Mystery Plumes: Did the Sun Bruise Mars?
Strange plumes have been spotted high in the Martian atmosphere that have, so far, defied explanation. Now scientists think space weather is to blame.
In recent years, the Red Planet has been doing something quite weird and scientist are stumped.
On a handful of occasions bizarre "plumes" have been observed protruding from Mars' upper atmosphere. A 2012 event was spotted by amateur astronomers and the phenomenon persisted for several days. Even the Hubble Space Telescope has been witness to a plume.
At first it was assumed some form of high-altitude cloud may be to blame, or maybe a storm kicked up dust into the upper atmosphere. But each hypothesis had its flaws and planetary scientists were left confused.
Now, European Space Agency scientists heading the Mars Express mission have studied this Martian oddity and found pretty strong evidence that the plumes aren't produced by the planet's weather; they're likely sparked by space weather.
Interactions between the sun and planetary environments are well known. As highly energized particles from the solar wind hit Earth's global magnetic field, for example, they can get trapped in the magnetosphere and funneled to high latitude regions. This influx of solar wind ions will collide with high-altitude atmospheric gases, causing them to glow, creating auroras. Where ever there's a magnetic field and an atmosphere, the sun can kick off a dazzling lightshow and we've seen auroras throughout the solar system, including Jupiter, Saturn and even Venus.
But solar interactions are not limited to auroras. When Earth is hit by coronal mass ejections - basically bubbles of magnetized plasma ejected from the sun's lower atmosphere - the entire planet's magnetic configuration can feel its effects, setting up powerful electrical currents through the atmosphere and energizing our ionosphere.
Mars, however, does not possess a global magnetic field to deflect the worst the sun can throw at it. When a CME hits Earth, the magnetosphere protects the atmosphere, but on Mars, lacking this magnetic shield, it suffers atmospheric erosion. Though it is thought Mars once had a thicker atmosphere, over billions of years, the constant flow of solar wind particles have stripped it away. Mars' atmosphere is, literally, leaking into space.
If space weather has such a powerful influence on Mars' atmospher loss, could it also be to blame for these odd plumes? Mars Express scientists have turned to their veteran Mars orbiter for answers.
The 2012 Mars plume made world headlines and Mars Express was there collecting data of the local space environment. Did a space weather event occur around the time the plume was observed?
"Our plasma observations tell us that there was a space weather event large enough to impact Mars and increase the escape of plasma from the planet's atmosphere," said David Andrews of the Swedish Institute of Space Physics in an ESA news release. "But we were not able to see any signatures in the ionosphere that we can categorically say were due to the presence of this plume."
There is circumstantial evidence that Mars' ionosphere - an upper layer of the atmosphere filled with charged particles, or ions - was in some way influenced by a space weather event, such as the impact of a CME. But because of the plume's location, it is a challenge acquire additional observations of the event, so just because there is some evidence a CME-triggered event is at play, it's circumstantial at best.
Now scientists are looking over archival data in the hope of finding occasions when a plume occurred during a CME hit. In 1997, for example, a Mars plume was spotted by Hubble and at around the same time, a fast CME was recorded as hitting Earth. Unfortunately there was no information from any Mars mission as to how that CME impacted the Red Planet's atmosphere, if it affected it at all.
"The jury is still out as to what physics is at play here, but given the altitude of the plume, we think that plasma interactions must be important," said Andrews. "One idea is that a fast-travelling CME causes a significant perturbation in the ionosphere resulting in dust and ice grains residing at high altitudes in the upper atmosphere being pushed around by the ionospheric plasma and magnetic fields, and then lofted to even higher altitudes by electrical charging."
This, argues Andrews, could produce an obvious plume in the upper atmosphere that can be seen from Earth. It's basically an atmospheric bruise cased by CME impact. But like all good mysteries, more data is needed, but it looks like we may finally be closing in on a possible explanation for these bizarre Martian plumes.
The realism of "The Martian" is getting the attention of NASA -- and not only because of what fictional NASA astronaut Mark Watney (Matt Damon) does on the surface. The agency has released several photographs showing real-life locations related to Watney's journey as he tries to get home to Earth. Also, the European Space Agency put out a map showing where Watney moved around on the surface (which we have put last in case you are worried about any spoilers.) Read on to see some of the places Watney had to think about when surviving on Mars.
Watney's journey begins in Acidalia Planitia, the landing site for his mission (Ares 3). Inside the crater you can see deposits that were blown there by the wind. Think about it -- as Watney and his crew moved around the crater, every place they went to, they were the first to put bootprints in that sand. The University of Arizona's HiRISE camera aboard the Mars Reconnaissance Orbiter helped gather data for this picture. "We can’t see the Ares 3 habitat because it arrives sometime in the future, so this is the 'before' image,"
earlier this year.
While we think of Mars as a place devoid of humans, we've sent several landing missions over the years. It turns out that Ares 3 is not so far away from the landing site of
and its rover, Sojourner -- the first rover to explore Mars in 1997. This image shows portions of the craft after it was deployed, such as the airbags and possibly parts of the heat shield. Since Pathfinder, NASA has sent three more rovers to the surface:
(2012). Opportunity and Curiosity are still working on the surface. The European Space Agency plans to send its first rover to Mars as part of the
As the name "Ares 3" implies, the Ares program is just one of a series of missions to Mars. Ares 4 is the next one, targeting a famous crater on the Martian surface: Schiaparelli Crater. Nearly 300 miles (500 kilometers) across, it's hard to get the entire thing into one high-resolution image, so this is just a portion of it taken with HiRISE. According to NASA, the agency has
like this for two reasons: the dust gets very warm during the day and cold at night (hard on equipment) and it's hard to know if there's anything interesting geologically in the bedrock underneath.
Here's a challenge about moving around on Mars: it's really hard to judge distance, because there are no familiar human markings to help us find our way around. Astronauts faced this challenge on the moon, and as Watney uses his rover on the surface, he has to be similarly careful not to go in the wrong direction or overstretch his rover's battery. Mawrth Crater is one of the landmarks Watney plots. "The crater rim is not very distinct, and from the Martian surface it would be quite difficult to tell that you are even on the rim of a crater,"
The Opportunity rover (which landed in 2004) is somewhat close to where Watney is moving around. It's possible that Watney draws inspiration from the plucky machine, which is still working well on Mars long past its original 90-Martian-day expiry date. Among Opportunity's major milestones: driving
finding extensive evidence of water around its landing site and beyond, and
While we initially could imagine craters as simple excavations of the surface, the Martian weather makes them far more complex than that. This is a
, somewhat near where Watney was moving on the surface. These thick deposits would be made either by water (in the ancient past, when Mars was wetter) or wind, based on what we know of similar processes on Earth. You don't see a lot of craters here because the deposits are so thin that the wind can easily erase any craters in the surface.
Here you can see Watney's journey across the surface of Mars, as mapped by the European Space Agency (and German Space Agency, DLR) based on imagery from the Mars Express spacecraft. The colors represent different heights of features on the Martian surface, with blue being lowest and red being highest. You can see how Watney had to carefully make his way between craters to reach his destination, the Ares 4 landing site.