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Space News Update — August 5, 2013 —
Contents
In the News
Story 1:
The Sun's Magnetic Field is about to Flip
Story 2:
Asteroid sampling mission to launch on Atlas 5 rocket
Story 3:
Bringing down the ISS – Plans for Station’s demise updated
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. The Sun's Magnetic Field is about to Flip
Something big is about to happen on the sun. According to measurements from NASA-supported
observatories, the sun's vast magnetic field is about to flip.
"It looks like we're no more than 3 to 4 months away from a complete field reversal," says solar physicist Todd
Hoeksema of Stanford University. "This change will have ripple effects throughout the solar system."
The sun's magnetic field changes polarity approximately every 11 years. It happens at the peak of each solar
cycle as the sun's inner magnetic dynamo re-organizes itself. The coming reversal will mark the midpoint of
Solar Cycle 24. Half of 'Solar Max' will be behind us, with half yet to come.
Hoeksema is the director of Stanford's Wilcox Solar Observatory, one of the few observatories in the world that
monitor the sun's polar magnetic fields. The poles are a herald of change. Just as Earth scientists watch our
planet's polar regions for signs of climate change, solar physicists do the same thing for the sun. Magnetograms
at Wilcox have been tracking the sun's polar magnetism since 1976, and they have recorded three grand
reversals—with a fourth in the offing.
Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun's polar magnetic fields
weaken, go to zero, and then emerge again with the opposite polarity. This is a regular part of the solar cycle."
A reversal of the sun's magnetic field is, literally, a big event. The domain of the sun's magnetic influence (also
known as the "heliosphere") extends billions of kilometers beyond Pluto. Changes to the field's polarity ripple
all the way out to the Voyager probes, on the doorstep of interstellar space.
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When solar physicists talk about solar field reversals, their conversation often centers on the "current sheet."
The current sheet is a sprawling surface jutting outward from the sun's equator where the sun's slowly-rotating
magnetic field induces an electrical current. The current itself is small, only one ten-billionth of an amp per
square meter (0.0000000001 amps/m2), but there‘s a lot of it: the amperage flows through a region 10,000 km
thick and billions of kilometers wide. Electrically speaking, the entire heliosphere is organized around this
enormous sheet.
During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a
baseball. As Earth orbits the sun, we dip in and out of the current sheet. Transitions from one side to another
can stir up stormy space weather around our planet.
Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova
explosions and other violent events in the galaxy. Cosmic rays are a danger to astronauts and space probes, and
some researchers say they might affect the cloudiness and climate of Earth. The current sheet acts as a barrier to
cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a
better shield against these energetic particles from deep space.
As the field reversal approaches, data from Wilcox show that the sun's two hemispheres are out of synch.
"The sun's north pole has already changed sign, while the south pole is racing to catch up," says Scherrer.
"Soon, however, both poles will be reversed, and the second half of Solar Max will be underway."
When that happens, Hoeksema and Scherrer will share the news with their colleagues and the public.
Source: NASA Return to Contents
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2. Asteroid sampling mission to launch on Atlas 5 rocket
A United Launch Alliance Atlas 5 rocket flying in its unique
configuration with a single strap-on solid booster mounted to the
first stage has been selected to send a NASA spacecraft to
rendezvous with an asteroid and return samples to Earth.
The Origins-Spectral Interpretation-Resource Identification-
Security-Regolith Explorer (OSIRIS-REx) spacecraft is
scheduled for launch in September 2016 from Cape Canaveral,
Florida.
Known as the 411 version of the Atlas 5, the launcher will
feature one solid rocket booster, the kerosene-fueled main stage,
a cryogenic Centaur upper stage and a four-meter-diameter nose cone.
The configuration has flown three times to date, all successfully, since 2006, deploying a commercial European
TV satellite and a pair of classified National Reconnaissance Office missions.
The Atlas design allows planners to tailor the rocket to exact needs of a payload, adding solid motors for greater
liftoff power and various nose cone sizes to enclose the cargo.
