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Space News Update — May 31, 2013 —

Contents

In the News

Story 1:

Data from NASA Rover's Voyage to Mars Aids Planning

Story 2:

NASA's Grail Mission Solves Mystery of Moon's Surface Gravity

Story 3:

Low Sodium Diet Key to Old Age for Stars

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. Data from NASA Rover's Voyage to Mars Aids Planning

Measurements taken by NASA's Mars Science Laboratory mission as it delivered the Curiosity rover to Mars in

2012 are providing NASA the information it needs to design systems to protect human explorers from radiation

exposure on deep-space expeditions in the future.

Curiosity's Radiation Assessment Detector (RAD) is the first instrument to measure the radiation environment

during a Mars cruise mission from inside a spacecraft that is similar to potential human exploration spacecraft.

The findings reduce uncertainty about the effectiveness of radiation shielding and provide vital information to

space mission designers who will need to build in protection for spacecraft occupants in the future.

"As this nation strives to reach an asteroid and Mars in our lifetimes, we're working to solve every puzzle nature

poses to keep astronauts safe so they can explore the unknown and return home," said William Gerstenmaier,

NASA's associate administrator for human exploration and operations in Washington. "We learn more about the

human body's ability to adapt to space every day aboard the International Space Station. As we build the Orion

spacecraft and Space Launch System rocket to carry and shelter us in deep space, we'll continue to make the

advances we need in life sciences to reduce risks for our explorers. Curiosity's RAD instrument is giving us

critical data we need so that we humans, like the rover, can dare mighty things to reach the Red Planet."

The findings, which are published in the May 31 edition of the journal Science, indicate radiation exposure for

human explorers could exceed NASA's career limit for astronauts if current propulsion systems are used.

Two forms of radiation pose potential health risks to astronauts in deep space. One is galactic cosmic rays

(GCRs), particles caused by supernova explosions and other high-energy events outside the solar system. The

other is solar energetic particles (SEPs) associated with solar flares and coronal mass ejections from the sun.

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Radiation exposure is measured in units of Sievert (Sv) or milliSievert (one one-thousandth Sv). Long-term

population studies have shown exposure to radiation increases a person's lifetime cancer risk. Exposure to a

dose of 1 Sv, accumulated over time, is associated with a five percent increase in risk for developing fatal

cancer.

NASA has established a three percent increased risk of fatal cancer as an acceptable career limit for its

astronauts currently operating in low-Earth orbit. The RAD data showed the Curiosity rover was exposed to an

average of 1.8 milliSieverts of GCR per day on its journey to Mars. Only about three percent of the radiation

dose was associated with solar particles because of a relatively quiet solar cycle and the shielding provided by

the spacecraft.

The RAD data will help inform current discussions in the United States' medical community, which is working

to establish exposure limits for deep-space explorers in the future.

"In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," said Cary

Zeitlin, a principal scientist at the Southwest Research Institute (SwRI) in San Antonio and lead author of the

paper on the findings. "Understanding the radiation environment inside a spacecraft carrying humans to Mars or

other deep space destinations is critical for planning future crewed missions."

Current spacecraft shield much more effectively against SEPs than GCRs. To protect against the comparatively

low energy of typical SEPs, astronauts might need to move into havens with extra shielding on a spacecraft or

on the Martian surface, or employ other countermeasures. GCRs tend to be highly energetic, highly penetrating

particles that are not stopped by the modest shielding provided by a typical spacecraft.

"Scientists need to validate theories and models with actual measurements, which RAD is now providing," said

Donald M. Hassler, a program director at SwRI and principal investigator of the RAD investigation. "These

measurements will be used to better understand how radiation travels through deep space and how it is affected

and changed by the spacecraft structure itself. The spacecraft protects somewhat against lower energy particles,

but others can propagate through the structure unchanged or break down into secondary particles."

After Curiosity landed on Mars in August, the RAD instrument continued operating, measuring the radiation

environment on the planet's surface. RAD data collected during Curiosity's science mission will continue to

inform plans to protect astronauts as NASA designs future missions to Mars in the coming decades.

SwRI, together with Christian Albrechts University in Kiel, Germany, built RAD with funding from NASA's

Human Exploration and Operations Mission Directorate and Germany's national aerospace research center,

Deutsches Zentrum für Luft- und Raumfahrt.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif.,

manages the Mars Science Laboratory Project and the project's Curiosity rover. The NASA Science Mission

Directorate at NASA Headquarters in Washington manages the Mars Exploration Program.

