Infrared image of the shockwave created by the massive giant star Zeta Ophiuchi in an interstellar dust cloud. Credit: NASA/JPL-Caltech; NASA and The Hubble Heritage Team (STScI/AURA); C. R. O'Dell, Vanderbilt University
An international research team led by the University of Vienna has made a major breakthrough. In a study recently published in Nature Astronomy, they describe how they conducted the first direct measurements of stellar wind in three Sun-like star systems. Using X-ray emission data obtained by the ESA’s X-ray Multi-Mirror-Newton (XMM-Newton) of these stars’ “astrospheres,” they measured the mass loss rate of these stars via stellar winds. The study of how stars and planets co-evolve could assist in the search for life while also helping astronomers predict the future evolution of our Solar System.
A future interstellar probe mission aims to travel beyond the heliosphere to the local interstellar medium to understand where our home came from and where it is going. Credit: John Hopkins Applied Physics Laboratory.
The edge of the Solar System is defined by the heliosphere and its heliopause. The heliopause marks the region where the interstellar medium stops the outgoing solar wind. But only two spacecraft, Voyager 1 and Voyager 2, have ever travelled to the heliopause. As a result, scientists are uncertain about the heliopause’s extent and its other properties.
Some scientists are keen to learn more about this region and are developing a mission concept to explore it.
Artist's depiction of a powerful gamma ray burst. Credit: NASA, ESA and M. Kornmesser
On October 9, 2022, a gamma-ray burst illuminated the solar system. Its light had traveled 2.4 billion years to reach us, having begun its journey when only bacteria and archaea existed on the Earth and oxygen was not yet plentiful in our air. Despite its long journey, the flash of light was tremendously bright.
When faced with a potentially mission-ending problem with NASA’s 15-year-old Interstellar Boundary Explorer (IBEX) spacecraft, engineers performed a time-honored procedure to fix it: they turned it off and then turned it back on again.
Success! IBEX is now fully operational again.
Actually, they told the spacecraft to turn itself off and IBEX – which unlike the famous HAL in “2001: A Space Odyssey,”– obeyed the command and then turned itself back on again.
An updated model suggests the shape of the Sun’s bubble of influence, the heliosphere (seen in yellow), may be a deflated croissant shape, rather than the long-tailed comet shape suggested by other research.
Credits: Opher, et al
At first glance, it looks like something from an alien autopsy. A strange organ cut from a xenomorph’s thorax, under the flickering lights of an operating room in a top secret government facility, with venous tendrils dangling down to the floor, dripping viscous slime. (X-Com anyone?)
A model of the heliosphere as imagined by new research. Yes, it looks like an ugly croissant. Image courtesy of Merav Opher, et. al
Every second of every day, our sun spits out a stream of tiny high-energy particles, known as the solar wind. This wind blows throughout the solar system, extending far beyond the orbits of the planets and out into interstellar space.
But the farther from the sun the wind gets, the more slowly it streams, changing from the raging torrent that the inner planets experience (strong enough to cause the aurora) into nothing more than an annoying drizzle. And far enough away – about twice the orbit of Neptune – it meets and mingles with all the random bits of energetic junk just floating around amongst the stars.
An artist concept depicting one of NASA's twin Voyager spacecraft, humanity's farthest and longest-lived spacecraft.
Voyager 2 just lost contact with Earth while Voyager 1 is still reporting back. Credit: NASA/JPL-Caltech
Only two of humanity’s spacecraft have left the Solar System: NASA’s Voyager 1 and Voyager 2. Voyager 1 left the heliosphere behind in 2012, while Voyager 2 did the same on Nov. 5th, 2018. Now Voyager 2 has been in interstellar space for one year, and five new papers are presenting the scientific results from that one year.
While it’s true that there’s no air to carry sound in space, starship explosions would be strangely silent and no one can hear you scream, this latest Science @ NASA video reminds us that “space can make music, if you know how to listen.”
And the “how” in this case is with the Plasma Wave Science Experiment aboard the Voyager 1 spacecraft, which is now playing the sounds of interstellar space — with a little help from University of Iowa physics professor and experiment principal investigator Don Gurnett. Watch the video above for a front-row seat (and read more about Voyager’s historic crossing of the heliosphere here.)
IBEX observations of spectral slope, where red and yellow indicate lower energy particles and green and blue higher energy ones. The central portion (circle) is looking down the heliotail and shows two lower energy “lobes” on the port and starboard sides and high energy regions at higher northern and southern latitudes.
Figure taken from McComas et al. , Astrophysical Journal, 2013.
Our Solar System is moving through interstellar space and scientists have long thought that the “bubble” around our Solar System – called the heliosphere – might have a tail, similar to how a comet has a tail or how other stars have astrospheres. But that has all been conjecture…. until now.
The IBEX spacecraft (Interstellar Boundary Explorer) has now seen the tail and has mapped out its structure. IBEX scientists were surprised to see the tail has twists and turns, with four separate “lobes,” making it appear somewhat like a four-leaf clover. This downwind region of the heliosphere is called the heliotail.
“Scientists have always presumed that the heliosphere had a tail,” said Eric Christian, IBEX mission scientist, speaking during a Google+ Hangout announcing the new findings. “But this is actually the first real data that we have to give us the shape of the tail.”