"With 39 successful missions spanning a decade of operational service, the commercially developed Atlas 5 is
uniquely qualified to provide launch services for these high-value NASA New Frontier Missions," said Jim
Sponnick, ULA vice president of Atlas and Delta Programs. "Atlas 5 is currently the only launch vehicle
certified by NASA to fly the nation's most complex exploration missions."
Atlas 5 launched for NASA nine times, including two payloads earlier this year -- the TDRS K communications
satellite and the new Landsat. It is slated to send the agency's MAVEN spacecraft to Mars in November and
another TDRS in January.
OSIRIS-REx, equipped with high-resolution cameras, LIDAR and spectrographs, will cruise to the near-Earth
asteroid 101955 Bennu, arriving in October 2018 for a 505-day survey to determine the massive space rock's
composition, chemical makeup and the best spot for sampling.
Approaching at a pace of 3.9 inches per second, the spacecraft will extend a robotic arm to reach the asteroid's
surface, capturing rocks and soil stirred up by blasting nitrogen gas at the surface in a "touch-and-go" maneuver.
The samples will be stowed in a return capsule and brought back to Earth in September 2023 for a parachute-
assisted touchdown.
Asteroid 101955 Bennu orbits the sun every 1.2 years on a path that comes close to Earth every six years.
Precisely measuring its orbit is seen as critical since recent calculations resulted a 1 in 1,800 chance of impact
with Earth in 2182.
Samples collected by the mission will be taken to the Johnson Space Center's curation facility for world-wide
distribution and scientific analysis.
Source: Spaceflight Now Return to Contents
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3. Bringing down the ISS – Plans for Station’s demise updated
The latest meeting of NASA‘s Aerospace Safety
Advisory Panel (ASAP) was briefed on an updated
action plan pertaining to the End Of Life (EOL)
scenario for the International Space Station (ISS). The
plan for a destructive deorbit of the Station is required
in the event of a serious contingency resulting in the
evacuation of the crew.
The orbital outpost is currently set to continue flying
until at least 2020, although ongoing studies are being
used to evaluate how long the ISS can continue to
perform its duties, especially from the standpoint of
the hardware‘s long-term health.
At present, it is hoped the ISS could continue to
operate until at least 2028, pending political and international agreement on the operational requirements and
running costs.
Providing the ISS continues to be mechanically healthy, opting against an extension would be close to
unthinkable.
The Station took decades and billions of dollars to assemble, providing the Space Shuttle fleet with their final
major role ahead of retirement – completing assembly and allowing for the transition to the utilization phase.
With the ISS permanently crewed by up to six international expedition members, resupply ships from Russia,
Europe and Japan take it in turns to restock the Station with vital supplies, while the Russian Soyuz provides the
task of crew rotations.
This fleet of ―Visiting Vehicles‖ has since been joined by the first commercial spacecraft from the United
States, with SpaceX‘s Dragon currently preparing for its fourth visit during CRS-3 (SpX-3) at the end of this
year. Orbital‘s Cygnus spacecraft is also expected to make its first trip to the ISS this summer, ahead of
initiating its Commercial Resupply Services contract obligations.
Commercial space companies are also primed to remove the United States‘ dependence on the Russian Soyuz as
a means of lofting NASA astronauts to the Station.
America‘s domestic launch and crew transportation capability was lost when Atlantis closed out the Space
Shuttle Program (SSP) at the conclusion of STS-135. And, with the aborted Constellation Program (CxP)
failing to allow Orion to take up the role before the middle of this decade, NASA created the Commercial Crew
Program (CCP).
With hundreds of millions of NASA dollars aiding the development of three commercial spacecraft options, the
first ―United States Crew Vehicle‖ (USCV-1) flight is currently manifested for late 2017.
Should the ISS be abandoned in 2020, no more than six USCV missions will have taken place – with the final
flight (USCV-6) supporting the last Expedition to iconic laboratory – per the latest long-term manifest
available.
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However, the death of the ISS isn‘t restricted to hardware health or political meddling, it also has to deal with
the inherent risks of flying in space, which forever threaten a contingency scenario.
While the Station is protected against major contingencies via teams of expert engineers on the ground, along
with techniques in space – such as the Debris Avoidance Manuever (DAM) that allows the ISS to move out of
the way of space debris – NASA managers always have to consider the worst case scenarios.
