On Earth, the archaea, which on average measure one micrometer, are much more common and more important for chemical cycles than was long suspected. After all, they don’t absolutely need extreme environmental conditions. They are as common in fresh water as in the sea, where in some areas they represent up to 90 percent of living beings, and in the soil. They also exist as symbionts in the intestinal tract of animals and humans. Archaea have even been found in the human navel. The total number of archaea in the oceans is estimated to be more than 10 to the power of 28, that is, a 1 followed by 28 zeroes. The number of all cells in a human multiplied by the number of human beings is about 10 to the power of 22 (a 1 followed by 22 zeroes), which is six magnitudes smaller.
How Life Might Have Started
We do not know yet whether Enceladus harbors life—but if it does, it must have started at some point in time, either with the chicken or with the egg. We are not sure about what happened afterward, even in the case of Earth. There are two theories about the origin of life that might also apply to Enceladus.
The theory that inorganic molecules in a water-based ‘primordial soup’ randomly combine to form the first organic compounds, and then assemble the most primitive forms of cells, was already suggested by Charles Darwin. In 1953, Stanley Miller and Harold Urey showed in a spectacular experiment how this might have happened on Earth. They had simulated lightning striking a mixture of methane, ammonia, water vapor, and hydrogen. Within two weeks, various amino acids had been created in the solution. These complex molecules form the basic building blocks of life. Miller and Urey were wrong concerning the possible composition of the primordial soup, and they did not create life, but the experiment proved that under the right circumstances complex molecules can be formed from simple compounds. These basic materials and the necessary energy supply in the form of heat are also present on Enceladus, and they have been for billions of years.
At the bottom of Earth’s oceans, hot water, in which various chemicals are dissolved, emerges from the crust of the planet. Some vents eject water with a temperature of almost 500 degrees. These might have been the places where life developed on Earth. The chemical energy provided by the vents in the form of dissolved reduced gases here meets the suitable reaction partners. If such vents exist at the bottom of the Enceladus Ocean, they could also form the starting point for life. After life developed at such hotspots, it could have gradually adapted to cooler environments and spread across the entire ocean.
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Glossary of Acronyms
AI – Artificial Intelligence
API – Application Program Interface; Acoustic Properties Instrument
ASCAN – AStronaut CANdidate
AU – Astronomical Unit (the distance from the Earth to the sun)
BIOS – Basic Input/Output System
C&DH – Command & Data Handling
CapCom – Capsule Communicator
Cas – CRISPR-associated system
CELSS – Closed Ecological Life Support System
CIA – (U.S.) Central Intelligence Agency
COAS – Crewman Optical Alignment Site
Comms – Communiques
CRISPR – Clustered Regularly Interspaced Short Palindromic Repeats
DEC PDP-11 – Digital Equipment Corporation Programmable Data Processor-11
DFD – Direct Fusion Drive
DISR – Descent Imager / Spectral Radiometer
DNA – DeoxriboNeucleic Acid
DoD – (U.S.) Department of Defense
DPS – Data Processing Systems specialist (known as Dipsy)
DSN – Deep Space Network
ECDA – Enhanced Cosmic Dust Analyzer
EECOM – Electrical, Environmental, COnsumables, and Mechanical
EGIL – Electrical, General Instrumentation, and Lighting
EJSM – Europa Jupiter System Mission
ELF – Enceladus Life Finder
EMU – Extravehicular Mobility Unit
ESA – European Space Agency
EVA – ExtraVehicular Activity
F1 – Function 1 (Help function on computer keyboards)
FAST – (Chinese) Five-hundred-meter Aperture Spherical Telescope
FAO – Flight Activities Office
FCR – Flight Control Room
FD – Flight Director
FIDO – FlIght Dynamics Officer
Fortran – FORmula TRANslation
g – g-force (gravitational force)
GBI – Green Bank Interferometer
GNC – Guidance, Navigation, and Control system
HAI – High-Altitude Indoctrination device
HASI – Huygens Atmospheric Structure Instrument
HP – HorsePower
HUT – Hard Upper Torso
IAU – International Astronomical Union
ILSE – International Life Search Expedition
INCO – INstrumentation and Communication Officer
IR – InfraRed
ISS-NG – International Space Station-Next Generation
IT – Information Technology
IVO – Io Volcano Explorer
JAXA – Japan Aerospace eXploration Agency
JET – Journey to Enceladus and Titan
JPL – Jet Propulsion Laboratory
JSC – Johnson Space Center
JUICE – JUpiter ICy moons Explorer
LCD – Liquid Crystal Display
LCVG – Liquid Cooling and Ventilation Garment
LEA – Launch, Entry, Abort spacesuit
LIFE – Life Investigation For Enceladus
LTA – Lower Torso Assembly
MAG – Maximum Absorbency Garment
MCC – Mission Control Center
MIT – Massachusetts Institute of Technology
MOM – Mission Operations Manager
MPa – MegaPascal
MPD – MagnetoPlasmadynamic Drive
MSDD – Multi-station Spatial Disorientation Device
NSA – National Security Agency
NASA – National Aeronautics and Space Administration
NEA – Near Earth Asteroids
PAO – Public Affairs Office
PC – Personal Computer
PE-UHMW – PolyEthylene-Ultra High Molecular Weight
PER – fluid PERmittivity sensor
PI – Principal Investigator
Prop – Propulsion
PSS – Princeton Satellite Systems
RCS – Reaction Control System
REF – REFractive index sensor
RNA – RiboNeucleic Acid
RTG – Radioisotope Thermoelectric Generator
SAFER – Simplified Aid For EVA Rescue
SIRI – Speech Interpretation and Recognition Interface
SFTP – SSH (Secure Socket sHell) File Transfer Protocol