SKY REPORTER: Mars Fever!

I recently read: “NASA to Announce Mars Mystery Solved” and it made my heart beat faster. Had proof of Martian life been found? If not living, breathing, and pumping out methane, at least some solid evidentiary trace from eons ago—that could be the greatest scientific discovery ever. However, the heralded news conference September 28, led by James L. Green, director of NASA’s planetary science division, revealed no such evidence. Nevertheless, details were revealed about a place on the red planet where water recently flowed—not the ultimate revelation but perhaps a step in that direction.

Warm season flows on the slopes of Horowitz Crater on Mars.
Credit: JPL/NASA

For years it’s been known Mars's atmosphere contains traces of water vapor, and during a five month period in 2008 water ice was found by the Phoenix Laboratory after gently setting down at northern Martian latitude 68.22°. It’s an icy place, whimsically dubbed Green Valley indicating a relatively safe landing site as opposed to a rock strewn, dangerous area for a spacecraft.

Phoenix discovered a frozen water layer five to eighteen centimeters beneath the surface after digging with the laboratory’s robotic arm. Minerals and salts amounting to several percent of the soil’s weight that only could have been formed in water were also identified. At the end of that Martian summer, snow and ice began covering the site and subsequently destroyed the lander’s ability to communicate with Earth.

Despite previous knowledge about water on Mars, recognition of recently flowing water was a big step in our quest for evidence of possible extraterrestrial life. Streaks about 100 yards long, described as "recurring slope lineae, or RSL" are visible on images of Horowitz Crater at 32.04° S 219.36° W. The crater was named after Norman Horowitz, a geneticist at the California Institute of Technology, who designed Pyrolytic Release experiments aboard Viking lander craft that reached Mars in 1976. That mission initiated the first direct analysis of Martian surface properties and specifically looked for biosignatures of microbial life. Initial reports of positive results spurred enduring debate, general denial, and motivation for more direct experimentation.

Images of streaks on Horowitz Crater were obtained via the High Resolution Imaging Science Experiment (HiRISE) camera carried on NASA's Mars Reconnaissance Orbiter, which has been extensively surveying the red planet since 2006. The recent announcement was in keeping with the refrain, “follow the water,” as we continue searching for proof we’re not alone in the universe. 

Since the start of this century, thousands of gullies have been identified on Mars, with some exhibiting dendritic patterns and terminating in deltas evoking images of earthly rivulets and rivers. Obvious association of these Martian structures with running water on Earth was countered by some researchers who believe the features on Mars could instead have been formed by blowing sand or possibly by effects related to freezing and sublimating of carbon dioxide, thereby lubricating surface particles that might flow and carve the gullies. Dry ice (frozen carbon dioxide) is a permanent feature of Martian polar caps easily visible from Earth with even small telescopes when the Mars is nearest Earth. At middle Martian latitudes, night temperatures in winter may plummet sufficiently to allow for some dry ice to form. Another minority concept suggests winter buildups of large dry ice chunks could break loose causing gully forming avalanches.

NASA’s announcement of periodically running water at Horowitz Crater came from research using the Compact Reconnaissance Imaging Spectrometer aboard the Mars Reconnaissance Orbiter to analyze reflected sunlight from the streaks, thereby detecting spectral signatures of hydrated salts consistent with deposition by flows of salty water that evidently formed the dramatic slope lineae.

By coincidence (maybe), Ridley Scott’s new movie “The Martian” was released five days after NASA’s Horowitz Crater news conference.

If you want to directly see Mars for yourself this month, good opportunities are described below when the red planet will appear in our predawn sky near the crescent Moon and bright Jupiter.

The Moon

The Planets

Of the planets visible with unaided eyes, only Saturn remains above the horizon during early evenings. For several hours before sunrise this month Venus and Jupiter shine as prominent features.

During early October, several notably bright objects are concentrated within the borders of the constellation Leo, visible above the eastern horizon before start of morning twilight. Thursday the eighth, a waning crescent Moon, four days before New, forms a celestial triad with brilliant Venus and first magnitude star Regulus at the front of Leo’s figure. By 5 a.m. that morning, Jupiter and Mars are also above the eastern horizon near the zodiacal Lion’s hind feet.

On the morning of October 9, look above the eastern horizon between 5 a.m. and the advent of twilight. The Moon will then be four degrees right of Mars and six degrees to the upper right of bright Jupiter. Mars is currently a subject of much media buzz, and it currently has a visual magnitude of +1.8 while that of Jupiter coincidently is –1.8. By virtue of its much larger size and greater surface reflectivity, despite being considerably further from us than the red planet; Jupiter currently appears 27 times brighter than Mars. At mid month, with a distance of 577 million miles, Jupiter is about two and a half times more distant from us than Mars.

The evening of Friday the 16th, a waxing crescent Moon is situated low in the southwestern sky about five degrees to the upper left of Saturn, which is ten degrees above the horizon at 7 p.m. That great ringed planet currently shines at magnitude +0.6. First magnitude Antares, brightest star in Scorpius, is then nine degrees to the left of Saturn.

During the week of October 15, Mars approaches Jupiter’s direction in the predawn sky. On the mornings of Saturday October 17 and Sunday the 18th, the two planets are separated by just a half degree of arc. Jupiter is easy to spot, as it’s second only to Venus as a bright feature of the early morning sky that week. Once you identify Jupiter, Mars may be seen to the upper left of the brighter planet on the 17th and to Jupiter’s lower left on Sunday morning, the 18th.

Further aspects of this month’s early morning planet show continue to evolve as Venus moves to a nearly straight equally spaced line above Jupiter and Mars during early morning of Friday October 23. Apparent separations between each planet are then about 2.3 angular degrees, equivalent to just a finger’s width seen at arm’s length.

On Halloween night, the 74%-illuminated, waning gibbous Moon rises at 9:51 p.m.