Almost all contingency events should still result in the crew surviving, with two Soyuz spacecraft ready to
provide the role of lifeboats in the event of an evacuation being called. However, a painful decision would then
be required over the fate of the Station itself.
ISS Program manager Mike Suffredini recently briefed the ASAP on such plans at the Marshall Space Flight
Center (MSFC), describing the latest evaluations on what would be an EOL scenario for the Station.
―NASA now has a plan so that in the event the Station must be evacuated, there will be a 14-day period in
which to make a decision on whether or not to bring the ISS down. The Program is setting the contingency plan
in place, although there is still a lot of work to be done,‖ noted the minutes from the meeting.
Previous plans have noted that NASA‘s initial response would be to plan to raise the Station‘s orbit, buying
them potentially years to work out what to do with the abandoned spacecraft – hypothetically allowing for a
potential repair or some form of orbital salvage operation.
However, based on the scenario where the ISS was dying, a controlled deborbit plan is preferred, aided by two
final Visiting Vehicles.
―They will have 180 days to get down to deorbit altitude. This would give them time to get two Russian
Progress vehicles launched to autonomously dock, autonomously transfer propellant to the Service Module, and
to provide propulsion to deorbit. This would provide a good, safe, controlled deorbit.‖
Although the disposal corridor over an uninhabited ocean expanse would be refined nearer the time, the deorbit
and destructive re-entry of the Station would be by far the largest man-made object to make the fiery plunge
back to Earth. A large amount of hardware would likely survive re-entry.
The use of two Progress vehicles is also the current method of execution for the Station per its natural EOL.
―In the past, proposals for using Progress to provide impulse to de-orbit had been discussed,‖ noted a previous
ISS Program overview to the ASAP. ―The Program is developing plans for a single Progress, which would be
used for off-nominal EOL; for the planned EOL, there would be two Progress vehicles that would provide more
impulse and better targeting to hit the impact point.‖
The ASAP noted they are ―very pleased‖ with the progress being made on the EOL scenarios.
―The ASAP raised this issue two or three years ago as the kind of thing to think about ahead of time,‖ added the
minutes. ―At that time, the general thinking was that the response would be to boost the orbit to get the Station
higher; however, after all the analysis was done, it was determined that what will actually be needed is the
opposite.
―The ASAP is pleased that all of this work has been done in advance.‖
Source: NASASpaceflight.com Return to Contents
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The Night Sky
Source: Sky & Telescope Return to Contents
Friday, August 9
Early in twilight, about a half hour after sunset, look very low in the west below Venus for the thin crescent
Moon, as shown at right. Binoculars will help.
The Perseid meteor shower is ramping up! Activity is already well under way, and the shower should peak late
Sunday and Monday nights. Read all about it: Get Ready for the 2013 Perseids.
Saturday, August 10
The waxing crescent Moon shines well to the left of Venus low in twilight, as shown above.
Sunday, August 11
The annual Perseid meteor shower should be at its most active late tonight and tomorrow night. (The expected
peak time, 2 p.m. EDT August 12th, is ideal for the Far East; for North America it splits the difference between
the early morning hours of the 12th and 13th.) See our article Get Ready for the 2013 Perseids.
Monday, August 12
During and after dusk, spot Saturn above the waxing crescent Moon in the southwest. Look lower right of the
Moon for Spica. Much higher to their upper right shines Arcturus.
