What should the towering peak inside Gale crater be called? Two names are being used — one is derived from longstanding classical mythology, while the other honors a beloved planetary geologist.
In a few weeks, after NASA's Curiosity rover — a.k.a. Mars Science Laboratory — has spent some time scratching and sniffing around its immediate environs, the rover will make tracks (so to speak) for its main objective: a towering peak that rises 3 miles (5 km) from the floor of Gale crater.
The huge massif was unknown to astronomers prior to spacecraft reconnaissance of Mars. In fact, early in the planning stages for Curiosity's journey, mission scientists referred to it simply as "The Mound." That seemed somewhat undignified for such an imposing and (for the rover) all-important feature, so they undertook an effort to name the mountain.
But the unintended result was two names: Aeolis Mons and Mount Sharp. Here's how this confusing outcome came about.
Back in 1973 the International Astronomical Union assigned the task of naming solar-system objects to a new committee, the Working Group for Planetary System Nomenclature (WGPSN). For nearly four decades WGSPN has seamlessly coordinated naming rights for dozens of solar-system bodies. Its members decided, for example, to name mountains on Mercury using the words for "hot" in various languages and craters on the moons of Uranus after characters in Shakespeare's plays.
In the case of Mars, large craters can be named after deceased scientists (along with writers and others) who have contributed to Martian knowledge and lore. But large mountains can not — and therein lies the crux of the issue regarding the object of Curiosity's forthcoming attention inside Gale crater.
You've probably heard "Mount Sharp" used a lot these past two weeks. It's the moniker favored by the mission scientists themselves. Many of them had close ties to Robert P. Sharp (1911–2004), a consummate field geologist and a key figure in formative years of planetary exploration. Sharp taught geology at Caltech from 1948 until well past retirement, influencing and guiding many current planetary scientists along the way.
"Bob Sharp was one of the best field geologists this country has ever had," says Michael Malin, who is one of Sharp's former students and now serves as principal investigator for two of the rover's 10 science instruments. Everyone on Curiosity's geologist-rich science team felt it would be entirely fitting to honor their later friend and mentor by naming The Mound after him. So in March they did just that.
"We received a request from the MSL team to name the mountain in Gale and a large crater adjacent to Gale," explains Brad Smith, who chairs the WGSPN's Mars Task Group. "They had suggested Sharp as a name for both." But mountain men were off limits according to IAU rules, and there's already a lunar crater named Sharp. "I suggested instead that the crater could be named Robert Sharp," Smith says, which was approved. About 95 miles (152 km), it lies just to Gale's west-northwest — Curiosity flew right over the crater as it dropped through the Martian sky last week.
The big mound does have a name that passes IAU muster: Aeolis Mons. Mons is Latin for mountain, and Aeolis is associated with a region of Mars identified by telescopic observers as far back as the 1870s. In Greek mythology, Aeolis was a floating island where winds were kept in a cave inside a mountain. The name has been formally associated with this region of Mars since 1958, when it was recognized as such by the International Astronomical Union.
According to the IAU's naming conventions, mountains of this large size must likewise carry mythological names. So in May, the Mars task group assigned it the name Aeolis Mons. It's part of a family of features in this region, such as Aeolis Planum (a plateau), Aeolis Dorsum (a ridge), and so forth. The flat expanse of crater floor that Curiosity landed on is named Aeolis Palus.
"I think it's an anachronistic system, and that the IAU should open up to special purposes," counters John Grotzinger, MSL's project scientist and a Caltech geologist who knew Sharp as well as anyone. "The people who spend so much time studying it should have a say in the matter." Grotzinger insists that he and his team will use Aeolis Mons once they publish the mission's results, but he sees no harm in using "Mount Sharp" when describing it informally to the news media and the public.
(Science writer Daniel Fischer has alerted me to at least one journal article, published last month, in which the MSL science team hasn't held to that pledge and chose to use "Mount Sharp" throughout.)
NASA's public-affairs folks initially made a modest attempt to note that "Mount Sharp" is an informal name, though Aeolis Mons appears nowhere in the 61-page guide to Curiosity's landing that they assembled for reporters. During the week of press briefings after the landing, I heard the project's key scientists use "Mount Sharp" dozens of times — which isn't surprising, since they're the ones who suggested it in the first place.
This isn't the first time that mission personnel have trumped tradition. In February 2004, just weeks after it thumped onto the floor of Gusev crater, the rover Spirit spied a clutch of distant mounds that NASA officials decided to name, individually and collectively, for the seven astronauts killed aboard the Space Shuttle Columbia one year earlier. Today, they're universally called the Columbia Hills, even in scientific literature, because, as Smith points out, "The IAU never received a request from the scientific community to provide a formal name for them."
I must admit that my allegiance is torn in the Gale case. Sky & Telescope has always made a point of adhering very closely to IAU conventions, and so have I. On the other hand, I took classes from Bob Sharp during my undergrad days at Caltech. If I hadn't, I probably wouldn't be typing these words now.
So we put the question to our e-newsletter subscribers. We set up a poll, asking readers to choose which name they liked best after reading the rationale for both names. The response, from more than 2,700 of you, gave tradition the edge: 57% voted for Aeolis Mons, compared to 43% for Mount Sharp. While our poll wasn't scientifically rigorous, it suggests there's ample room for both points of view. Some of the comments were fascinating; here's a sampling:
- Bill Wright: "What's the IAU's hangup with naming a Martian mountain after an ancient Greek myth? How Euro-centric can it get? Greek mythology is not Earth mythology."
- Jim Hamm: "I kind of like the Latin names, but rather than Aeolis Mons, how about calling it Curiositas Mons?"
- Guilio Pecora: "For any modern translator, Mons is the name of a nice, little Belgian city, whereas Mount Sharp is a name that can be understood fairly easily at any latitude on Earth."
- Anthony Barriero: "If you want to change the convention, join the International Astronomical Union and start a petition."
- Andrea Mazzoleni: "The use of the Latin doesn't disturb me. It is a 'dead' language neutral even to me in Italy."
I'm guessing that future articles about Curiosity's exploits — both here and in Sky & Telescope itself — will use wording to describe The Mound something like: "… Aeolis Mons, but known widely as Mount Sharp …" Maybe I should start compiling lots of generic synonyms so I don't have to use either one.
What's your take? Let me know your thoughts in the comments below.
By the way, Gale crater is named for Walter F. Gale (1865–1945), an Australian banker by day but a dedicated amateur astronomer by night who built his own telescopes and discovered a number of comets.