Friday, 04 April 2008
Cave Detection in the Thermal Infrared
NASA Spaceward Bound!
Image: Barrel cactus in the Mojave.
Our objectives of this mission to the Mojave was several fold: (1) collect thermal imagery over a 24 hour period to examine changes in detectability over a diurnal cycle; (2) iron out any problems with a new QWIP thermal imaging camera (developed by NASA-Goddard) before we hire an airplane to conduct overflights of caves in Hawaii; (3) obtain a better understanding regarding sensor placement in cave entrances and how this reflects actual cave entrance temperatures, and; (4) work with NASA Spaceward Bound! participants to show them how we are developing techniques to detect caves on Earth, the Moon and Mars.
Our team was comprised of Glen Cushing (the discoverer of cave-like features on Arsia Mons, Mars), Murzy Jhabvala (chief engineer, NASA-Goddard), and Matt Allner (University of North Dakota, space science graduate student). I have worked with all of these folks in various capacities over the past few years, and I am really looking forward to working with them again.
Image: Chuckwalla (Sauromalus obesus) on the lava flow. This lizard was about 1.5 feet long. This animal has a unique defensive mechanism. To avoid predation, it wedges itself within a crack or between two rocks and then inflats itself. Once the animal does this, it is virtually impossible to remove it. To demonstrate this, I touched the lizard once it was wedged in the rock. It makes a hissings sound as it inflates. Very cool, indeed!
Our plan was to collect imagery over a 24-hr period of a cave and non-cave feature. We want to know how these features behave thermally and try to gain insights into whether they behave in a similar manner. This is important of two reasons. Firstly, when applying thermal cave detection techniques to Mars and targeting caves that may be of interest from the perspective of their potential to harbor life, big caves are going to be of greater interest. Larger caves will be more protected and thus more likely to contain evidence of past or perhaps current life forms (provided, of course, life ever evolved on the Red Planet). This being the case, NASA will want to be able to differentiate between small caves and large caves – especially, if we plan to send rovers into these features one day. Secondly, non-cave features (alcoves, collapse pits, small tunnels, etc.) are going to be important targets for NASA for both the Moon and Mars. These features may be important for establishing temporary or perhaps permanent shelters for astronaut crews.
Image: Beavertail Cactus (Opuntia basilaris) in bloom.
We also wanted to test the new QWIP camera, which was recently made for Goddard to Murzy’s specifications. We are planning to overfly pit craters on Hawaii (which are strikingly similar to the features on Arsia Mons), and we wanted to make sure we had all the kinks ironed out, before we hired a plane and pilot. The last thing we want to do is deal with a myriad of technical issues, while we’re paying for flight time. Hopefully, by doing our homework in advance, we our Hawaiian overflight mission will be smoother.
Based on work we did in New Mexico and northern Arizona, results from our cave thermal behavior models suggested data from our temperature sensors placed in the cave entrance represent where the sensor was placed rather than the actual cave entrance temperature (we’re working on a paper, which we hope to have in review within the next few months). So, to test this hypothesis, we will place multiple sensors in the entrances of at least two caves. We will then take these data from the different sensors, subject them to a battery of statistical tests, and see if the temperature values are significantly different.
Finally, we are conducting these experiments in collaboration with NASA Spaceward Bound. The purpose of this project is to have scientists (who researching questions related to the development of techniques to the search for life on other objects within our solar system) train and work with science teachers. The hope is through this interaction, the teachers will generate teaching ideas to enhance their space science curriculum. This year, participants will either be pursuing a Bachelors or Masters degree in education with a science emphasis. So, my plan will be to demonstrate our thermal detection techniques, and show them how we are studying cave thermal behavior so that we may ultimately develop techniques for detecting caves on Earth, the Moon and Mars.
Glen and I left Flagstaff Friday afternoon. We met Matt in the Mojave National Preserve. We selected an excellent campsite in a thick yucca forest. It is mid-spring and the wild flowers were in bloom. The desert is a verdant green. It is a beautiful place to be, and even a better place to wake up in the morning.