Asteroid Day: Rock on with your space self

June 29, 2017

Celebrate with a crash course on ASU’s NASA missions, meteorite collection and more

Planets get all the attention — just look at the ruckus raised when Pluto was demoted or anytime NASA announces exoplanet discoveries.

But on Friday, asteroids take center stage with their very own Asteroid Day, an annual event started in 2015 to commemorate the Tunguska eventThe Tunguska event was a large explosion above the Podkamennaya Tunguska River in Siberia on June 30, 1908, that flattened nearly 800 square miles of forest. The cause of the explosion is generally thought to have been a meteor that burst midair. .

There’s more to these space objects, however, than collisions and explosions. They also offer scientists a glimpse into the history of our solar system and may help us better understand the ground far beneath our feet.

NASA (where “every day is asteroid day,” according to its Facebook page) will be hosting a live chat about how researchers find and study near-Earth objects. It begins at 9 a.m. Arizona time Friday at facebook.com/NASAJPL.

Read on to learn about Arizona State University’s asteroid acumen, from NASA missions to meteorite know-how.

All Psyche-d up

The Psyche spacecraft is pictured in an artist rendering with a new high-power five-panel solar array. Image by Peter Rubin/ASU/SSL

Rock on … heavy metal … so many possible melodic puns, but let’s just stick to this one: It was music to ASU’s ears when NASA chose the university’s Psyche mission in January to be part of its Discovery Program.

The mission — the first time ASU is leading a deep-space NASA mission — will examine the metal asteroid Psyche, allowing scientists for the first time to see what is believed to be a planetary core.

The launch date was recently moved up one year to launch in the summer of 2022, with a planned arrival at the main asteroid belt in 2026 — four years earlier than the original time (some groovy mathIt’s not actually magic math. The revised trajectory is more efficient, as it eliminates the need for an Earth gravity assist, which ultimately shortens the cruise time. In addition, the new trajectory stays farther from the sun, reducing the amount of heat protection needed for the spacecraft. The trajectory will still include a Mars gravity assist in 2023. we wish we could apply to paying off our collector’s set of gold-plated Star Wars figurines).

Speaking of interplanetary economics, Psyche principal investigator and School of Earth and Space Exploration Director Lindy Elkins-Tanton said at a spring celebration of ASU space missions that Psyche contains metals worth 100,000 times the gross domestic product of Earth.

“One of these days we’ll be up there mining asteroids,” she said. “This is absolutely a precursor to commercial activity.”

Not to mention a good excuse to rewatch “Armageddon.”

Speaking of ‘Armageddon’ …

In the blockbuster film "Armageddon," an asteroid the size of Texas is on course to hit the Earth. NASA sends a crew of deep-core drillers to save the planet. Photo by Walt Disney Studios

How worried do we need to be about a Hollywood-blockbuster type of cosmic collision?

Not very. Laurence Garvie, research professor and curator for Arizona State University's Center for Meteorite Studies at the School of Earth and Space Exploration, has given public talks about asteroids, meteorites and the dangers they present here on Earth.

His message: You’re safe, basically.

Lots of space stuff falls on Earth — some 78,000 tons of it every year — but it’s mostly dust. And the majority of meteorites are only about a centimeter or so.

Chicxulub, which slammed into the Yucatan Peninsula, wiping out the dinosaurs and trashing the entire planet, is likely to occur only once every 100 million years.

We’ll all be fine.

Taking the solar system’s temperature

From left: Project principal investigator Phil Christensen, senior engineer William O'Donnell and lead engineer Greg Mehall pose with the OSIRIS-REx Thermal Emission Spectrometer (OTES), the first space instrument built entirely on ASU’s Tempe campus, on June 22, 2015. The OTES was launched in the OSIRIS-REx spacecraft in September 2016 on a mission to the asteroid Bennu. Photo by Charlie Leight/ASU Now

In the metro Phoenix area, we’ve been hyper aware of temperatures lately, watching the weather forecast for any bit of relief.

Regents’ Professor Phil Christensen is a temperature expert, but of a more outer-space kind. He’s the designer of thermal emission spectrometers on two separate NASA missions.

The first — the OSIRIS-REx Thermal Emission Spectrometer, or OTES to its friends — was the first space instrument built entirely on the ASU campus. After months of rigorous testing, it launched with the OSIRIS-REx spacecraft Sept. 8 on its way to a rendezvous with the asteroid Bennu.

OTES has several roles on the mission: determining the surface temperature and heat emission from all parts of Bennu at all times of day, and using long-wavelength infrared light to identify and map the asteroid’s minerals.

The second mission carrying a thermal emission spectrometer designed by Christensen will be the Lucy Mission, which will investigate Jupiter’s Trojan asteroids. The device will measure with great precision the surface temperatures on each asteroid the spacecraft visits. Doing so will help scientists decipher the asteroids’ histories.

