A group of Hopkins scientists has recently been awarded a $750,000 grant to build a mass spectrometer to be put on an upcoming Mars rover. This new device will be used to search for life on Mars.
As the Mars rover combs over the planet, the mass spectrometer will search for organic chemicals -- the chemicals of life. The mission, expected to launch in 2013, will search core samples of rock for nucleic acids or proteins.
NASA awarded the grant to scientists at the Hopkins School of Medicine, in collaboration with scientists from the University of California-Santa Barbara and the JHU Applied Physics Laboratory (APL). Robert Cotter, a molecular scientist and pharmacologist at the medical school, is one of the lead scientists on the project.
Cotter explains: "What is special is that this will be the first mass spectrometer designed for space to look at larger molecules. This is consistent with NASA's emphasis on looking for `signs of life.' This in turn refers not necessarily to whether there is life on Mars but whether there are signs that life may have existed or may have attempted to start. The idea is that smaller molecules would then have long since evaporated, so ... this instrument will be looking for larger, more complex organic molecules."
Cotter earned his Ph.D. from the Homewood campus in the Chemistry Department, where his thesis work concentrated on building mass spectrometers.
The mass spectrometer being built acts as an "ion trap," as Cotter calls it. A laser is directed at a core sample beneath Mars' surface, and the spectrometer captures ions formed by the laser pulse. The ions are then fed into a detector that processes them in order of mass. A mass spectrum is then determined.
Cotter says of this model, compared to previous ones, "The uniqueness of this design is that it will provide a reasonably high mass range (2,000 Daltons) at a relatively low voltage (300 V) compared with existing commercial traps that work at several kilovolts. This reduces the chance of `arcing' in the low-pressure atmosphere of Mars, while also reducing the power consumption."
The mass spectrometer is actually a miniaturized version of a standard spectrometer. "While getting better, the tool has gotten smaller as well. Original versions were just so big and took up so much space that it was impossible to do much else in the lab," Cotter said in a recent press release.
Currently, the mass spectrometer is able to fit into a machine around the size of a mini-fridge. But for the Mars rover, Cotter and his team are charged with getting one to fit into a machine the size of a shoebox. "It's going to be tough, not only to miniaturize all the intricate functions but to build the instrument to survive the harsh travel conditions en route and the environmental conditions once it lands," Cotter said.
Mass spectrometry is a technique frequently used by scientists to determine the identity and properties of an unknown substance. It is based on the principle that particles flying through a magnetic or electric field will separate based on their size.
Organic compounds in particular, such as amino acids and sugars, have unique signatures on mass spectrometers. These are the basic compounds of life on Earth and, presumably, they would be on Mars as well.
Mars, one of the four "terrestrial planets," has a metal core and rocky surface like Earth. By studying Mars' history and current biological makeup, researchers hope to gain a better understanding of how life started on Earth. Results will also indicate how habitable Mars is today.
Cotter, also a professor at the School of Medicine, does not believe his miniature spectrometer is a one-trick pony. He claims it also can act as a powerful diagnostic tool that could someday be used in clinical work or other scientific research.
