NASA probes suggest magnetic bubbles reside at edge of solar system

Old and new views of the heliosheath. Red and blue spirals are the gracefully curving magnetic field lines of orthodox models. New data from Voyager add a magnetic froth (inset) to the mix.
Photo by NASA

By NASA Headquarters, Washington, D.C.
Published: June 9, 2011

While using a new computer model to analyze Voyager data, scientists found the Sun’s distant magnetic field is made up of bubbles approximately 100 million miles wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described in the June 9 edition of the Astrophysical Journal.

Like Earth, the Sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind or a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy.

The Voyager spacecraft, more than nine billion miles away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy.

“The Sun’s magnetic field extends all the way to the edge of the solar system,” said astronomer Merav Opher of Boston University. “Because the Sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina’s skirt. Far, far away from the Sun, where the Voyagers are, the folds of the skirt bunch up.”

Understanding the structure of the Sun’s magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how our star interacts with the rest of the galaxy.

So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data.

“We are still trying to wrap our minds around the implications of the findings,” said University of Maryland physicist Jim Drake, one of Opher’s colleagues.

First all-sky map of the edge of the solar system

This IBEX data image shows a dark sky map with the first orbit’s coincidence counts from hydrogen atoms at speeds from about 100,000 (161,000 km) to 36 million miles (58 million km) per hour. The IBEX team is collecting additional orbit data to expose adjacent swaths of the sky to reveal the edge of our solar system. SWRI, San Antonio, Texas

January 13, 2009
Provided by SWRI, San Antonio, Texas

Following two months of commissioning, during which the spacecraft and sensors were tuned for optimum mission performance, the Interstellar Boundary Explorer (IBEX) spacecraft began gathering data to build the first maps of the edge of the heliosphere, the region of space influenced by the Sun.

IBEX is using energetic neutral atom (ENA) imaging to create the first global maps of interactions between the million miles per hour (1,609,000 km/h) solar wind blown out in all directions by the Sun and the low-density material between the stars, known as the interstellar medium.

The maps are built by two ENA cameras, which collectively measure energetic neutral atoms coming in from the edge of the solar system with speeds from about 100,000 miles per hour (161,000 km/h) to some 36 million miles per hour (58 million km/h). Each sensor uses a charge-exchange process that converts incoming neutral atoms into charged ions so they can be analyzed and detected.

The sensors look out from opposite sides of the spacecraft in directions perpendicular to the Sun-pointed spin axis. As the spacecraft spins at four revolutions per minute, the measured ENAs fill in the pixels to build a circular swath that appears as a crescent on the map. As the spacecraft's spin axis tracks the Sun, the swaths move across the sky to complete the image.

"We are seeing fabulous initial results from IBEX, but, just as artisans use looms to build up colorful textiles by weaving one thread at a time, the IBEX sensors also need time - six months - to build up a complete map of the sky," said Dr. David McComas, IBEX principal investigator and senior executive director of the Space Science and Engineering Division at Southwest Research Institute in San Antonio, Texas. "So far, the intricate pattern of this fascinating interaction is only just beginning to disclose itself to us."

IBEX will enable researchers to examine the structures and dynamics of the outer heliosphere and to investigate the acceleration and propagation of charged particles in this complex and important region. IBEX also will address a serious challenge facing manned exploration by studying the region that shields Earth from the majority of galactic cosmic ray radiation.

"The space physics community is holding its collective breath waiting for these maps, which will provide a much deeper understanding of the Sun's interaction with the galaxy," said McComas. "We expect the first complete image, due this summer, to tell us a great deal about the heliosphere's fundamental nature."

See you again in 22000 years

photo: This image shows the orbit of the newly discovered solar system object SQ372 (blue), in comparison to the orbits of Neptune, Pluto, and Sedna (white, green, red). The location of the Sun is marked by the yellow dot at the center. The inset panel shows an expanded view, including the orbits of Uranus, Saturn, and Jupiter inside the orbit of Neptune. Even on this expanded scale, the size of Earth's orbit would be barely distinguishable from the central dot.

Astronomers find an unusual new denizen of the solar system

A "minor planet" with the prosaic name 2006 SQ372 is just over 2 billion miles from Earth, a bit closer than the planet Neptune. But this lump of ice and rock is beginning the return leg of a 22,500-year journey that will take it to a distance of 150 billion miles, nearly 1,600 times the distance from the Earth to the Sun, according to a team of researchers from the Sloan Digital Sky Survey (SDSS-II).

The discovery of this remarkable object was reported August 18 in Chicago, at an international symposium titled "The Sloan Digital Sky Survey: Asteroids to Cosmology." A paper describing the discovery technique and the properties of 2006 SQ372 is being prepared for submission to the Astrophysical Journal.

