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Space News Update — May 19, 2015 —

Contents

In the News

Story 1:

Proton crash deals another blow to Russian space sector

Story 2:

Cause of galactic death: Strangulation

Story 3:

X-37B spaceplane to journey back into space Wednesday

Departments

The Night Sky

ISS Sighting Opportunities

NASA-TV Highlights

Space Calendar

Food for Thought

Space Image of the Week

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1. Proton crash deals another blow to Russian space sector

Failure struck Russia’s troubled space program for the second time in three weeks Saturday, when a Proton

rocket carrying a high-tech satellite for Mexico’s new $1.6 billion space-based communications network

crashed shortly after liftoff.

The 191-foot-tall Proton rocket launched at 0547:39 GMT (1:47:39 a.m. EDT; 11:47:39 a.m. local time) from

the Baikonur Cosmodrome in Kazakhstan, smoothly climbed through low clouds and disappeared from the

view of cameras at the arid Central Asia spaceport.

The first phase of the launch appeared to proceed according to plan, but something went wrong less than 10

minutes after liftoff.

A statement issued by Roscosmos — the Russian space agency — said an “emergency situation” occurred

during the launch, but the press release provided no further details.

Russian news reports said the Proton rocket’s third stage failed about eight-and-a-half minutes after liftoff, just

before the booster was programmed to disconnect from a Breeze M upper stage designed to guide the

Mexican government’s Mexsat 1 satellite into an orbit stretching more than 22,000 miles above Earth.

The state-owned Tass news agency reported the preliminary cause of the accident was in the steering engine

on the Proton’s third stage. A Russian space industry source quoted by Tass said the rocket likely fell back to

the ground from an altitude of 160 kilometers — about 100 miles — and burned up in the atmosphere.

Any debris that survived the high-speed descent probably fell in a region near Chita, a city in Siberia near

Russia’s southern border with Mongolia and China, according to Tass.

Space officials informed Russia’s Ministry of Emergency Situations of the crash site, Tass reported.

The Proton rocket’s third stage is powered by a single RD-0213 main engine producing 131,000 pounds of

thrust. A four-nozzle “vernier” engine on the third stage is designed to steer the rocket on the correct path

into space.

The rocket’s guidance, navigation and control system is a triple-redundant digital avionics package on the third

stage.

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International Launch Services, a Virginia-based firm overseeing Saturday’s commercial launch, confirmed the

failure in a statement a few hours after liftoff.

“Preliminary flight information indicates that the anomaly occurred during the operation of the third stage,

approximately 490 seconds after liftoff,” ILS said.

There were indications of trouble during a webcast of the launch, when an ILS program director providing

commentary on the flight was unable to confirm the completion of critical engine burns, blaming a disruption

in the flow of telemetry data from the rocket. The ILS manager claimed tracking information showed the

launch proceeding normally.

ILS is owned by Khrunichev State Research and Production Space Center, the builder of the Proton rocket and

Breeze M upper stage. The company is responsible for sales of Proton launch services on the commercial

market.

The launch mishap dealt another major blow to Russia’s space sector, happening as engineers were still

determining what doomed a Progress supply ship lost minutes after an April 28 launch with food, spare parts

and experiments for the International Space Station.

A different Progress freighter had to abort a planned reboost of the space station’s orbit Saturday, Roscosmos

said.

Saturday’s rocket crash occurred one year to the day after the last Proton launch failure, which destroyed a

Russian communications satellite after an anomaly in the booster’s third stage propulsion system.

An investigation into the May 2014 launch failure concluded the “probable cause of the failure was the loss of

structural integrity of a bolted interface that attaches the (third stage) steering engine turbopump to the main

engine structural frame,” ILS said in a statement released in September.

Officials did not disclose how engineers planned to resolve the structural problem on future launches, but the

ILS press release said in September that the “corrective action plan will adequately address the identified

probable cause and contributors to the failure.”

The Proton rocket flew successfully six times since the May 2014 mishap.

According to Tass, some type of third stage steering engine is the early focus of the investigation into

Saturday’s mission, which was the sixth failure of a Proton rocket or its Breeze M upper stage in 43 flights

since December 2010.

Before Saturday, the last Proton failure that destroyed a payload under the auspices of ILS came in 2007.

“ILS remains committed to providing reliable, timely launch services for all its customers,” the company said in

a statement after the failure. “To this end, ILS will work diligently with its partner Khrunichev to return Proton

to flight as soon as possible.”