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ISS Sighting Opportunities For Denver:
Date Visible Max Height Appears Disappears
Fri Aug 9, 9:25 PM 2 min 19° 19 above NNW 11 above NNE
Fri Aug 9, 11:02 PM 1 min 10° 10 above N 10 above NNE
Sat Aug 10, 8:36 PM 3 min 25° 25 above NNW 11 above NNE
Sat Aug 10, 10:13 PM 1 min 11° 11 above N 10 above NNE
Sun Aug 11, 9:24 PM 2 min 12° 12 above NNW 10 above NNE
Sun Aug 11, 11:02 PM 1 min 12° 11 above N 12 above N
Mon Aug 12, 8:35 PM 2 min 15° 15 above NNW 10 above NNE
Mon Aug 12, 10:13 PM 2 min 11° 10 above N 10 above NNE
Sighting information for other cities can be found at NASA‘s Satellite Sighting Information
NASA-TV Highlights (all times Eastern Daylight Time)
August 9, Friday
9 a.m. - Coverage of the Berthing of the ―Kounotori‖ HTV-4 Cargo Vehicle to the ISS (Installation scheduled
to begin around 9:30 a.m. ET) - JSC (All Channels)
1 p.m. - NASA Google+ Hangout: Wildfire and Climate Change - GSFC (All Channels)
Watch NASA TV online by going to the NASA website. Return to Contents
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Space Calendar
Aug 09 - Asteroid 277475 (2005 WK4) Near-Earth Flyby (0.021 AU)
Aug 10 - Asteroid 9997 COBE Closest Approach To Earth (1.611 AU)
Aug 10 - Asteroid 4523 MIT Closest Approach To Earth (2.015 AU)
Aug 11 - Comet C/2013 N4 (Borisov) Closest Approach To Earth (2.055 AU)
Aug 11 - Comet P/2011 JB15 (Spacewatch-Boattini) At Opposition (4.549 AU)
Aug 11 - Asteroid 16421 Roadrunner Closest Approach To Earth (1.013 AU)
Aug 11 - Asteroid 12790 Cernan Closest Approach To Earth (1.341 AU)
Aug 11 - Asteroid 6143 Pythagoras Closest Approach To Earth (1.650 AU)
Aug 11 - Asteroid 3125 Hay Closest Approach To Earth (2.107 AU)
Aug 11 - Asteroid 4969 Lawrence Closest Approach To Earth (2.283 AU)
Aug 12 - Comet 152P/Helin-Lawrence Closest Approach To Earth (2.735 AU)
Aug 12 - Perseids Meteor Shower Peak
Aug 12 - Asteroid 17681 Tweedledum Closest Approach To Earth (0.998 AU)
Aug 12 - Asteroid 69263 Big Ben Closest Approach To Earth (1.599 AU)
Aug 12 - 35th Anniversary (1978), ISEE-3 (ICE) Launch
Source: JPL Space Calendar Return to Contents
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Food for Thought
Ancient Astronomical Calendar Discovered in Scotland Predates Stonehenge
by 6,000 Years
A team from the University of Birmingham
recently announced an astronomical discovery in
Scotland marking the beginnings of recorded time.
Announced last month in the Journal of Internet
Archaeology, the Mesolithic monument consists of
a series of pits near Aberdeenshire, Scotland.
Estimated to date from 8,000 B.C., this 10,000 year
old structure would pre-date calendars discovered
in the Fertile Crescent region of the Middle East by
over 5,000 years.
But this is no ordinary wall calendar.
Originally unearthed by the National Trust for
Scotland in 2004, the site is designated as Warren
Field near the town of Crathes. It consists of 12 pits in an arc 54 metres long that seem to correspond with 12
lunar months, plus an added correction to bring the calendar back into sync with the solar year on the date of the
winter solstice.
―The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track
time across the years, to correct for seasonal drift of the lunar year‖ said team leader and professor of Landscape
Archaeology at the University of Birmingham Vince Gaffney.
We talked last week about the necessity of timekeeping as cultures moved from a hunter-gatherer to agrarian
lifestyle. Such abilities as marking the passage of the lunar cycles or the heliacal rising of the star Sirius gave
cultures the edge needed to dominate in their day.
For context, the pyramids on the plains of Giza date from around 2500 B.C., The Ice Man on display in Bolzano
Italy dates from 3,300 B.C., and the end of the last Ice Age was around 20,000 to 10,000 years ago, about the
time that the calendar was constructed.
―We have been taking photographs of the Scottish landscape for nearly 40 years, recording thousands of
archaeological sites that would never have been detected from the ground,‖ said manager of Aerial projects of
the Royal Commission of Aerial Survey Projects Dave Cowley. ―It‘s remarkable to think that our aerial survey
may have helped to find the place where time was invented.‖
The site at Warren Field was initially discovered during an aerial survey of the region.