The orbital paths of the major planets are nearly circular, but the orbit of 2006 SQ372 is an ellipse that is 4 times longer than it is wide, says University of Washington astronomer Andrew Becker, who led the discovery team. The only known object with a comparable orbit is Sedna — a distant, Pluto-like dwarf planet discovered in 2003 — but 2006 SQ372's orbit takes it more than 1.5 times further from the Sun, and its orbital period is nearly twice as long.

The new object is much smaller than Sedna, Becker says, probably 30-60 miles across instead of nearly 1,000. "It's basically a comet, but it never gets close enough to the Sun to develop a long, bright tail of evaporated gas and dust."

Becker's team found 2006 SQ372 by applying a specialized computer searching algorithm to data taken for a completely different purpose: finding supernovae explosions billions of light-years away to measure the expansion of the universe. The SDSS-II supernovae survey scanned the same long stripe of sky, an area 1,000 times larger than the Full Moon, every clear night in the fall of 2005, 2006, and 2007.

"If you can find things that explode, you can also find things that move, but you need different tools to look for them," says team member Lynne Jones, also of the University of Washington. The only objects close enough to change position noticeably from one night to the next are in our own solar system, Jones explains.

SQ372 was first discovered in a series of images taken between September 27 and October 21, 2006. Team member Andrew Puckett, of the University of Alaska Anchorage, then searched the supernovae survey's fall 2005 observations to find earlier detections, thus securing the discovery. Subsequent SDSS detections of SQ372 have been found in data from the 2006 and 2007 observing seasons.

University of Washington graduate student Nathan Kaib, another member of the discovery team, has been running computer simulations to try to understand out how 2006 SQ372 might have acquired its unusual orbit. "It could have formed, like Pluto, in the belt of icy debris beyond Neptune, then been kicked to large distance by a gravitational encounter with Neptune or Uranus," says Kaib. "However, we think it is more probable that SQ372 comes from the inner edge of the Oort Cloud."

In 1950, Kaib explains, the Dutch astronomer Jan Oort hypothesized that most comets come from a distant reservoir of icy, asteroid-like bodies, which were ejected from the inner solar system by gravitational kicks from the giant planets as the planets themselves were forming 4.5 billion years ago. Most objects in the Oort Cloud orbit the Sun at distances of several trillion miles, but the gravity of passing stars can alter their orbits, flinging some into interstellar space and deflecting others to the inner solar system where they "light up" as comets.

Even at its most distant turning point, 2006 SQ372 will be 10 times closer to the Sun than the supposed main body of the Oort Cloud, says Kaib. "The existence of an 'inner' Oort Cloud has been theoretically predicted for many years, but SQ372 and perhaps Sedna are the first objects we have found that seem to originate there. It's exciting that we are beginning to verify these predictions."

Becker notes that 2006 SQ372 was bright enough to find with the SDSS only because it is near its closest approach to the Sun, and that the SDSS-II supernovae survey observed less than one percent of the sky. "There are bound to be many more objects like this waiting to be discovered by the next generation of surveys, which will search to fainter levels and cover more area," says Becker. "In a decade, we should know a lot more about this population than we do now."

"One of our goals," says Kaib, "is to understand the origin of comets, which are among the most spectacular celestial events. But the deeper goal is to look back into the early history of our solar system and piece together what was happening when the planets formed."

NASA Identifies Carbon-rich Molecules in Meteors as the 'Origin of Life'

Date:09.24.08
photo:These molecules, called quinones, are potentially significant for the “origin of life” or the habitability of planets.
Credit: NASA / Jenny Motar

Tons, perhaps tens of tons, of carbon molecules in dust particles and meteorites fall on Earth daily. Meteorites are especially valuable to astronomers because they provide relatively big chunks of carbon molecules that are easily analyzed in the laboratory. In the past few years, researchers have noticed that most meteorite carbon are molecules called polycyclic aromatic hydrocarbons (PAHs), which are very stable compounds and are survivors.

PAHs are the most common carbon-rich compound in the universe. They are found in everything from distant galaxies to charbroiled hamburgers and engine soot. When they are first formed, or found in space, their structures resemble pieces of chicken wire, fused six-sided rings. However, when found in meteorites, these aromatic rings are carrying extra hydrogen or oxygen.

Scientists at NASA Ames Research Center, Moffett Field, Calif. performed laboratory experiments that explain the process by which these meteoritic hydrocarbons attract the extra hydrogen and oxygen. They are very similar to the molecules identified as evidence of alien microbes in an earlier Science paper (McKay et al 1996).

“Our findings are important because it is the first time anybody explained these carbon-rich molecules found in meteorites. They are similar to the molecules that make-up living things,” said Max Bernstein, a space scientist at NASA Ames.