Once a leader in the rocket business, ILS has seen its share of the commercial launch market erode in recent

years. The company announced its last firm contract win in January 2014, and commercial satellite owners

since then have awarded the bulk of launch service deals to Arianespace and SpaceX.

The Mexsat 1 satellite lost Saturday was supposed to help establish a mobile communications network to link

Mexican security forces, civilian authorities and remote outposts with 3G+ cellular voice and data services.

Built by Boeing in El Segundo, California, the 5.8-ton satellite — also dubbed Centenario in honor of the 100th

anniversary of the Mexican Revolution — was designed for a 15-year mission for Mexico’s Ministry of

Communications and Transportation.

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The Mexican government signed a $1 billion contract with Boeing in December 2010 for three satellites, two

ground stations and operations training. Mexico’s subsequent purchase of launch services put the Mexsat

program’s total cost near $1.6 billion.

The first of the three Mexsat relay stations — named Mexsat 3 or Bicentenario — launched on an Ariane 5

rocket in December 2012. Orbital ATK manufactured the satellite as a subcontractor to Boeing.

The last of the satellite trio — Morelos 3 — is nearly identical to the craft launched Saturday. It is scheduled to

launch as soon as October aboard an Atlas 5 rocket from Cape Canaveral.

Officials said Mexican troops, emergency responders, rural educators and hospitals will use the Mexsat

satellites for national security and humanitarian applications.

The next Proton launch was supposed to deploy a powerful communications satellite for London-based

Inmarsat in June, but Russian news reports said the rocket will be grounded while experts analyze the cause

of Saturday’s failure.

Source: Spaceflight Now Return to Contents

International Space Station Partners Adjust Spacecraft Schedule

NASA and its international partners agreed Tuesday to set a new schedule for spacecraft traffic to and from

the International Space Station.

The partner agencies agreed to adjust the schedule after hearing the Russian Federal Space Agency's

(Roscosmos) preliminary findings on the recent loss of the Progress 59 cargo craft. The exact dates have not

yet been established, but will be announced in the coming weeks. Roscosmos expects to provide an update

about the Progress 59 investigation on Friday, May 22.

The return to Earth for NASA's Terry Virts, ESA (European Space Agency) astronaut Samantha Cristoforetti and

Russian cosmonaut Anton Shkaplerov now is targeted for early June. NASA astronaut Scott Kelly and Russian

cosmonauts Mikhail Kornienko and Gennady Padalka will remain aboard the station to begin Expedition 44.

The next Russian cargo craft, Progress 60, will launch in early July to deliver several tons of food, fuel and

supplies. The space station has sufficient supplies to support crews until the fall of 2015.

The Soyuz spacecraft carrying Expedition 44’s Kjell Lindgren of NASA, Oleg Kononenko of Roscosmos, and

Kimiya Yui of the Japan Aerospace Exploration Agency, will launch in late July from the Baikonur Cosmodrome

in Kazakhstan.

The date of SpaceX’s seventh resupply flight under its commercial resupply services contract with NASA still is

under review but remains targeted for no earlier than June 19. The mission will deliver to station additional

supplies and research that improve life on Earth and drive progress toward future space exploration. It also

will deliver the first of two international docking adapters, which will enable future commercial crew vehicles to

dock to the orbiting laboratory.

Additional 2015 space station-related launch dates also are under review.

Source: NASA Return to Contents

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2. Cause of galactic death: Strangulation

Image Credit: re-active

As murder mysteries go, it's a big one: how do galaxies die and what kills them? A new study, published today

in the journal Nature, has found that the primary cause of galactic death is strangulation, which occurs after

galaxies are cut off from the raw materials needed to make new stars.

Researchers from the University of Cambridge and the Royal Observatory Edinburgh have found that levels of

metals contained in dead galaxies provide key 'fingerprints', making it possible to determine the cause of

death.

There are two types of galaxies in the Universe: roughly half are 'alive' galaxies which produce stars, and the

other half are 'dead' ones which don't. Alive galaxies such as our own Milky Way are rich in the cold gas -

mostly hydrogen - needed to produce new stars, while dead galaxies have very low supplies. What had been

unknown is what's responsible for killing the dead ones.

Astronomers have come up with two main hypotheses for galactic death: either the cold gas needed to

produce new stars is suddenly 'sucked' out of the galaxies by internal or external forces, or the supply of

incoming cold gas is somehow stopped, slowly strangling the galaxy to death over a prolonged period of time.

