAN. There is a later provision in here I think covering that, and defining what an Indian is.

Commissioner COLLIER. This is more than one-fourth Indian blood.

The CHAIRMAN. That is just what I was coming to. As a matter of fact, you have got one-fourth in there. I think you should have more than one-fourth. I think it should be one-half. In other words, I do not think the Government of the United States should go out here and take a lot of Indians in that are quarter bloods and take them in under the provisions of this act. If they are Indians of the half-blood then the Government should perhaps take them in, but not unless they are. If you pass it to where they are quarter-blood Indians you are going to have all kinds of people coming in and claiming they are quarter-blood Indians and want to be put upon the Government rolls, and in my judgment it should not be done. What we are trying to do is get rid of the Indian problem rather than to add to it.

Senator Wheeler expressed concern that the IRA would be used by “white people” (his words) claiming to be Indian.

When the IRA was enacted into law one month later, it defined “Indian” as:

…all persons of Indian descent who are members of a recognized Indian tribe now under Federal jurisdiction, and all persons who are descendants of such members who were, on June 1, 1934, residing within the present boundaries of any Indian reservation, and shall further include all other persons of one-half or more Indian blood.

The Bureau of Indian Affairs and Indian tribes are still wrestling with this definition today – as seen in the Carcieri decision and the recent Mashpee litigation. The logical definition of “Indian” should have been simply, “all members of a recognized Indian tribe;” but, by adding time, residence and blood quantum limitations, Congress was seeking to evade its financial obligations and to constrain of the sovereign status of tribes.

Political Identity v. Racial Identity and Historic Tribes v. Created Tribes

In the 1970s, the BIA implemented a policy of “Indian preference” in employment – this applied to new employment, and opportunities for promotion within the BIA. Non-Indian employees of the BIA filed a class-action lawsuit alleging that this preference in employment was unconstitutional racial discrimination. The case – Morton v. Mancari – reached the U.S. Supreme Court in 1974. The Court upheld the BIA’s preference program, explaining that it was not racial discrimination. Instead, the Court stated that the preference was aimed at Indians as members of a political entity – similar to state-laws allowing state governments to grant employment preference to state residents:

Contrary to the characterization made by appellees, this preference does not constitute “racial discrimination.” Indeed, it is not even a “racial” preference. Rather, it is an employment criterion reasonably designed to further the cause of Indian self-government and to make the BIA more responsive to the needs of its constituent groups. It is directed to participation by the governed in the governing agency. The preference is similar in kind to the constitutional requirement that a United States Senator, when elected, be “an Inhabitant of that State for which he shall be chosen,” Art. I, § 3, cl. 3, or that a member of a city council reside within the city governed by the council. Congress has sought only to enable the BIA to draw more heavily from among the constituent group in staffing its projects, all of which, either directly or indirectly, affect the lives of tribal Indians.

At the same time as Morton v. Mancari, the Department of the Interior was drawing distinctions between Indian tribes based upon when and how they were recognized by the federal government. Attorneys within the Department’s Office of the Solicitor advanced the theory that some Indian tribes were “historic tribes,” because they have always maintained a relationship with the United States, while other tribes were “created” by the federal government. According to those attorneys, only “historic tribes” could exercise the full sovereign powers of Indian tribes, while “created tribes” had lesser sovereign powers.

Not surprisingly, the “historic tribes” included many of the Indian tribes that fit the romanticized ideal of Indians – tribes in the Great Plains and the Southwest (i.e. those tribes whose members “looked” like Indians). “Created” tribes were often those tribes whose members did not look like the Indians people saw in Hollywood westerns – people with lighter hair and eyes, or people with mixed Black or Mexican ancestry. This standard of “Indianness” ─ a Federal race-based standard ─ was again used to limit tribal sovereignty and contain the “Indian problem.”

The Department’s disparate treatment of “historic” and “created” tribes got so bad that Congress intervened, and enacted amendments to the IRA in 1994 to prevent the BIA from discriminating among tribes on this basis.

Trump and Indian Policy Today

Indian law today rests in large part upon the distinction between Indians as members of a racial/ethnic group, and Indians as citizens (a more accurate term than “members”) of sovereign political entities. This principle is foundational.

There are 567 federally recognized Indian tribes today, from southeast Florida to the north slope of Alaska. Some tribes’ citizens look like the idealized Indians from George Catlin paintings, while other tribes’ citizens would not “appear” to be Indian to a passerby on the streets of Washington, D.C. Despite the vast differences in their racial purity, every tribe maintains the right to determine its own rules for citizenship, to be governed according to its own laws, and to engage with the United States on a government-to-government basis.

