Nasa scientists now came up with the plan of building an ambitious submillimeter-wave or radio instrument to study plumes of water and organic molecules from the south pole of Saturn’s small moon, Enceladus.
In this mission, they are likely to involve the Submillimeter Enceladus Life Fundamentals Instrument or SELFI. SELFI is the remote-sensing instrument that represents an essential improvement over the existing state-of-the-art in submillimeter-wavelength devices.
The instrument will measure footprints of chemicals within plumes of water vapor and icy particles on Enceladus. Studying them, scientists believe that they will hypothesize the composition of the ocean that lies beneath the moon’s icy crust and its potential to host extraterrestrial life.
Since Cassini mission entered the Saturn system, Enceladus has become a major source of interest. When scientists discovered that the plumes continuously tend to eject particles, water vapor, carbon dioxide, methane, and other gases, they thought Enceladus was frozen solid. Once the probe detected plumes of water and organic molecules erupting from the moon’s southern polar region, scientists began to speculate that Enceladus may possess a warm-water ocean in its interior.
SELFI Principal Investigator Gordon Chin said, “Submillimeter wavelengths, which are in the range of very high-frequency radio, give us a way to measure the quantity of many different kinds of molecules in a cold gas. We can scan through all the plumes to see what’s coming out from Enceladus. Water vapor and other molecules can reveal some of the ocean’s chemistry and guide a spacecraft onto the best path to fly through the plumes to make other measurements directly.”
“Molecules such as water and carbon monoxide, and others, are like little radio stations that broadcast on very specific frequencies that say, ‘hey, I’m water, I’m carbon monoxide. A submillimeter spectrometer sensitive to these wavelengths is like tuning to a radio station with a specific molecular call-sign.”
With its increased sensitivity with an amplifier, scientists want to boost the signal in the region around the 557 GHz frequency that has the strongest signal from the water. They believe that this will improve the ability to measure even vanishingly small quantities of water and traces of other gases, even at the cold temperatures.
Scientists reported SELFI can potentially detect and analyze 13 molecular species, including water in various isotopic forms as well as methanol, ammonia, ozone, hydrogen peroxide, sulfur dioxide, and sodium chloride, the table salt chemical that makes Earth’s oceans salty.
Chin said, “SELFI is really new. We can sufficiently improve the instrument to propose for a future mission. This is one of the most ambitious submillimeter instruments ever built.”