As it happened, their findings were judged significant enough to be award-winning. Published in Science (1999) by Bernstein and fellow NASA Ames scientists Scott Sanford and Louis Allamandola, their paper won the 2008 H. Julian Allen Award at NASA Ames Research Center.

It takes a long time for scientific papers to win awards.

“As scientists, we like to quantify things. Scientific papers are judged by the number of times they are cited in other scientific papers. Other scientists need to say that I couldn’t have written my paper without your paper. Often it takes a few years,” Bernstein explained.

These carbon-rich molecules are produced by carbon-rich, dying, giant red stars. When they are first formed, astronomers observe them as normal PAHs. However, when they are seen in meteorites billions of years later, they almost always have oxygen or heavy hydrogen attached to them. (Heavy hydrogen carries an extra neutron, and is called a deuterium isotope.) Something happened to change them, say scientists.

To study the process by which these carbon compounds change, the Ames Astrochemistry Laboratory studied PAHs in water ices that were exposed to ultraviolet radiation under space-like conditions. Scientists reproduced conditions including an incredibly high vacuum, extremely low temperatures (- 340 degrees Fahrenheit), and harsh radiation. When the extremely cold temperature was reached, these PAHs were exposed to ultraviolet radiation, and they changed. The experiment successfully reproduced the hydrocarbons found in meteorites. For the first time, scientists were able to show how hydrogen was exchanged for deuterium, or heavy hydrogen.

“It turns out, you only need water ice and radiation to change these molecules,” said Bernstein.

Using infrared spectroscopy, the Ames research team proved that the laboratory-produced hydrocarbons were the same hydrocarbons found in meteorites and observed through telescopes. Scientists observed the chemical reaction in a stainless steel chamber as it was happening. The laboratory sample reflected the same infrared colors as the hydrocarbons seen by astronomers using telescopes. Because the techniques used were the same, the results were directly comparable. “We were seeing the same molecules from telescopes as were reproduced in the laboratory,” said Sandford.

Once the molecular-size laboratory sample was retrieved, it was taken to Richard Zare’s laboratory at Stanford University, where researchers weighed the individual molecules. Findings showed that ices, modified by radiation, created new molecules.

These molecules, called quinones, received considerable attention by the astrobiology community because they are common to all life forms. They are potentially significant for the “origin of life” or the habitability of planets. How does a planet become habitable?

“Molecules from space helped to make the Earth the pleasant place that it is today,” said Allamandola, founder of the Ames Astrochemistry Laboratory.

“Our findings were new because we showed how these molecules formed. It was already known that these molecules were in meteorites and delivered to the planets,” said Bernstein.

“We now understand why these life-like carbon compounds are raining down on the Earth and other planets. Knowing this will help us search for life on other worlds by distinguishing these molecules from biomarkers,” said Bernstein.

An Astronomer Devoted to the Icy and Far Away

By CLAUDIA DREIFUS

Published: September 1, 2008

Heidi B. Hammel, 48, an M.I.T.-educated planetary astronomer, has two professional missions. The first is to learn everything possible about those icy planets, Neptune and Uranus. The second is to communicate knowledge about space to ordinary citizens. In 1994, when the Shoemaker-Levy 9 comet crashed into Jupiter, Dr. Hammel was the leader of the ground team that analyzed photos of the event from the Hubble Space Telescope. At the same time, she was the National Aeronautics and Space Administration’s public face, explaining the science to television audiences worldwide. We spoke at her home in Ridgefield, Conn., and later by telephone. An edited version of the conversations follows.

Q. NASA IS PREPARING A MISSION THAT WILL DO ONE LAST REPAIR OF THE HUBBLE SPACE TELESCOPE. AFTERWARD, IF HUBBLE MALFUNCTIONS, IT WILL BE ALLOWED TO DIE IN SPACE. DOES THAT TROUBLE YOU?

A. Listen, much as I love Hubble, it’s time to build new tools to see new things.

I’ve been working with a team planning the next great space observatory, the James Webb Space Telescope, scheduled for launch in 2013. Webb will be able to probe regions of the cosmos that are simply not visible to Hubble. It’s bigger and it will be tuned to wavelengths that Hubble can’t really see. With Webb, we have the potential to answer questions about the origins of just about everything in the universe.

Q. WHY DOES IT HAVE TO BE HUBBLE OR WEBB? WOULDN’T ASTRONOMERS LIKE TO HAVE BOTH?

A. There isn’t enough money to do everything. Hubble’s already lasted much longer than people expected. It wasn’t meant to last forever.

