Curiosity: planetary science and the latest Mars mission
Rebecca Ghent, Associate Professor in the Department of Earth Sciences, is a planetary scientist who works with NASA and researchers at various institutions to study geological processes on terrestrial planets.
As the latest Mars rover, Curiosity, hurtles towards the Red Planet and scientists around the world watch and wait, U of T News spoke with Ghent about why it's important to dig in the dust of planets and explore their rocky terrain.
You are a planetary scientist who focuses on terrestrial planets – can you explain what that means?
Planetary scientists concentrate on a range of physical processes taking place on the planets of our solar system (including Earth). The overarching goal of all planetary research is to understand the geological histories of the planets: what is occurring on these planets, from the surfaces to the deep interiors? How did they form, and how have they evolved? How are they similar to or different from one another, and what can the other planets tell us about Earth's history and eventual fate?
In order to answer these questions, we use a wide range of tools. My research has largely used imaging radar to explore the surfaces of Venus and the Moon, to investigate tectonic processes on Venus (e.g., mountain building) and impact cratering on the Moon, as well as the unprecedented volume of high-resolution datasets available for Mars, which I have used to investigate formation of the hundreds of thousands of small volcanic cones located in a large flat basin called Isidis Planitia.
Do you leave the gaseous planets to others because the earthy ones are more interesting?
Some members of our community focus on the "terrestrial" planets (Mercury, Venus, Earth, and Mars) and their satellites, and others focus on the gas giants or outer planets. There is also a lot of activity focused on asteroids and other small bodies. These sub-groups are not mutually exclusive, and there is much to be learned from communication with other workers with complementary experience and skills. The most interesting problems are best addressed using a combination of approaches.
Much of your research appears to focus on the moon – are you excited to see what the Curiosity finds on Mars?
Yes! The Curiosity rover and its payload instruments will deliver a wealth of new information about the rocks in Gale crater, which will help us understand the geological history of that region, and by extension, about Mars in general.
When the Curiosity enters the upper atmosphere of Mars, we’re told it will be travelling at a speed of more than 13,000 miles an hour – then it has seven minutes to execute a landing procedure which looks fairly complicated. Is there any concern that Curiosity’s two years on Mars could be over before they begin?
Landing on Mars is a tricky business, and success is never assured. This is why the community has taken to referring to the landing sequence as "Seven minutes of terror!". Though there is always concern during the entry, descent, and landing stages for any landed mission, the very best and most dedicated people have been working very hard for many years to achieve a safe landing for this rover. All of us will be anxiously waiting along with them to find out whether or not the landing has been successful.
The plan calls for Curiosity to gather rock samples from various layers of the Aeolis Mons – will these findings help your research?
One of the things I'm interested in is the physical characteristics of planetary regoliths - the surface layer of broken rock, dust, etc., that covers planetary surfaces. It's important to understand how this layer formed and has evolved, because it holds a record of the geological processes that have occurred on each planet. Mars has a very complex surface geological record involving the actions of wind, volcanism, impact cratering, and possibly, water; so this new information about the composition and physical characteristics of the rocks at the Curiosity landing site will provide valuable new insights into the roles of these various processes in forming Mars' surface rocks.
You’re part of a collaborative project with the Smithsonian Institution, NASA and Cornell University to image the nearside of the moon using radar. And you’re also part of something called the LRO Diviner thermal mapper science team, which has produced global temperature maps of the moon. Why is it important to map the moon in this way?
The histories of the Earth and the Moon are intimately related. In fact, the Moon and the Earth most likely came from the same parent body, very early in Solar System history. Yet fundamental questions about the Moon and its history remain to be answered.
We can address some of those fundamental questions by understanding the characteristics of the lunar regolith (surface layer of pulverized rock material, created by 4.6 billion years of impacts by objects ranging from microns to kilometers in size), the history of volcanism and impact cratering, and the chemical and physical makeup of lunar rocks. Those are the questions we aim to address using the Earth-based radar observations we collect using the Arecibo and Green Bank radio telescopes, and the thermal infrared observations collected by the Diviner instrument on the Lunar Reconnaissance Orbiter.
Your research also looks at asteroids – you’re part of the OSIRIS Rex mission science team which will be gathering samples from an asteroid in 2016. What do you hope to learn by studying this asteroid?
The asteroid 1999 RQ36, which is the object of study of the OSIRIS REx mission, is interesting for a number of reasons. First of all, it's in an Earth-crossing orbit, which means that it has the potential (though the probability is low) to collide with Earth. One of the OSIRIS REx objectives is to determine the orbit of this asteroid very precisely, and to determine how that orbit changes with time, so that we can better understand the risks posed by such near-Earth objects.
Second, RQ36 has a very primitive carbonaceous composition, and hasn't undergone much compositional change since its formation. This gives us the opportunity to study organic materials from the very early stages of Solar System formation, and to understand the role they might play in formation of the planets and other Solar System bodies as we know them.
Finally, the new information we'll gain from this mission will allow us to better understand remote observations (using radar and other telescopic methods) from other asteroids.