IBEX measures the neutral particles created by collisions at the solar system’s boundaries. This technique, called energetic neutral atom imaging, relies on the fact that the paths of neutral particles are not affected by the solar magnetic field. Instead, the particles travel in a straight line from collision to IBEX. Consequently, observing where the neutral particles came from describes what is going on in these distant regions.
“By collecting these energetic neutral atoms, IBEX provides maps of the original charged particles,” said David McComas, lead author on the team’s paper and principal investigator for IBEX at Southwest Research Institute. “The structures in the heliotail are invisible to our eyes, but we can use this trick to remotely image the outermost regions of our heliosphere.”
What they found was unexpected, McComas said.
“By very carefully assembling the statistical observations from the first three years of IBEX data we’ve been able to fill in what we couldn’t see before,” McComas said during the Hangout, “and what we found was that the heliotail was a much larger structure with a much more interesting configuration.
What they found was a tail that appears to have a combination of fast and slow moving particles. There are two lobes of slower particles on the sides, with faster particles above and below. The entire structure is twisted from the pushing and pulling of magnetic fields outside the solar system. McComas likened it to a how a beach ball might twist around if it was attached to a bungee cord.
The IBEX scientists speaking during the Hangout today said this new information will help us understand what the Voyager spacecraft may encounter as they reach the edge of our Solar System.
“IBEX and Voyager are incredibly complimentary missions,” said Christian. “I’ve often said that IBEX is like an MRI, where it can take an image to understand the big picture of what is going on, where the Voyagers are like biopsies, where we can see what is going on in the local area.”
This was the first time a NASA used a Google+ Hangout to broadcast a press briefing. You can watch the full Hangout below:
You can read David McComas’ blog post on the new findings here, and NASA’s press release here.
Fly along with NASA's Voyager spacecraft as the twin probes head towards interstellar space. In this artist's concept, a regularly updated gauge using data from the two spacecraft will indicate the levels of particles that originate from far outside our solar system and those that originate from inside our solar bubble. Those are two of the three signs scientists expect to see in interstellar space. The other sign is a change in the direction of the magnetic field. Image credit: NASA/JPL-Caltech
Far away, deep in the dark, near the edge of interstellar space, Voyager 1 and 2 are hurtling near the tenuous edge of the magnetic bubble surrounding the Sun known as the heliosphere and NASA wants you to ride along.
The Voyager website sports a new feature showing cosmic ray data. NASA’s Eyes on the Solar System, a popular Web-based interactive tool, contains a new Voyager module, that not only lets you ride along for the Voyagers’ journeys but also shows important scientific data flowing from the spacecraft.
[Warning:Play with this tool at your own risk. Interacting with this online feature can seriously impact your time; in an educational way, of course!]
As Voyager 1 explores the outer limits of the heliosphere, where the breath from our Sun is just a whisper, scientists are looking for three key signs that the spacecraft has left our solar system and entered interstellar space, or the space between stars. Voyager 1 began heading for the outer Solar System after zipping through the Saturn system in 1980.
The new module contains three gauges, updated every six hours from real data from Voyager 1 and 2, that indicate the level of fast-moving particles, slower-moving particles and the direction of the magnetic field. Fast-moving charged particles, mainly protons, come from distant stars and originate from outside the heliosphere. Slower-moving particles, also mainly protons, come from within the heliosphere. Scientists are looking for the levels of outside particles to jump dramatically while inside particles dip. If these levels hold steady, it means the Voyager spacecraft no longer feel the wind from our Sun and the gulf between stars awaits.
Over the past couple of years, data from Voyager 1, the most distant man-made object, show a steady increase of high-powered cosmic radiation indicating the edge is near, scientists say. Voyager 1 appears to have reached the last region before interstellar space. Scientists dubbed the region the “magnetic highway.” Particles from outside are streaming in while particles from inside are streaming out. Voyager 2’s instruments detect slight drops in inside particles but scientists don’t think the probe has entered the area yet.
Scientists also expect a change in the direction of the magnetic field. While particle data is updated every six hours, analyses of the magnetic field data usually takes a few months to prepare.
A snapshot riding along with Voyager 1’s looking back at the Sun and inner solar system. The positions of Voyager 2 and Pioneers 10 and 11 show within the viewport as well.
Although launched first, Voyager 2 lags behind its twin Voyager 1 by more than 20 times the distance between the Earth and the Sun. Voyager 2 blasted off August 20, 1977 aboard a Titan-Centaur rocket from Cape Canaveral, Florida. The nuclear-powered craft visited Jupiter and Saturn with an additional mission, called the Grand Tour, to study Uranus and Neptune. Voyager 1 launched two weeks later on September 5, 1977. With a faster flight path, Voyager 1 arrived at Jupiter four months before its sister craft. Voyager 1 went on to study Saturn before using the ringed planet’s gravity field to slingshot it up and out of the plane of the solar system toward the constellation Ophiuchus, the Serpent Bearer.
NASA’s Eyes on the Solar System allows viewers to hitch a ride with any of NASA’s spacecraft as they explore the solar system. Time can be slowed for a near approach of a moon or asteroid or sped up to coast between the planets. Watch close at just the right moment and you can witness one of the spacecrafts roll maneuvers. All spacecraft movements are based on actual spacecraft navigation data.