The use of such a complex calendar by an ancient society also came as a revelation to researchers. Emeritus
Professor of Archaeoastronomy at the University of Leicester Clive Ruggles notes that the site ―represents a
combination of several different cycles which can be used to track time symbolically and practically.‖
The lunar synodic period, or the span of time that it takes for the Moon to return to the same phase (i.e., New-
to-New, Full-to-Full, etc) is approximately 29.5 days. Many cultures used a strictly lunar-based calendar
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composed of 12 synodic months. The Islamic calendar is an example of this sort of timekeeping still in use
today.
However, a 12 month lunar calendar also falls out of sync with our modern Gregorian calendar by 11 days (12
on leap years) per year.
The familiar Gregorian calendar is at the other extreme, a calendar that is strictly solar-based. The Gregorian
calendar was introduced in 1582 and is still in use today. This reconciled the 11 minute per year difference
between the Julian calendar and the mean solar year, which by the time of Pope Gregory‘s reform had already
caused the calendar to ―drift‖ by 10 days since the 1st Council of Nicaea 325 AD.
Surprisingly, the calendar discovered at Warren Field may be of a third and more complex variety, a luni-solar
calendar. This employs the use of intercalary periods, also known as embolismic months to bring the lunar and
solar calendar back into sync.
The modern Jewish calendar is an example of a luni-solar hybrid, which adds an extra month (known as the
2nd
Adar or Adar Sheni) every 2-3 years. This will next occur in March 2014.
The Greek astronomer Meton of Athens noted in 5th
century B.C. that 235 synodic periods very nearly add up to
19 years, to within a few hours. Today, this period bears his name, and is known as a metonic cycle. The
Babylonian astronomers were aware of this as well, and with the discovery at Warren Field, it seems that
ancient astronomers in Scotland may have been moving in this direction of advanced understanding as well.
It‘s interesting to note that the site at Warren Field also predates Stonehenge, the most famous ancient structure
in the United Kingdom by about 6,000 years. 10,000 years ago would have also seen the Earth‘s rotational north
celestial pole pointed near the +3.9th
magnitude star Rukbalgethi Shemali (Tau Herculis) in the modern day
constellation of Hercules. This is due to the 26,000 year wobble of our planet‘s axis known as the precession of
the equinoxes.
The Full Moon nearest the winter solstice also marks the ―Long Nights Moon,‖ when the Full Moon occupies a
space where the Sun resides during the summer months and rides high above the horizon for northern observers
all night. The ancients knew of the five degree tilt that our Moon has in relation to the ecliptic and how it can
ride exceptionally high in the sky every 18.6 years. We‘re currently headed towards a ‗shallow year‘ in 2015,
where the Moon rides low in relation to the ecliptic. From there, the Moon‘s path in the sky will get
progressively higher each year, peaking again in 2024.
Who built the Warren Field ruins along the scenic Dee Valley of Scotland? What other surprises are in store as
researchers excavate the site? One thing is for certain: the ancients were astute students of the sky. It‘s
fascinating to realize how much of our own history has yet to be told!
Source: Universe Today Return to Contents
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Space Image of the Week
(click image to view video on Vimeo)
The coolest video of an expanding supernova you'll see today
Image Credit & Copyright: Adam Block
When you look at the Crab Nebula, it's hard to fathom you're seeing exploded star remnants zipping outward
through space at 3 million miles per hour. After all, you could stare all night at the nebula—located some 6,500
light years from Earth—and fail to notice even a hint of motion.
However, if you wait, say, 13 years, you'll definitely detect some movement. That's exactly what professional
astrophotographer Adam Block did, using two images of the Crab Nebula taken more than a decade apart. He
created a video that fades back and forth between the two pictures, allowing you to see the nebula expand.
This animation shows the expansion of the Crab Nebula between the years of 1999 and 2012. 1999 picture was
taken by ESO using the VLT. The more recent picture was taken at the Mount Lemmon SkyCenter using the
0.8m Schulman Telescope. Visit Skycenter.arizona.edu
Source: The Planetary Society Return to Contents