Q. LET’S TALK ABOUT YOUR SCIENCE. DO YOU THINK ASTRONOMERS ARE SOMETHING LIKE DETECTIVES — OR INVESTIGATIVE REPORTERS?

A. I think all scientists are like detectives. We are most happy when we find something that doesn’t fit our expectations. My work often involves analyzing images of the planets taken by Hubble or made at Earth-based telescopes like the Keck in Hawaii. If I see something that seems out of sync with what’s already known, the first thing I do is try to find out what’s wrong with the data. Once you’ve done that, and it still seems wrong, that’s when things get interesting. It means you’ve found something new to understand. So you think about it and go for more data and come up with different models. All real science is like that.

Q. CAN YOU GIVE ME AN EXAMPLE OF THIS FROM YOUR RESEARCH?

A. In 1989, when Voyager 2 flew by Neptune, we saw, for the first time, a great dark spot in that planet’s southern hemisphere. I went to an Earth-based telescope to look at it in real time. Well, lo and behold, the dark spot wasn’t visible. All I could see were these bright clouds alongside where the dark spot was supposed to be.

Then in 1993, I looked at Neptune again and all the bright stuff was now in the northern hemisphere. A year later Hubble sent back Neptune images, and on those pictures the southern dark spot was definitely gone. So far, it hasn’t come back. We don’t know why.

But we did learn something new: that Neptune could change dramatically in just five years. Till then, it was thought that Neptune was more static.

Q. YOUR EXPERTISE IS NEPTUNE AND URANUS, GENERALLY THOUGHT TO BE THE DULLEST PLANETS IN THE SOLAR SYSTEM. WHY DID YOU PICK SUCH UNCHARISMATIC BODIES TO STUDY?

A. They are not dull. They change a lot. But yes, they are the Rodney Dangerfield of the solar system — they don’t get respect. What are they called? “The Icy Giants.” Actually, they are great for a researcher. Because they are located at the outer reaches of the solar system, they’ve been less studied than nearer planets. So whenever I make an observation, anything I find is brand new.

With Uranus, now we’re rewriting the textbooks on it. Our recent observations are so counter to what we thought. We are going through a different season right now on Uranus, and the whole planet’s atmosphere is turning on, bright clouds, great dark spots, all sorts of convective activity, which 20 years ago we didn’t see. We thought of Uranus’s atmosphere as pretty much dead. And it’s not.

Q. THOUGH IT’S NOT YOUR PLANET, HAVE YOU BEEN FOLLOWING THE RECENT NEWS FROM MARS?

A. Yes. And it’s very exciting. The soil is good. There’s ice. There may be places where the ice is more accessible. It means that there aren’t physical reasons to stop us from colonizing that place, if that’s what the fate of humanity is going to be. We are finally being able to determine what Mars is made of.

I try to stay on top of the Mars findings because at some level the solar system is unified. Things that happen in one part are relevant to other parts. The chemistry on the Mars surface informs our understanding of the chemistry elsewhere in solar system.

Q. ARE WE GETTING ANY CLOSER TO DISCOVERING POSSIBLE LIFE OUTSIDE THE SOLAR SYSTEM?

A. That’s become a fun question now that we’re discovering planets around other stars. I have this widget on my computer that gives me a running total of how many new extra-solar planets have been found. It’s over 300. Most of them were located in the past few years, and the pace of discovery is accelerating.

We have to take it one step at a time. The first step is to locate an Earth-size planet the right distance from its own star for water to have been in liquid form long enough to allow life, as we know it, to develop. The next question will be: How can we tell if life is present, because this body will be too far away to take pictures of it? We will have to look at the chemistry of its atmosphere and look for signs that it has been modified by the presence of life. That will be the clue.

Q. HOW DID YOU DEVELOP YOUR TALENT FOR EXPLAINING SCIENCE IN POPULAR TERMS?

A. My Uncle Larry was my template. When I was a student, I’d come home on Thanksgiving weekends, and during breaks in his football game he’d go, “O.K., Heidi, whatcha workin’ on?” I knew I had 30 seconds to tell this guy who worked in a Mack truck factory what I did. He just wanted the big picture. I’d quickly say, “I’m using big telescopes to try to find planets and figure out what they’re made of.” Every scientist should be able to do that.

Q. YOU DO YOUR ASTRONOMY FROM A HOME OFFICE. HOW DO YOU MANAGE THAT?

A. All you need is computers and high-speed network contact. I’ve got one computer that’s connected to the Internet and another one that’s walled off from it. One is for data analysis and the other is for e-mails.

Q. HOW DO YOU KEEP YOUR THREE YOUNG CHILDREN “WALLED OFF” FROM YOUR WORK?

A. They and my husband have had to learn that when my office door is closed, it’s closed. I’ve had to learn how to prioritize. You have to budget time for the inevitable problems that come up with children. You have to always be ahead of the game. If your proposal is due at NASA on Friday, it has to be finished on Wednesday because, on Thursday, it could be fevers and head lice.