For more information about the mission, visit: http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl. To

follow the mission on Facebook and Twitter visit: http://www.facebook.com/marscuriosity and

http://www.twitter.com/marscuriosity.

For more information about NASA human spaceflight and exploration, visit: http://www.nasa.gov/exploration.

Source: NASA Return to Contents

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2. NASA's Grail Mission Solves Mystery of Moon's Surface Gravity

NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission has uncovered the origin of massive

invisible regions that make the moon's gravity uneven, a phenomenon that affects the operations of lunar-

orbiting spacecraft.

Because of GRAIL's findings, spacecraft on missions to other celestial bodies can navigate with greater

precision in the future. GRAIL's twin spacecraft studied the internal structure and composition of the moon in

unprecedented detail for nine months. They pinpointed the locations of large, dense regions called mass

concentrations, or mascons, which are characterized by strong gravitational pull. Mascons lurk beneath the

lunar surface and cannot be seen by normal optical cameras.

GRAIL scientists found the mascons by combining the gravity data from GRAIL with sophisticated computer

models of large asteroid impacts and known detail about the geologic evolution of the impact craters. The

findings are published in the May 30 edition of the journal Science.

"GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient

moon, when its interior was much hotter than it is now," said Jay Melosh, a GRAIL co-investigator at Purdue

University in West Lafayette, Ind., and lead author of the paper. "We believe the data from GRAIL show how

the moon's light crust and dense mantle combined with the shock of a large impact to create the distinctive

pattern of density anomalies that we recognize as mascons."

The origin of lunar mascons has been a mystery in planetary science since their discovery in 1968 by a team at

NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Researchers generally agree mascons resulted from

ancient impacts billions of years ago. It was not clear until now how much of the unseen excess mass resulted

from lava filling the crater or iron-rich mantle upwelling to the crust.

On a map of the moon's gravity field, a mascon appears in a target pattern. The bulls-eye has a gravity surplus.

It is surrounded by a ring with a gravity deficit. A ring with a gravity surplus surrounds the bulls-eye and the

inner ring. This pattern arises as a natural consequence of crater excavation, collapse and cooling following an

impact. The increase in density and gravitational pull at a mascon's bulls-eye is caused by lunar material melted

from the heat of a long-ago asteroid impact.

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"Knowing about mascons means we finally are beginning to understand the geologic consequences of large

impacts," Melosh said. "Our planet suffered similar impacts in its distant past, and understanding mascons may

teach us more about the ancient Earth, perhaps about how plate tectonics got started and what created the first

ore deposits."

This new understanding of lunar mascons also is expected to influence planetary geology well beyond that of

Earth and our nearest celestial neighbor.

"Mascons also have been identified in association with impact basins on Mars and Mercury," said GRAIL

principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "Understanding

them on the moon tells us how the largest impacts modified early planetary crusts."

Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a

nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their

mission ended in December 2012. The distance between the twin probes changed slightly as they flew over

areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses

hidden beneath the lunar surface.

JPL managed GRAIL for NASA's Science Mission Directorate in Washington. The mission was part of the

Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. NASA's Goddard

Space Flight Center, in Greenbelt, Md., manages the Lunar Reconnaissance Orbiter. Operations of the

spacecraft's laser altimeter, which provided supporting data used in this investigation, is led by the

Massachusetts Institute of Technology in Cambridge.

Lockheed Martin Space Systems in Denver built GRAIL.

For more information about GRAIL, visit: http://www.nasa.gov/grail

Source: Spaceref.com Return to Contents

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3. Low Sodium Diet Key to Old Age for Stars

Astronomers expect that stars like the Sun will blow off much of their atmospheres into space near the ends of

their lives. But new observations of a huge star cluster made using ESO's Very Large Telescope have shown -

against all expectations - that a majority of the stars studied simply did not get to this stage in their lives at all.

The international team found that the amount of sodium in the stars was a very strong predictor of how they

ended their lives.

The way in which stars evolve and end their lives was for many years considered to be well understood.

Detailed computer models predicted that stars of a similar mass to the Sun would have a period towards the

ends of their lives - called the asymptotic giant branch, or AGB [1] - when they undergo a final burst of nuclear

burning and puff off a lot of their mass in the form of gas and dust.