But, there continue to be people who either don’t understand the distinction between the ethnic and political identities of Indian people, or who want to eliminate that distinction altogether.

In its recent decision in Adoptive Couple v. Baby Girl, the Supreme Court carved a hole in the Indian Child Welfare Act (which was enacted in 1978 to stop the epidemic of Indian children being taken from their families in Indian communities). In writing for the Court, Justice Alito left little doubt that the decision was premised on the Indianness of Baby Girl. Here is the first line of his opinion: “This case is about a little girl (Baby Girl) who is classified as an Indian because she is 1.2% (3/256) Cherokee.”

Last year, the Goldwater Institute in Arizona filed a lawsuit against the Department of the Interior seeking to overturn the entire Indian Child Welfare Act, arguing that the act unlawfully discriminates against Indian children on the basis of race. (The opening page of its complaint alleges, “Children with Indian ancestry, however, are still living in the era of Plessy v. Ferguson”).

The continuation of Indian tribes as sovereign governments in the United States depends, in large part, upon the distinction between Indians as a race of people, and Indians as citizens of Indian tribes. To blur or eliminate that distinction is to take an axe to the trunk of the tree of federal Indian law – federal laws applicable to Indians would be subject to the U.S. Constitution’s prohibition against racial discrimination.

Donald Trump’s most notable comments about Indian tribes – made before the Committee on Natural Resources – reveal that he does not draw the distinction between the racial and political identities of Indian people. His view of the legitimacy of Indian tribes depends on the physical appearance of their members. As he told Don Imus, “it’s just one of those things that we have to straighten out.”

A Trump Administration that acts upon that impulse will dramatically alter federal Indian policy as we know it.

This story was originally published on Turtle Talk on July 25, 2016.
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This TV movie had charm 
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Try as I might - I see nothing offensive here.


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My plan for 2017, this or the Daytona Coupe
Jarod and the crew from Snap-on Tools came by Factory Five recently to build an 818C! Check out part 1 of the build featured on their show “From the Ground …
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NASA's Mars 2020 Rover: New Landing Technique | JPL
The Mars 2020 rover mission has major new technologies that improve entry, descent, and landing (EDL): Range Trigger, Terrain-Relative Navigation, MEDLI2, and its EDL cameras and microphone.

Terrain-Relative Navigation helps us land safely on Mars—especially when the land below is full of hazards like steep slopes and large rocks!

HOW TERRAIN-RELATIVE NAVIGATION WORKS
Orbiters create a map of the landing site, including known hazards.
The rover stores this map in its computer "brain."
Descending on its parachute, the rover takes pictures of the fast approaching surface.

To figure out where it's headed, the rover quickly compares the landmarks it "sees" in the images to its onboard map.

If it's heading toward dangerous ground up to about 985 feet (300 meters) in diameter (about the size of two professional baseball fields side by side), the rover can change direction and divert itself toward safer ground.

WHY TERRAIN-RELATIVE NAVIGATION IS IMPORTANT
Terrain-Relative Navigation is critical for Mars exploration. Some of the most interesting places to explore lie in tricky terrain. These places have special rocks and soils that might preserve signs of past microbial life on Mars!

Until now, many of these potential landing sites have been off-limits. The risks of landing in challenging terrain were much too great. For past Mars missions, 99% of the potential landing area (the landing ellipse) had to be free of hazardous slopes and rocks to help ensure a safe landing. Using terrain relative navigation, the Mars 2020 rover can land in more—and more interesting!—landing sites with far less risk.

HOW TERRAIN-RELATIVE NAVIGATION IMPROVES ENTRY, DESCENT, & LANDING
Terrain-Relative Navigation significantly improves estimates of the rover's position relative to the ground. Improvements in accuracy have a lot to do with when the estimates are made.

In prior missions, the spacecraft carrying the rover estimated its location relative to the ground before entering the Martian atmosphere, as well as during entry, based on an initial guess from radiometric data provided through the Deep Space Network. That technique had an estimation error prior to EDL of about 0.6 - 1.2 miles (about 1-2 kilometers), which grows to about (2 - 3 kilometers) during entry.

Using Terrain-Relative Navigation, the Mars 2020 rover will estimates its location while descending through the Martian atmosphere on its parachute. That allows the rover to determine its position relative to the ground with an accuracy of about 200 feet (60 meters) or less.
It takes two things to reduce the risks of entry, descent, and landing: accurately knowing where the rover is headed and an ability to divert to a safer place when headed toward tricky terrain.