Flight plans call for a 2021 launch for Lucy, which was named for the iconic fossil skeleton discovered by another ASU figure, paleoanthropologist Donald Johanson.

An asteroid by any other name …

Schoolchildren may know the mnemonic to remember the solar system planets in order: My Very Excellent Mother Just Served Us Nachos. But many might not realize that thousands of asteroids and minor planets revolving around our sun also have names (that would be one gnarly mnemonic, though we welcome anyone who wants to try to write it).

Having a namesake in the sky is no small honor, and at least 14 people• Erik Asphaug, School of Earth and Space Exploration (SESE) professor — Asteroid (7939) Asphaug • Jim Bell, SESE professor — Asteroid (8146) Jimbell • Robert Burnham, media relations manager, SESE — Asteroid (4153) Roburnham • Phil Christensen, SESE Regents’ Professor — Asteroid (90388) Philchristensen • Ernest Cisneros, SESE associate research professional — Asteroid (4643) Cisneros • Steven Desch, SESE professor — Asteroid (9926) Desch • Lindy Elkins-Tanton, Foundation Professor and SESE director — Asteroid (8252) Elkins-Tanton • Ronald Greeley, professor emeritus – Asteroid (30785) Greeley, and Greeley’s Haven (on Mars) • Donald Johanson, founding director of the Institute of Human Origins, Virginia M Ullman Chair in Human Origins in the School of Human Evolution and Social Change and the paleoanthropologist who discovered the “Lucy” fossil – Asteroid (52246) Donaldjohanson • Carleton Moore, SESE Regents’ Professor Emeritus – Asteroid (5046) Carletonmoore • Devin Schrader, SESE SESE assistant research professor – Asteroid (117581) Devinschrader • Sumner Starrfield, SESE Regents’ Professor – Asteroid (19208) Starrfield • Meenakshi Wadhwa, SESE professor and director of the Center for Meteorite Studies – Asteroid (8356) Wadhwa • Dave Williams, SESE associate research professor – Asteroid (10461) Dawilliams in the ASU community have received such an appellation accolade.

(And yes, one of them has the name Starrfield; we promise we’re not making that up.)

Space rocks here on Earth

Research Professor Laurence Garvie (left) examines a visitor's rock (which turned out not to be a meteorite) during the 2015 Earth and Space Exploration Day in Tempe. Photo by Deanna Dent/ASU Now

Some of the meteorites found on Earth come from the asteroid belt (and some from the moon or Mars), but with so many Earth rocks lying around, how do scientists tell the difference?

According to ASU’s Center for Meteorite Studies — which at 30,000-plus specimens has the world’s largest university-based meteorite collection — much of it has to do with age: Meteorites from the asteroid belt are far older than Earth rocks, which have been worn down and reformed repeatedly.

That’s how scientists can tell the difference. But how can the average person know?

Each fall, ASU hosts Earth and Space Exploration Day — as part of that, the public is invited to bring in what might be a meteorite for identification by Garvie. It’s a little bit like Antiques Roadshow, only with rocks; see a photo gallery here.

Users of the Sun Devil Rewards app can also collect “pitchforks” and cash them in for a tour of the ASU meteorite collection, among other ASU experiences and swag. Learn more here; the app is being relaunched in early July.

Top photo: Artist rendition of the asteroid Psyche. Image by Peter Rubin/ASU

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Roundabouts: Practical yet polarizing

Satellite images of roundabouts in Arizona

Traffic roundabouts are like broccoli. Many of us don’t like them, but they’re good for our driving diets.In the right conditions, they increase safety, lower crash severity, reduce traffic delays and can even reduce greenhouse gas emissions, says Mike Mamlouk, a professor of civil, environmental and sustainable engineering at Arizona State University’s Ira A. Fulton Schools of Engineering.B...

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Arizona Impact

Roundabouts: Practical yet polarizing

June 29, 2017

Roundabouts a contentious traffic feature in AZ, but an ASU professor found that they're safer, more efficient than traditional stops

Traffic roundabouts are like broccoli. Many of us don’t like them, but they’re good for our driving diets.

In the right conditions, they increase safety, lower crash severity, reduce traffic delays and can even reduce greenhouse gas emissions, says Mike Mamlouk, a professor of civil, environmental and sustainable engineering at Arizona State University’s Ira A. Fulton Schools of Engineering.

But despite their demonstrated safety in other states, they’re a highly polarizing traffic feature in Arizona, which is why Mamlouk decided to study their effects in the Grand Canyon State with former ASU graduate student Beshoy Souliman. Their research was funded by the National Transportation Center at Maryland, of which ASU is a consortium member.

Since modern roundabouts were first built in the United States in the 1990s, they’ve been constructed in most U.S. cities. In Arizona they began popping up more recently — in 2006. Today, the state has around 80 roundabouts, mostly in single-lane and some in double-lane configurations.