This expelled material [2] goes on to form the next generations of stars and this cycle of mass loss and rebirth is

vital to explain the evolving chemistry of the Universe. This process is also what provides the material required

for the formation of planets - and indeed even the ingredients for organic life.

But when Australian stellar theory expert Simon Campbell of the Monash University Centre for Astrophysics,

Melbourne, scoured old papers he found tantalising suggestions that some stars may somehow not follow the

rules and might skip the AGB phase entirely. He takes up the story:

"For a stellar modelling scientist this suggestion was crazy! All stars go through the AGB phase according to

our models. I double-checked all the old studies but found that this had not been properly investigated. I decided

to investigate myself, despite having little observational experience."

Campbell and his team used ESO's Very Large Telescope (VLT) to very carefully study the light coming from

stars in the globular star cluster NGC 6752 in the southern constellation of Pavo (The Peacock). This vast ball

of ancient stars contains both a first generation of stars and a second that formed somewhat later [3]. The two

generations can be distinguished by the amount of sodium they contain - something that the very high-quality

VLT data can be used to measure.

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"FLAMES, the multi-object high-resolution spectrograph on the VLT, was the only instrument that could allow

us to get really high-quality data for 130 stars at a time. And it allowed us to observe a large part of the globular

cluster in one go," adds Campbell.

The results were a surprise - all of the AGB stars in the study were first generation stars with low levels of

sodium and none of the higher-sodium second generation stars had become AGB stars at all. As many as 70%

of the stars were not undergoing the final nuclear burning and mass-loss phase [4] [5].

"It seems stars need to have a low-sodium "diet" to reach the AGB phase in their old age. This observation is

important for several reasons. These stars are the brightest stars in globular clusters - so there will be 70% fewer

of the brightest stars than theory predicts. It also means our computer models of stars are incomplete and must

be fixed!" concludes Campbell.

The team expects that similar results will be found for other star clusters and further observations are planned.

Notes

[1] AGB stars get their odd name because of their position on the Hertzsprung Russell diagram, a plot of the

brightnesses of stars against their colours.

[2] For a short period of time this ejected material is lit up by the strong ultraviolet radiation from the star and

creates a planetary nebula (see for instance eso1317).

[3] Although the stars in a globular cluster all formed at about the same time, it is now well established that

these systems are not as simple as they once thought to be. They usually contain two or more populations of

stars with different amounts of light chemical elements such as carbon, nitrogen and - crucially for this new

study - sodium.

[4] It is thought that stars which skip the AGB phase will evolve directly into helium white dwarf stars and

gradually cool down over many billions of years.

[5] It is not thought that the sodium itself is the cause of the different behaviour, but must be strongly linked to

the underlying cause - which remains mysterious.

For more information, see the ESO Press Release

Source: Spaceref.com Return to Contents

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The Night Sky

Friday, May 31

Mercury, Venus, and Jupiter have stretched out into a nice

straight line 7° long, as shown at right below. Look low in the

northwest after sunset. The line will continue to lengthen day by

day, as Jupiter descends to the horizon and Mercury pulls a bit

higher above Venus.

Last-quarter Moon (exact at 2:58 p.m. EDT). The Moon rises

around the middle of the night.

Saturday, June 1

Vega, the brightest star in the east these evenings, is currently the top

star of the huge Summer Triangle. Look to Vega's lower left, by two or

three fists at arm's length, for Deneb. The third star of the Summer

Triangle is Altair, considerably farther to Vega's lower right. Altair is

just rising in the east as dusk fades away. How early in the evening can

you spot it?

Sunday, June 2

The best time to view Venus in a telescope is in late afternoon well

before sunset, when it's still at a high altitude in relatively steady air.

Mercury and Jupiter are in the same vicinity, but they're tougher catches

in broad daylight. Pick them up them using the day-by-day finder chart

for all three above the afternoon Sun in the June Sky & Telescope, page

51.

Monday, June 3

"Cassiopeia" usually means "Cold!". Late fall and winter are when

this landmark constellation is high overhead (seen from mid-northern

latitudes), but even on hot June evenings it's lurking low. After dark,

look for it down near the north horizon. It's a wide, upright W. The farther north you are the higher it'll appear.

But even as far south as San Diego and Atlanta it's completely above the horizon.

Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver:

SATELLITE LOCAL DURATION MAX ELEV APPROACH DEPARTURE

DATE/TIME (MIN) (DEG) (DEG-DIR) (DEG-DIR)

ISS Sat Jun 01/00:26 AM < 1 31 14 above NNE 10 above NE

ISS Sat Jun 01/02:00 AM 1 11 10 above NNW 11 above NNW

ISS Sat Jun 01/03:38 AM < 1 12 10 above NNW 12 above N

ISS Sat Jun 01/11:38 PM < 1 50 10 above NE 10 above NE

ISS Sun Jun 02/01:11 AM 1 14 11 above NW 14 above NNW

ISS Sun Jun 02/02:49 AM < 1 11 10 above N 10 above N

ISS Sun Jun 02/04:25 AM 2 24 11 above NNW 23 above N

ISS Sun Jun 02/10:49 PM < 1 80 16 above NE 11 above NE

ISS Mon Jun 03/00:21 AM 4 17 11 above WNW 11 above NNE

ISS Mon Jun 03/02:00 AM < 1 10 10 above NNW 10 above NNW

ISS Mon Jun 03/03:36 AM 2 18 10 above NNW 17 above N

ISS Mon Jun 03/09:54 PM 6 46 11 above SSW 11 above ENE

ISS Mon Jun 03/11:31 PM 5 23 11 above W 11 above NNE

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

NASA-TV Highlights (all times Eastern Daylight Time)

May 31, Friday

8 a.m. - Replay of NASA Preview of the Approach of Asteroid 1998 QE2 - HQ (All Channels)

1 p.m. - Replay of NASA Preview of the Approach of Asteroid 1998 QE2 - HQ (All Channels)

Watch NASA TV on the Net by going to the NASA website.

Return to Contents

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Space Calendar

May 31 - O3b F-1, F-2, F-3 & F-4 Soyuz STB-Fregat Launch

May 31 - Cassini, Distant Flyby of Titan

May 31 - Comet 98P/Takamizawa Closest Approach To Earth (0.861 AU)

May 31 - [May 30] Asteroid 285263 (1998 QE2) Near-Earth Flyby (0.039 AU)

May 31 - Asteroid 3066 McFadden Closest Approach To Earth (1.677 AU)

May 31 - Asteroid 2906 Caltech Closest Approach To Earth (2.410 AU)

May 31 - Asteroid 2483 Guinevere Closest Approach To Earth (4.056 AU)

May 31 - 15th Anniversary (1998), Galileo, Europa 15 Flyby

Jun 01 - Comet P/2012 F5 (Gibbs) At Opposition (2.096 AU)

Jun 01 - Comet P/2004 V1 (Skiff) At Opposition (3.782 AU)

Jun 01 - Asteroid 2013 JU22 Near-Earth Flyby (0.052 AU)

Jun 01 - Asteroid 2011 BM45 Near-Earth Flyby (0.075 AU)

Jun 01 - Asteroid 2013 JT17 Near-Earth Flyby (0.098 AU)

Jun 01 - Asteroid 3173 McNaught Closest Approach To Earth (0.870 AU)

Jun 01 - Asteroid 5281 Lindstrom Closest Approach To Earth (2.235 AU)

Jun 01 - Asteroid 37452 Spirit Closest Approach To Earth (3.684 AU)

Jun 02 - Comet P/2012 F5 (Gibbs) Closest Approach To Earth (2.096 AU)

Jun 02 - Asteroid 19034 Santorini Closest Approach To Earth (3.836 AU)

Jun 02 - 10th Anniversary (2003), Mars Express/ Beagle 2 Launch

Jun 02 - 30th Anniversary (1983), Venera 15 Launch (USSR Venus Orbiter)

Jun 02 - 155th Anniversary (1858), Discovery of Donati's Comet

Jun 03 - SES-6 Proton M-Briz M Launch

Jun 03 - Comet C/2013 J6 (Catalina) Closest Approach To Earth (1.771 AU)

Jun 03 - Comet C/2012 OP (Siding Spring) At Opposition (3.050 AU)

Jun 03 - Comet 196P/Tichy At Opposition (3.651 AU)

Jun 03 - [May 27] Comet C/2013 H2 (Boattini) Closest Approach To Earth (6.670 AU)

Jun 03 - Asteroid 2004 KH17 Near-Earth Flyby (0.098 AU)

Jun 03 - Asteroid 8003 Kelvin Closest Approach To Earth (1.203 AU)

Painting of Donati’s Comet

Source: JPL Space Calendar

Return to Contents

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Food for Thought

Asteroid mining firm wants to put your face in space

A privately owned asteroid mining firm, backed in part by Google Inc's founders, launched a crowd-funding

project on Wednesday to gauge public interest in a small space telescope that could serve as a backdrop for

personal photographs, officials said.

