Space

June 28, 2013

NASA’s Voyager 1 explores final frontier of our ‘solar bubble’

Data from Voyager 1, now more than 11 billion miles from the sun, suggest the spacecraft is closer to becoming the first human-made object to reach interstellar space.

Research using Voyager 1 data and published in the journal Science June 27 provides new detail on the last region the spacecraft will cross before it leaves the heliosphere, or the bubble around our sun, and enters interstellar space. Three papers describe how Voyager 1′s entry into a region called the magnetic highway resulted in simultaneous observations of the highest rate so far of charged particles from outside heliosphere and the disappearance of charged particles from inside the heliosphere.

Scientists have seen two of the three signs of interstellar arrival they expected to see: charged particles disappearing as they zoom out along the solar magnetic field and cosmic rays from far outside zooming in. Scientists have not yet seen the third sign, an abrupt change in the direction of the magnetic field, which would indicate the presence of the interstellar magnetic field.

“This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind’s most distant scout,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun’s magnetic field.”

Scientists do not know exactly how far Voyager 1 has to go to reach interstellar space. They estimate it could take several more months, or even years, to get there. The heliosphere extends at least 8 billion miles beyond all the planets in our solar system. It is dominated by the sun’s magnetic field and an ionized wind expanding outward from the sun. Outside the heliosphere, interstellar space is filled with matter from other stars and the magnetic field present in the nearby region of the Milky Way.

Voyager 1 and its twin spacecraft, Voyager 2, were launched in 1977. They toured Jupiter, Saturn, Uranus and Neptune before embarking on their interstellar mission in 1990. They now aim to leave the heliosphere. Measuring the size of the heliosphere is part of the Voyagers’ mission.

The Science papers focus on observations made from May to September 2012 by Voyager 1′s cosmic ray, low-energy charged particle and magnetometer instruments, with some additional charged particle data obtained through April of this year.

Voyager 2 is about 9 billion miles from the sun and still inside the heliosphere. Voyager 1 was about 11 billion miles from the sun Aug. 25 when it reached the magnetic highway, also known as the depletion region, and a connection to interstellar space. This region allows charged particles to travel into and out of the heliosphere along a smooth magnetic field line, instead of bouncing round in all directions as if trapped on local roads. For the first time in this region, scientists could detect low-energy cosmic rays that originate from dying stars.

“We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway,” said Stamatios Krimigis, the low-energy charged particle instrument’s principal investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago.”

Other charged particle behavior observed by Voyager 1 also indicates the spacecraft still is in a region of transition to the interstellar medium. While crossing into the new region, the charged particles originating from the heliosphere that decreased most quickly were those shooting straightest along solar magnetic field lines. Particles moving perpendicular to the magnetic field did not decrease as quickly. However, cosmic rays moving along the field lines in the magnetic highway region were somewhat more populous than those moving perpendicular to the field. In interstellar space, the direction of the moving charged particles is not expected to matter.

In the span of about 24 hours, the magnetic field originating from the sun also began piling up, like cars backed up on a freeway exit ramp. But scientists were able to quantify the magnetic field barely changed direction – by no more than 2 degrees.

“A day made such a difference in this region with the magnetic field suddenly doubling and becoming extraordinarily smooth,” said Leonard Burlaga, the lead author of one of the papers, and based at NASA’s Goddard Space Flight Center in Greenbelt, Md. “But since there was no significant change in the magnetic field direction, we’re still observing the field lines originating at the sun.”

NASA’s Jet Propulsion Laboratory, in Pasadena, Calif., built and operates the Voyager spacecraft. California Institute of Technology in Pasadena manages JPL for NASA. The Voyager missions are a part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.

 




All of this week's top headlines to your email every Friday.


 
 

 

NASA awards research facilities, engineering support services contract

NASA has awarded a contract for research facilities and engineering support services to InuTeq, LLC of Greenbelt, Maryland, in support of the Mission Information and Test Systems Directorate at NASA’s Armstrong Flight Research Center, Edwards, Calif. This cost-plus-award-fee contract covers a one-year base period beginning Nov. 1, 2014 and four one-year options, and is valued...
 
 

NASA awards contract option on test, operations support contract

NASA has exercised the first option to extend the period of performance of its Test and Operations Support Contract with Jacobs Technology Inc. of Tullahoma, Tenn., to Sept. 30, 2016. Jacobs Technology Inc. will provide continued overall management and implementation of ground systems capabilities, flight hardware processing and launch operations in support of the International...
 
 

NASA’s New Horizons spacecraft crosses Neptune orbit

NASA’s Pluto-bound New Horizons spacecraft has traversed the orbit of Neptune. This is its last major crossing en route to becoming the first probe to make a close encounter with distant Pluto on July 14, 2015. The sophisticated piano-sized spacecraft, which launched in January 2006, reached Neptune’s orbit – nearly 2.75 billion miles from Earth...
 

 

NASA awards program analysis, Control Bridge III Contract

NASA has awarded the Program Analysis and Control III Bridge contract for support services to ASRC Research & Technology Solutions of Beltsville, Md. The cost-plus-fixed-fee, indefinite delivery/indefinite quantity basic contract has a minimum ordering value of $1 million and a maximum ordering value of $37 million, with a performance period beginning Aug. 30 through Feb....
 
 

NASA selects 26 space biology research proposals

NASA’s Space Biology Program will fund 26 proposals to investigate how microbes, cells, plants and animals respond to changes in gravity. The research will be conducted aboard the International Space Station. The research will help uncover new basic knowledge that other NASA researchers and engineers can use to solve problems confronting human exploration of space...
 
 
NASA image

Ozone-depleting compound persists, NASA research shows

NASA image Satellites observed the largest ozone hole over Antarctica in 2006. Purple and blue represent areas of low ozone concentrations in the atmosphere; yellow and red are areas of higher concentrations. NASA research show...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>