MEDLI2
IMPROVING MODELS OF THE MARTIAN ATMOSPHERE FOR ROBOTIC AND FUTURE HUMAN MISSIONS TO MARS.
MEDLI2 is a next-generation sensor suite for entry, descent, and landing (EDL). MEDLI2 collects temperature and pressure measurements on the heat shield and afterbody during EDL.
MEDLI2 is based on an instrument flown on NASA's Mars Science Laboratory (MSL) mission. MEDLI stands for "MSL Entry, Descent, and Landing Instrumentation." The original only collected data from the heat shield. MEDLI2 can collect data from the heat shield and from the afterbody as well.

This data helps engineers validate their models for designing future entry, descent, and landing systems. Entry, descent, and landing is one of the most challenging times in any landed Mars mission. Atmospheric data from MEDLI2 and MEDA, the rover's surface weather station, can help scientists and engineers understand atmospheric density and winds. The studies are critical for reducing risks to both robotic and future human missions to Mars.

ENTRY, DESCENT, AND LANDING (EDL) CAMERAS AND MICROPHONE
UNPRECEDENTED VISIBILITY INTO MARS LANDINGS
Mars 2020 has a suite of cameras that can help engineers understand what is happening during one of the riskiest parts of the mission: entry, descent, and landing. The Mars 2020 rover is based heavily on Curiosity's successful mission design, but Mars 2020 adds multiple descent cameras to the spacecraft design.

The camera suite includes: parachute "up look" cameras, a descent-stage "down look" camera, a rover "up look" camera, and a rover "down look" camera. The Mars 2020 EDL system also includes a microphone to capture sounds during EDL, such as the firing of descent engines.

A FIRST-PERSON VIEW OF LANDING ON MARS
In addition to providing engineering data, the cameras and microphone can be considered "public engagement payloads." They are likely to give people on Earth a good and dramatic sense of the ride down to the surface! Memorable videos depicting EDL's "Seven Minutes of Terror for the 2012 landing of NASA's Curiosity Mars rover went viral online, but used computer-generated animations. No one has ever seen a parachute opening in the Martian atmosphere, the rover being lowered down to the surface of Mars on a tether from its descent stage, the bridle between the two being cut, and the descent stage flying away after rover touchdown!

Engineering Constraints for Mars 2020 Mission Landing Site
Engineering constraints on potential 2020 landing sites are based on those derived for the MSL “sky crane” landing system, with some important exceptions.

Elevation:
Below -0.5 km MOLA elevation, with respect to the MOLA geoid.

Latitude:
Within ±30° of the equator./

Landing Ellipse:
Like MSL, the 2020 mission has a nominal landing ellipse of about 25 km by 20 km, oriented roughly east-west. A potential improvement under investigation, called range trigger, would allow landing within a 18 km long by 14 km wide ellipse. It may be possible in the future that the range trigger ellipse could become as small as 13 km by 7 km.

Terrain Relief and Slopes:
Less than ~100 m of relief at baseline lengths of 1-1,000 m to ensure proper control authority and fuel consumption during powered descent.
Less than 25°-30° slopes at length scales of 2-5 m to ensure stability and trafficability of the rover during and after landing.

Rocks:
The probability that a rock taller than 0.55 m high occurs in a random sampled area of 4 m2 (the area of the belly pan and area out to the inside of the wheels) should be less than 0.5% for the proposed sites. This corresponds broadly to 7% rock abundance, which is near the mode in the rock abundance for Mars as estimated from thermal differencing techniques. Subsequent analysis indicates the most critical area is just the belly pan of the rover, which covers ~2.7 m2 and can tolerate 0.6 m high rocks, which corresponds to about 12% rock abundance. Because rocks will eventually be counted in HiRISE images, rock abundance could locally be up to 20% provided that the overall risk for the ellipse does not exceed the 0.5% probability level.

Radar Reflectivity:
The Ka band radar backscatter cross-section must be > -20 dB and < +15 dB at Ka band to ensure proper measurement of altitude and velocity by the radar velocimeter/altimeter of the descent vehicle.
Load Bearing Surface:
Surfaces with thermal inertias greater than 100 J m-2 s-0.5 K-1 and albedo lower than 0.25 and radar reflectivities >0.01 to avoid surfaces dominated by dust that may have extremely low bulk density and may not be load bearing. Surfaces with thermal inertias less than ~150 J m-2 s-0.5 K-1 with high albedo may also be dusty and so should flagged for further investigation.

Credit: NASA's Jet Propulsion Laboratory

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#NASA #Astronomy #Space #Mars #Science #Mars2020 #Curiosity #MSL #Technology #Engineering #Wheels #Microphone #Sensors #Cameras #EDL #Entry #Descent #Landing #Exploration #Animation #GIF #Infographic #JPL #Pasadena #California #USA #UnitedStates 
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