Mamlouk and Souliman studied 17 roundabouts in Phoenix, Scottsdale, Sedona, Cottonwood and Prescott to evaluate their effect on crashes and their severity.

They collected data on traffic volume and number and severity of accidents in an equal number of years before and after conversion from a stop sign or traffic signal to a roundabout. Additionally, they looked at crash severity and cost levels from damage only ($11,000 average) to fatality ($1.5 million average).

Modern roundabouts (left) are the newest traffic-control system on our roadways and smaller than older rotaries or traffic circles (right). Photo courtesy of Melissa Kay Photography, TripAdvisor

Stops vs. roundabouts

Intersections are dangerous places for drivers. Almost half of all traffic collisions in the United States happen at intersections.

Transportation engineers have found that if intersections are designed to be more forgiving — especially for distracted drivers who may run red lights or stop signs — they can minimize accidents or reduce accident severity when drivers make mistakes.

Roundabouts are one solution to this problem. In a roundabout, drivers are required to yield to cars already in the circle before they can merge, and raised lane splitters and medians help reduce traffic speed.

This configuration eliminates the potential for head-on and right-angle crashes.

“If a motorist runs the red light at a signalized intersection or does not stop at the stop sign, the vehicle will be on the path of crossing vehicles or opposing vehicles when making a left turn, which may result in a major accident,” Mamlouk said. “However, if a motorist enters the roundabout and does not yield to vehicles already in the circle, vehicles will crash at a small angle, causing a low-severity accident.”

Roundabouts have fewer dangerous conflict points, making accidents less likely to occur and less severe when they do occur. Graphic courtesy of Mike Mamlouk

Reduced traffic speed as drivers approach the roundabout intersection also reduces crash severity.

He added that the geometry of a roundabout means there are fewer conflicting points where crashes can occur. So in addition to reducing the severity of crashes, roundabouts reduce the chance of crashes.

Mamlouk and Souliman found that single-lane roundabouts decreased the total accident rate by 18 percent per year, and decreased the injury rate by 44 percent per year.

To Mamlouk’s surprise, two-lane roundabout accidents increased the total accident rate per year by 62 percent. However, these accidents were less severe and the injury rate decreased by 16 percent.

There was one fatality at a single-lane roundabout before conversion and one fatality at a double-lane roundabout before conversion. After roundabout conversions there were no fatalities for both single- and double-lane roundabouts. Also, the average accident cost per intersection decreased for both single- and double-lane roundabouts.

Constructing roundabouts in the right conditions

Though safety improved at the roundabouts the researchers studied, they are effective only in the right conditions, called warrants, which include levels of traffic volume, traffic fluctuation during the day, peak-hour factor, pedestrian volume, school crossing, crash experience and roadway network.

The Federal Highway Administration’s Manual on Uniform Traffic Control Devices lists warrants for various intersection control types, except roundabouts. Guidelines exist, but the decision is often more subjective than decisions to install stop signs or traffic lights.

“Although no warrants are currently available, engineers use the available guidelines together with previous experience to decide if a roundabout is suitable at an intersection,” Mamlouk said. “Warrants make the decision easier, consistent and more objective.”

When placed correctly, roundabouts also result in non-safety improvements for drivers.

“Instead of stopping at the stop sign or at the red light when no other vehicles are at the intersection, roundabouts allow motorists to proceed with caution without stopping, allowing for free-flow movement,” Mamlouk said. “Reducing stopping has the benefit of increasing the intersection capacity and reducing traffic delay and greenhouse gas emission.”

However, when poorly placed, roundabouts can cause increased traffic congestion and crash rates.

Warrants also help determine when a roundabout is no longer needed as traffic conditions change.

Educating the public

Professor Mike Mamlouk

As Mamlouk’s research concludes, he is presenting his findings to public officials to help them carefully assess the specific conditions at intersections before converting them to roundabouts.

As he and other researchers continue to observe and report on roundabout performance, warrants adhering to the Manual on Uniform Traffic Control Devices will begin to be developed.

Mamlouk also hopes to work with public agencies to help educate drivers about the proper use and advantages of roundabouts.

With only 80 roundabout intersections among the thousands of roadway intersections in the state, they’re still fairly rare, and using them correctly can take some practice

“When they introduced the traffic signals in the 1920s, it took people several years to get familiar with the three-color system and understand the rules of the traffic signal,” Mamlouk said. “I am sure people will get familiar with roundabouts with time and experience.”

Just as with the basics of using the traffic signal — now a no-brainer to alert drivers — the rules of the roundabout are simple:

“Remember, when getting close to a roundabout, slow down, look left, let vehicles already in the roundabout pass first, and then proceed with caution,” Mamlouk said.