Planetary Resources, based in Bellevue, Washington, plans to build and operate telescopes to hunt for asteroids

orbiting near Earth and robotic spacecraft to mine them for precious metals, water and other materials.

It also plans an educational and outreach program to let students, museums, armchair astronomers and virtual

travelers share use of a telescope through an initiative on Kickstarter, a website used to raise funds for creative

projects.

Planetary Resources aims to raise $1 million by June 30 to assess public appetite for participating in a space

project. It expects to launch its first telescope in 2015.

For a pledge of $25, participants can make use of a "space photo booth" by sending a picture to be displayed

like a billboard on the side of the telescope with Earth in the background. Its image would then be snapped by a

remote camera and transmitted back.

Starting at $200, participants can use the telescope to look at an astronomical object.

The Kickstarter campaign complements the company's ongoing efforts to design and build its first telescope,

called ARKYD. Investors include Google Chief Executive Larry Page and Chairman Eric Schmidt, as well as

Ross Perot Jr., chairman of the real estate development firm Hillwood and The Perot Group.

"All we are asking is for the public to tell us that they want something," company co-founder Eric Anderson

told reporters during a webcast press conference on Wednesday.

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"We're not going to spend our time and resources to do something if people don't want it and really the only

way to prove that it's something people want is to ask them for money," he said.

Planetary Resources is not the first space startup to turn to crowd-funding. Colorado-based Golden Spike, which

plans commercial human expeditions to the moon, has launched two initiatives on Indiegogo, another Internet-

based funding platform.

Golden Spike exceeded a $75,000 goal to start a sister firm, called Uwingu, designed to funnel profits into

space projects, but fell far short of a $240,000 target for spacesuits for Golden Spike's first moon run.

Hyper-V Technologies of Virginia turned to Kickstarter to raise nearly $73,000 to help develop a plasma jet

electric thruster. STAR Systems in Phoenix, Arizona, raised $20,000 for work on a hybrid rocket motor for its

suborbital Hermes spaceplane.

Last year, Washington-based LiftPort ended an $8,000 Kickstarter campaign with more than $100,000 to

demonstrate how robots could climb a 1.2-mile (2 km) long tether held aloft by a large helium balloon.

The company is working on an alternative space transportation system called a "space elevator" that uses tethers

or cables instead of rockets.

"I think crowd-funding is a new kind of bike and people are trying and willing to ride it, some successfully,

some not as successfully, but I think it's here to stay," said Golden Spike founder and planetary scientist Alan

Stern.

"These companies like Kickstarter and Indiegogo and RocketHub, they seem to be some kind of marketing

distribution system that lets people with an idea put it out there. Previously people didn't know how to do that

except run an ad in a newspaper. It's a capability we just didn't have five years ago," Stern said.

Source: Mineweb.com Return to Contents

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Space Image of the Week

One-Armed Spiral Galaxy NGC 4725

Explanation: While most spiral galaxies, including our own Milky Way, have two or more spiral arms, NGC

4725 has only one. In this sharp color composite image, the solo spira mirabilis seems to wind from a prominent

ring of bluish, newborn star clusters and red tinted star forming regions. The odd galaxy also sports obscuring

dust lanes a yellowish central bar structure composed of an older population of stars. NGC 4725 is over 100

thousand light-years across and lies 41 million light-years away in the well-groomed constellation Coma

Berenices. Computer simulations of the formation of single spiral arms suggest that they can be either leading

or trailing arms with respect to a galaxy's overall rotation. Also included in the frame, a more traditional looking

spiral appears as a smaller background galaxy

Image Data: Subaru Telescope (NAOJ), Hubble Space Telescope,

Additional Color data: Adam Block, Bob Franke, Maurice Toet - Assembly and Processing: Robert Gendler

Source: Astronomy Picture of the Day Return to Contents