In order to get to the bottom of this mystery, the team used data from the Sloan Digital Sky Survey to analyse

metal levels in more than 26,000 average-sized galaxies located in our corner of the universe.

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"Metals are a powerful tracer of the history of star formation: the more stars that are formed by a galaxy, the

more metal content you'll see," said Dr Yingjie Peng of Cambridge's Cavendish Laboratory and Kavli Institute

of Cosmology, and the paper's lead author. "So looking at levels of metals in dead galaxies should be able to

tell us how they died."

If galaxies are killed by outflows suddenly pulling the cold gas out of the galaxies, then the metal content of a

dead galaxy should be the same as just before it died, as star formation would abruptly stop.

In the case of death by strangulation however, the metal content of the galaxy would keep rising and

eventually stop, as star formation could continue until the existing cold gas gets completely used up.

While it is not possible to analyse individual galaxies due to the massive timescales involved, by statistically

investigating the difference of metal content of alive and dead galaxies, the researchers were able to

determine the cause of death for most galaxies of average size.

"We found that for a given stellar mass, the metal content of a dead galaxy is significantly higher than a star-

forming galaxy of similar mass," said Professor Roberto Maiolino, co-author of the new study. "This isn't what

we'd expect to see in the case of sudden gas removal, but it is consistent with the strangulation scenario."

The researchers were then able to independently test their results by looking at the stellar age difference

between star-forming and dead galaxies, independent of metal levels, and found an average age difference of

four billion years - this is in agreement with the time it would take for a star-forming galaxy to be strangled to

death, as inferred from the metallicity analysis.

"This is the first conclusive evidence that galaxies are being strangled to death," said Peng. "What's next

though, is figuring out what's causing it. In essence, we know the cause of death, but we don't yet know who

the murderer is, although there are a few suspects."

Source: Eureka Alert Return to Contents

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3. X-37B spaceplane to journey back into space Wednesday

An experiment-carrying, reusable mini space shuttle operated by the

U.S. Air Force will be boosted into Earth orbit Wednesday atop a

United Launch Alliance Atlas 5 rocket.

It will be the fourth flight of the military’s X-37B program, also

known as Orbital Test Vehicle mission No. 4. The project is run

inside the Pentagon at the Rapid Capabilities Office.

Liftoff is scheduled for some time during a four-hour, unclassified

period that extends from 10:45 a.m. to 2:45 p.m. EDT (1445-1845

GMT) from Complex 41 at Cape Canaveral Air Force Station in

Florida. The actual target time will be announced on launch day.

Officials held a successful Launch Readiness Review on Monday

morning and gave approval for rollout of the rocket on Tuesday.

The weather outlook calls for a 60 percent chance of favorable

conditions.

The three previous X-37B missions over the past five years have

logged 1,368 days in space using a pair of spaceplanes that carried out their secret flights and then returned

to Earth to make pinpoint touchdowns on autopilot at Vandenberg Air Force Base in California.

Those three flights alone have eclipsed the NASA space shuttle cumulative duration of 1,334 days spent on

135 flights spread over 30 years.

“We are excited about our fourth X-37B mission,” said Randy Walden, the director of the Air Force Rapid

Capabilities Office. “With the demonstrated success of the first three missions, we’re able to shift our focus

from initial checkouts of the vehicle to testing of experimental payloads.”

The Air Force said it has collaborated with several partners to test new investigations on this fourth X-37B

flight.

The mission will check out the performance of an experimental electric propulsion system jointly developed by

the Air Force Research Laboratory and Space and Missile Systems Center. It is an in-space proof-testing of

design modifications for Hall Current Thrusters currently used on the military’s Advanced Extremely High

Frequency ultra-secure communications satellites.

The electric propulsion system produces a whisper-like thrust by ionizing and accelerating xenon gas. The fuel

economy is a distinct advantage of such systems over conventional chemical rockets, keeping the weight down

and enabling launch aboard a smaller, cheaper rocket.

“The experiment will include collection of telemetry from the Hall thruster operating in the space environment

as well as measurement of the thrust imparted on the vehicle. The resulting data will be used to validate and

improve Hall thruster and environmental modeling capabilities, which enhance the ability to extrapolate ground

test results to actual on-orbit performance,” the Air Force said.

There’s also a NASA advanced materials investigation aboard the X-37B.

Known as the Materials Exposure and Technology Innovation in Space, or METIS, the experiment will expose

nearly 100 different materials samples to the space environment.

METIS will fly a variety of quarter-sized samples of polymers, composites and coatings.

