Space

Mission engineers at NASA have turned off the plasma science instrument aboard the Voyager 2 spacecraft due to the probe’s gradually shrinking electrical power supply.

Traveling more than 12.8 billion miles (20.5 billion kilometers) from Earth, the spacecraft continues to use four science instruments to study the region outside our heliosphere, the protective bubble of particles and magnetic fields created by the Sun. The probe has enough power to continue exploring this region with at least one operational science instrument into the 2030s.

Mission engineers have taken steps to avoid turning off a science instrument for as long as possible because the science data collected by the twin Voyager probes is unique. No other human-made spacecraft has operated in interstellar space, the region outside the heliosphere.

The plasma science instrument measures the amount of plasma (electrically charged atoms) and the direction it is flowing. It has collected limited data in recent years due to its orientation relative to the direction that plasma is flowing in interstellar space.

Both spacecraft are powered by decaying plutonium and lose about 4 watts of power each year. After the twin Voyagers completed their exploration of the giant planets in the 1980s, the mission team turned off several science instruments that would not be used in the study of interstellar space. That gave the spacecraft plenty of extra power until a few years ago. Since then, the team has turned off all onboard systems not essential for keeping the probes working, including some heaters. In order to postpone having to shut off another science instrument, they also adjusted how Voyager 2’ voltage is monitored.

Monitoring Results

On Sept. 26, engineers issued the command to turn off the plasma science instrument. Sent by NASA’s Deep Space Network, it took 19 hours to reach Voyager 2, and the return signal took another 19 hours to reach Earth.

Mission engineers always carefully monitor changes being made to the 47-year-old spacecraft’s operations to ensure they don’t generate any unwanted secondary effects. The team has confirmed that the switch-off command was executed without incident and the probe is operating normally.

In 2018, the plasma science instrument proved critical in determining that Voyager 2 left the heliosphere. The boundary between the heliosphere and interstellar space is demarcated by changes in the atoms, particles, and magnetic fields that instruments on the Voyagers can detect. Inside the heliosphere, particles from the Sun flow outward, away from our nearest star. The heliosphere is moving through interstellar space, so at Voyager 2’s position near the front of the solar bubble, the plasma flows in almost the opposite direction of the solar particles.

The plasma science instrument consists of four “cups.” Three cups point in the direction of the Sun and observed the solar wind while inside the heliosphere. A fourth points at a right angle to the direction of the other three and has observed the plasma in planetary magnetospheres, the heliosphere, and now, interstellar space.

When Voyager 2 exited the heliosphere, the flow of plasma into the three cups facing the Sun dropped off dramatically. The most useful data from the fourth cup comes only once every three months, when the spacecraft does a 360-degree turn on the axis pointed toward the Sun. This factored into the mission’s decision to turn this instrument off before others.

The plasma science instrument on Voyager 1 stopped working in 1980 and was turned off in 2007 to save power. Another instrument aboard Voyager 2, called the plasma wave subsystem, can estimate the plasma density when eruptions from the Sun drive shocks through the interstellar medium, producing plasma waves.

The Voyager team continues to monitor the health of the spacecraft and its available resources to make engineering decisions that maximize the mission’s science output.

For more information about NASA’s Voyager missions, visit:

https://science.nasa.gov/mission/voyager

Note: Whole article available in post as it from a US government agency and is not bound by copyright.

Mars' missing atmosphere may be locked up in the planet's clay-rich surface, a new study by MIT geologists has suggested.

According to the researchers, ancient water trickling through Mars' rocks could have triggered a series of chemical reactions, converting CO2 into methane and trapping the carbon in clay minerals for billions of years.

Billions of years ago, Mars was a very different place—likely wet, with rivers flowing across its surface and a thick atmosphere of carbon dioxide (CO2) insulating the planet. However, around 3.5 billion years ago, the red planet's atmosphere thinned and its water dried up, leaving behind the cold desert we see today.

A central mystery in planetary science has been: where did all that carbon dioxide go?

The universe’s hidden mass may be made of black holes, which could wobble the planets of the solar system when they pass by

Black holes the size of an atom that contain the mass of an asteroid may fly through the inner solar system about once a decade, scientists say. Theoretically created just after the big bang, these examples of so-called primordial black holes could explain the missing dark matter thought to dominate our universe. And if they sneak by the moon or Mars, scientists should be able to detect them, a new study shows.

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If primordial black holes are responsible for dark matter, they probably zip through the solar system about every 10 years, a new study found. If one of these black holes comes near a planet or large moon, it should push the body off course enough to be measurable by current instruments. “As it passes by, the planet starts to wobble,” says Sarah R. Geller, a theoretical physicist now at the University of California, Santa Cruz, and co-author of the study, which was published on September 17 in Physical Review D.* “The wobble will grow over a few years but eventually it will damp out and go back to zero.”

Black hole jets, which spew near-light-speed particle beams, can trigger nearby white dwarf stars to explode by igniting hydrogen layers on their surfaces. "We don't know what's going on, but it's just a very exciting finding," said Alec Lessing, an astrophysicist at Stanford University and lead author of a new study describing the phenomenon, in an ESA release. Gizmodo reports:

In the recent work -- set to publish in The Astrophysical Journal and is currently hosted on the preprint server arXiv -- the team studied 135 novae in the galaxy M87, which hosts a supermassive black hole of the same name at its core. M87 is 6.5 billion times the mass of the Sun and was the first black hole to be directly imaged, in work done in 2019 by the Event Horizon Telescope Collaboration. The team found twice as many novae erupting near M87's 3,000 light-year-long plasma jet than elsewhere in the galaxy. The Hubble Space Telescope also directly imaged M87's jet, which you can see below in luminous blue detail. Though it looks fairly calm in the image, the distance deceives you: this is a long tendril of superheated, near-light speed particles, somehow triggering stars to erupt.

Though previous researchers had suggested there was more activity in the jet's vicinity, new observations with Hubble's wider-view cameras revealed more of the novae brightening -- indicating they were blowing hydrogen up off their surface layers. "There's something that the jet is doing to the star systems that wander into the surrounding neighborhood. Maybe the jet somehow snowplows hydrogen fuel onto the white dwarfs, causing them to erupt more frequently," Lessing said in the release. "But it's not clear that it's a physical pushing. It could be the effect of the pressure of the light emanating from the jet. When you deliver hydrogen faster, you get eruptions faster." The new Hubble images of M87 are also the deepest yet taken, thanks to the newer cameras on Hubble. Though the team wrote in the paper that there's between a 0.1% to 1% chance that their observations can be chalked up to randomness, most signs point to the jet somehow catalyzing the stellar eruptions.

So many interesting things come out of NIAC funding

https://images.nasa.gov/details/PIA26362

I just saw Saturn as a super bright dot next to the moon. Apparently it'll be visible for a stretch throughout September, with Neptune also coming into view later this month.

Make sure to take a look at the night sky sometime this month if you want to see some planets!