SciByte

more than 60,000 kilometers per hour

August 25, when solar particles disappeared for good

combined with a surge in higher-energy particles from other stars, suggested that Voyager had exited the heliosphere

Several well-publicized studies made that claim

colleagues resisted that conclusion

lacked evidence of what they thought would be the key signature of interstellar space: a shift in the direction of the magnetic field

Solar plasma produces a distinctive magnetic field because it all comes from the same source

scientists expected that the field would shift in interstellar space, where particles flit around in all directions

Not everyone agrees, including a few holdouts on the Voyager team

have written a paper demonstrating how plasma could become dense enough within the heliosphere to produce

measurement

many other astrophysicists say the evidence is overwhelming that Voyager 1 has crossed the heliopause, but they acknowledge that they have to determine why the magnetic field direction didn’t shift

NASA estimates that Voyager 1 has enough plutonium fuel to keep all its instruments powered for another seven years

August 25, 2012 — the same date, coincidentally, that the world lost its most famous human space explorer, Neil Armstrong

it is not farther out than the Oort Cloud

it will take 300 more years reach the Oort cloud and the spacecraft is closer to our Sun than any other star

the plasma environment Voyager 1 now travels through has definitely changed from what comes from our Sun to the plasma that is present in the space between stars.

debate

There’s also been a

between the latest various science papers and their authors

Scientists thought that when the spacecraft had crossed over into interstellar space, the magnetic field direction would change

that didn’t happen

scientists determined they needed to look at the properties of the plasma instead

The Sun’s heliosphere is filled with ionized plasma from the Sun

Outside that bubble, the plasma comes from the explosions of other stars millions of years ago

The main tell-tail difference is the interstellar plasma is denser.

the real instrument that was designed to make the measurements on the plasma quit working in the 1980’s

Instead they used the plasma wave instrument, located on the 10-meter long antennas on Voyager 1 and

from the Sun

a massive Coronal Mass Ejection

The antennas have radio receivers at the ends – “like the rabbit ears on old television sets

The CME erupted from the Sun in March 2012, and eventually arrived at Voyager 1′s location 13 months later, in April 2013

Because of the CME, the plasma around the spacecraft began to vibrate like a violin string

The pitch of the oscillations helped scientists determine the density of the plasma

the particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere

The plasma wave science team reviewed its data and found an earlier, fainter set of oscillations in October and November 2012 from other CMEs

extrapolation of measured plasma densities from both events, the team determined Voyager 1 first entered interstellar space in August 2012

certainly in a new region at the edge of the solar system where things are changing rapidly

not yet able to say that Voyager 1 has entered interstellar space

the data are changing in ways that the team didn’t expect

after further review, the Voyager team generally accepts the August 2012 date as the date of interstellar arrival

The charged particle and plasma changes were what would have been expected during a crossing of the heliopause

expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020

, it was first questioned in August of 2012, with more speculation in December 2012, then in March of 2013

Then about a month ago

Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft

emitted signals are currently very dim, at about 23 watts — the power of a refrigerator light bulb

Voyager mission controllers still talk to or receive data from Voyager 1 and Voyager 2 every day

planetary alignment that only happens every 176 years enabled the two spacecraft to join together to reach all the outer planets in a 12 year time period

By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt

Data from Voyager 1′s instruments are transmitted to Earth typically at 160 bits per second

signal from Voyager 1 takes about 17 hours to travel to Earth.

After the data are transmitted to JPL and processed by the science teams, Voyager data are made publicly available

Scientists do not know when Voyager 1 will reach the undisturbed part of interstellar space where there is no influence from our Sun

They also are not certain when Voyager 2 is expected to cross into interstellar space, but they believe it is not very far behind.

While Voyager 1 will keep going, we will not always be able to communicate with it, as we do now

In 2025 all instruments will be turned off, and the science team will be able to operate the spacecraft for about 10 years after that to just get engineering data

In the year 40,272 AD, Voyager 1 will come within 1.7 light years of an obscure star in the constellation Ursa Minor

For several months, the relative position of Voyager 1

remains some lingering evidence of the nearby heliosphere beyond the heliopause.

April

there are variations in some of Voyager's measurements that may be due to the nearby presence of the heliosphere

11.6 billion miles from the sun, or about 125 astronomical units.

it takes more than 17 hours for a radio signal to travel from the spacecraft

The signal strength is so incredibly weak that it takes both a 230-foot and a 110-foot-diameter antenna to receive our highest resolution data

moving outward from the sun at about 3.5 AU per year

Planetary Resources, Bellevue, Wash., began a Kickstarter crowdfunding campaign May 29 seeking to raise at least $1 million by June 30

14,919 space selfies, according data from Kickstarter

Kicktraq.com, shows that Planetary Resources raised an average of $45,614 a day, with the 17,614 donors contributing an average of $85 each

the first time a view of the two Martian satellites — called Phobos and Deimos — eclipsing each other has been captured from the vantage point of the planet's surface

researchers are studying the images to refine their knowledge of the orbits of Phobos and Deimos

ultimate goal is to improve orbit knowledge enough that we can improve the measurement of the tides Phobos raises on the Martian solid surface

Phobos' orbit is taking it closer to the surface of Mars very slowly

Deimos may gradually be getting farther and farther away from the planet

Phobos is just 14 miles (22 kilometers) wide on average, while Deimos is even smaller

But Curiosity was able to spot both of them because they orbit

3,700 miles (6,000 km) in Phobos' case and 12,470 miles (20,070 km) for Deimos

Earth's moon

a diameter of about 2,160 miles (3,475 km)

farther away — its average distance is 239,000 miles (384,600 km)

Phobos appears half as big in the sky to Curiosity as Earth's moon does to human skywatchers

Earth's moon