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One-quarter the size of NASA’s now-retired space shuttles, the robotic X-37B conducts its mission and then

autonomously returns to Earth, braking from orbit, plunging through the atmosphere and gliding to a landing

on a conventional runway to be refurbished and reused.

X-37B features a pickup truck-size cargo bay, seven feet long and four feet wide.

The craft’s unique capability to drop from orbit and land on a runway allows technicians to get their hands on

the hardware after being in space.

Built by Boeing’s Phantom Works division, the spaceplane is 29 feet long with a wing span of 15 feet, made of

light-weight composite structures instead of aluminum.

The craft is shielded with high-temperature wing leading-edge tiles made of toughened uni-piece fibrous

refractory oxidation-resistant ceramic, or TUFROC, instead of reinforced carbon-carbon panels used on NASA

shuttles. It also has a next-generation shuttle silica tile that’s more durable and toughened with uni-piece

fibrous insulation, and is the first space vehicle to use advanced conformal reusable insulation (CRI) blankets.

There are no hydraulics aboard the X-37B as flight controls and brakes use electromechanical actuation.

And unlike the space shuttles that used cryogenic liquid hydrogen and liquid oxygen reactants to generate

electricity through onboard fuel cells, limiting the mission lengths by the amount of consumables that could be

carried, the OTV is powered by a deployable solar array. The longest shuttle flight was 18 days.

The spaceplane can weigh up to 11,000 pounds fueled for launch.

This latest mission comes amid work to convert two former shuttle hangars at Kennedy Space Center over the

X-37B post-flight refurbishment halls. The Air Force won’t say if OTV 4 was readied for flight at KSC.

“OTV is leveraging previous space shuttle investments and the OPF facilities to conduct recovery and

refurbishment activities at a single location,” said Capt. Chris Hoyler, an Air Force spokesperson.

“Upon completion of the preparations at KSC, the program will have two landing options, one at KSC and one

at Vandenberg Air Force Base, California.”

The X-37B is shrouded inside the voluminous, 18-foot-diameter nose cone of the Atlas 5 rocket, which shields

it during atmospheric ascent.

The Atlas 5 is flying in its 501 configuration, a two-stage rocket with a five-meter payload fairing, no strap-on

boosters and a single-engine Centaur upper stage.

It is the 225th flight for the high-performance Centaur, which has launched spacecraft to every planet in the

solar system, plus the moon and Pluto.

Centaur stands 42 feet tall and weighs just 5,000 pounds, the pressure-stabilized, 0.20-inch thick stainless

steel walled balloon tanks hold 46,000 pounds of cryogenic liquid hydrogen and liquid oxygen fuel.

Three minutes and 45 seconds into the launch, the Atlas 5’s fairing will be jettisoned and expose the craft to

space. Staging occurs at four-and-a-half minutes and the Centaur upper stage executes a 13-minute burn to

heave the OTV spaceplane into low-Earth orbit. Deployment of the vehicle comes just shy of 19 minutes after

liftoff.

It will be the 54th Atlas 5 launch since 2002, the third this year and the program’s sixth use of the 501-

configuration. For ULA, this is its 96th mission overall since 2006, the 46th Atlas 5 to fly under the company’s

banner and fifth combined Atlas and Delta flight of the year.

Source: Spaceflight Now Return to Contents

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The Night Sky

Source: Sky and Telescope Return to Contents

Tuesday, May 19 Three doubles under Saturn. Once Saturn has risen well up in the southeast in late evening (see the illustration above), examine the little star 2° below it. That's Beta (β) Scorpii, a fine double star for telescopes. Another 1° below that is the very wide naked-eye pair Omega1 and Omega2 Scorpii, nearly vertical and a little too faint for the scene at the top of this page. Binoculars show their slight color difference. Left or lower left of Beta by 1.6° is Nu Scorpii, another fine telescopic double. High power in good seeing reveals Nu's brighter component itself to be a close binary, separation 2 arcseconds.

Wednesday, May 20

The waxing crescent Moon shines under Venus

this evening, in the feet of Gemini as shown

here. The brightest star in Gemini's feet is

Alhena, Gamma (γ) Geminorum; North

Americans can spot it not far to the Moon's left

or upper left.

Thursday, May 21

This evening the Moon shines between Venus

and Procyon. And Venus forms the bottom of a

tall V with Pollux and Castor; it's now 9° from

each.

Friday, May 22

Look below the waxing crescent Moon for

Procyon, the Little Dog Star. Right of the Moon

shines brilliant Venus with Pollux and Castor

over it.

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ISS Sighting Opportunities

Date Visible Max Height Appears Disappears

Tue May 19, 2:41 AM < 1 min 17° 17 above ENE 12 above ENE

Tue May 19, 4:13 AM 3 min 24° 15 above WNW 17 above NNE

Wed May 20, 3:22 AM 1 min 38° 38 above NNW 22 above NNE

Wed May 20, 4:58 AM 3 min 12° 10 above NW 10 above NNE

Thu May 21, 2:31 AM 1 min 23° 23 above NE 12 above NE

Thu May 21, 4:04 AM 3 min 15° 11 above NW 13 above N

Fri May 22, 3:12 AM 2 min 22° 21 above NW 17 above N

Fri May 22, 4:49 AM 1 min 10° 10 above NNW 10 above N

Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Time Zone)

1 p.m., Wednesday, May 20 - “STEM in 30”- Living and Working in Space -- Live from the Smithsonian’s

National Air and Space Museum (NTV-1 (Public), NTV-2 (Education))

6:45 a.m., Thursday, May 21 - Coverage of the Release of the SpaceX/Dragon Cargo Craft from the ISS (all

channels)

Watch NASA TV online by going to the NASA website. Return to Contents

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Space Calendar

May 19 - Garpun N2 Proton M/Briz M P3 Launch

May 19 - Comet 52P/Harrington-Abell At Opposition (2.789 AU)

May 19 - Asteroid 532 Herculina At Opposition (8.5 Magnitude)

May 19 - [May 16] Asteroid 2015 JO1 Near-Earth Flyby (0.066 AU)

May 19 - Asteroid 2015 HB117 Near-Earth Flyby (0.080 AU)

May 19 - [May 16] Asteroid 2015 JP1 Near-Earth Flyby (0.096 AU)

May 19 - Plutino 38628 Huya At Opposition (27.556 AU)

May 19 - 15th Anniversary (2000), STS-101 Launch (Space Shuttle Atlantis, SRTM)

May 19 - Francesco de Vico's 210th Birthday (1805)

May 20 - [May 19] X-37B OTV-4 (AFSPC 5)/ LightSail A Atlas 5 Launch

May 20 - Comet 19P/Borrelly Closest Approach To Earth (2.358 AU)

May 20 - Comet 293P/LINEAR At Opposition (2.741 AU)

May 20 - Comet 225P/LINEAR At Opposition (3.101 AU)

May 20 - Asteroid 58671 Diplodocus Closest Approach To Earth (1.419 AU)

May 20 - Asteroid 4716 Urey Closest Approach To Earth (2.351 AU)

May 20 - Plutino 2006 HJ123 At Opposition (34.042 AU)

May 20 - 15th Anniversary (2000), Galileo, Ganymede 28 Flyby

May 20 - George Bond's 190th Birthday (1825)

May 21 - [May 15] Dragon CRS-6 Return To Earth

May 21 - Comet 40P/Vaisala Closest Approach To Earth (1.630 AU)

May 21 - Comet 114P/Wiseman-Skiff At Opposition (3.877 AU)

May 21 - Asteroid 2015 HA1 Near-Earth Flyby (0.078 AU)

May 21 - Asteroid 1198 Atlantis Closest Approach To Earth (1.337 AU)

May 21 - Asteroid 268242 Pebble Closest Approach To Earth (1.348 AU)

May 21 - Asteroid 1997 Leverrier Closest Approach To Earth (1.362 AU)

May 22 - DirecTv 15/ Sky-Mexico 1 (SKYM 1) Ariane 5 Launch

May 22 - Comet P/1999 R1 (SOHO) At Opposition (1.172 AU)

May 22 - Comet 57P/du Toit-Neujmin-Delporte Perihelion (1.729 AU)

May 22 - Comet 57P-A/du Toit-Neujmin-Delporte Perihelion (1.729 AU)

May 22 - Comet P/2012 A3 (SOHO) At Opposition (2.322 AU)

May 22 - Comet P/2013 W1 (PANSTARRS) Closest Approach To Earth (2.874 AU)

May 22 - Comet 103P/Hartley At Opposition (4.163 AU)

May 22 - Asteroid 2011 WV4 Near-Earth Flyby (0.066 AU)

May 22 - Asteroid 6312 Robheinlein Closest Approach To Earth (1.319 AU)

May 22 - Asteroid 8952 ODAS Closest Approach To Earth (1.422 AU)

Source: JPL Space Calendar Return to Contents

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Food for Thought

Auroras on Mars

One day, when humans go to Mars, they might find that, occasionally, the Red Planet has green skies.

In late Dec. 2014, NASA's MAVEN spacecraft detected evidence of widespread auroras in Mars's northern

hemisphere. The "Christmas Lights," as researchers called them, circled the globe and descended so close to

the Martian equator that, if the lights had occurred on Earth, they would have been over places like Florida

and Texas.

"It really is amazing," says Nick Schneider who leads MAVEN's Imaging Ultraviolet Spectrograph (IUVS)

instrument team at the University of Colorado. "Auroras on Mars appear to be more wide ranging than we

ever imagined."

This isn't the first time a spacecraft has detected auroras on Mars. Ten years ago, the European Space

Agency's Mars Express found an ultraviolet glow coming from "magnetic umbrellas" in the southern

hemisphere.

Unlike Earth, Mars does not have a global magnetic field that envelops the entire planet. Instead, Mars has

umbrella-shaped magnetic fields that sprout out of the ground like mushrooms, here and there, but mainly in

the southern hemisphere. These umbrellas are remnants of an ancient global field that decayed billions of

years ago.

"The canopies of the patchwork umbrellas are where we expect to find Martian auroras," says Schneider. "But

MAVEN is seeing them outside these umbrellas, so this is something new."

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Auroras occur, both on Earth and Mars, when energetic particles from space rain down on the upper

atmosphere. On Earth, these particles are guided toward the poles by our planet's global magnetic field.

That's why auroras are seen most often around the Arctic and Antarctic. On Mars, there is no organized

planetary magnetic field to guide the particles north and south—so they can go anywhere.

"The particles seem to precipitate into the atmosphere anywhere they want," says Schneider. "Magnetic fields

in the solar wind drape across Mars, even into the atmosphere, and the charged particles just follow those

field lines down into the atmosphere."

According to the MAVEN data, solar particles that caused the "Christmas lights" penetrated deeply into the

Martian atmosphere---sparking auroras less than 100 km from the surface. That's lower than auroras on

Earth, which range from 100 km to 500 km high.

Like Mars Express 10 years ago, MAVEN has an ultraviolet camera, so it is not seeing the same thing as human

eyes. What would a human see?

Schneider isn't certain. "We’re still doing the physics," he says, "but we have some educated guesses."

Although the Martian atmosphere is primarily CO2, it does contain some oxygen--and that is key to the color

of the auroras. Excited oxygen atoms in the Martian atmosphere would likely produce green light.

"A diffuse green glow seems quite possible in the Mars sky, at least when the Sun is throwing off energetic

particles," says Schneider.

MAVEN arrived at Mars in Sept. 2014 on a mission to investigate a planetary mystery: Billions of years ago,

Mars was blanketed by layer of air massive enough to warm the planet and allow liquid water to flow on its

surface. Life could have thrived in such an environment. Today, however, only a tiny fraction of that ancient

air remains, leaving Mars a desiccated wasteland.

Where did the Martian atmosphere go? A favorite theory is solar wind erosion. Because Mars no longer has a

global magnetic field to protect it, solar wind might strip away material from the upper layers of the

atmosphere. Watching the auroras could help MAVEN mission scientists learn more about this process.

"Plus," says Schneider, who is looking forward to future data, "I just love auroras."

Source: NASA Return to Contents

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Space Image of the Week

Globular Star Cluster 47 Tuc Image Credit: NASA, ESA, Hubble Heritage Team (STScI / AURA) Acknowledgment: J. Mack (STScI) and G.

Piotto (U. Padova)

Explanation: Globular star cluster 47 Tucanae is a jewel box of the southern sky. Also known as NGC 104, it roams the halo of our Milky Way Galaxy along with over 150 other globular star clusters. The second brightest globular cluster (after Omega Centauri) as seen from planet Earth, 47 Tuc lies about 17,000 light-years away and can be spotted naked-eye near the Small Magellanic Cloud in the constellation of the Toucan. The dense cluster is made up of hundreds of thousands of stars in a volume only about 120 light-years across. Recent observations have shown that 47 Tuc's white dwarf stars are in the process of being gravitationally expelled to the outer parts of the cluster due to their relatively low mass. Other colorful low mass stars including yellowish red giant stars are easy to pick out on the outskirts of the cluster in this recently released sharp telescopic portrait by the Hubble Space Telescope.

Source: NASA Return to Contents