Exam 15: Astrobiology

Modern laboratory experiments that repeated those of Urey and Miller in exploring the possibility of producing organic molecules (the building blocks of life)from mixtures of gases expected to exist in the early planetary system passed electrical discharges through which mixture of gases?

One of the great lessons being learned from modern astronomy is that:

What do the letters SETI stand for?

In what way does the Drake equation combine the various factors (e.g.,fraction of stars with planets,fraction of planets that can support life)in an attempt to determine the number of technically advanced civilizations existing elsewhere in the Milky Way Galaxy?

In the search for intelligent life,why do scientists tend to assume that its biochemistry is more likely to be based on the element carbon than on any other element?

Which event of the past century do you think will have announced our presence on Earth MOST effectively to extraterrestrial watchers?

What is the current status of our search for inhabitable,Earthlike planets circling other stars?

The earliest searches for radio signals from extraterrestrial civilizations were made about:

What strategies and electromagnetic frequencies are thought to be the MOST logical for long-range communication across the universe with other intelligent beings?

Carbon is considered the most likely element upon which life chemistry could be based because it satisfies many requirements,three of which are listed below.Which requirement is NOT considered useful in life chemistry?

Part of determining the Drake factor R* is determining what is a "Sun star," a star around which a habitable planet could orbit.What is the thinking concerning low-mass stars,that is,stars with masses less than about half a solar mass? (These are stars cooler than M0 type main-sequence stars.)

It is unlikely that planets near stars much more massive than the Sun would develop life because:

What conditions restrict the suitable wavelength range for communication with extraterrestrial intelligence to the "water hole" in the high-frequency radio range of the electromagnetic spectrum (see Figure 15-8 of Comins,Discovering the Essential Universe,6th ed.)?

At the present time,the search for extraterrestrial life in the solar system has been concentrated on a few bodies.These bodies do NOT include:

One of the important numbers in determining how many extraterrestrial civilizations there may be at the present time in the Milky Way Galaxy is the following: Out of the stars that have planets,what fraction,fs,has planets suitable for life? (This number is similar to the number nₑ in the Drake equation.)Based on the extrasolar planets already found by astronomers (see Chapter 5 of Comins,Discovering the Essential Universe,6th ed.),what is a good guess for fs? (Note: If all stars with planets have at least one planet suitable for life,then fs = 1; if no such star anywhere in the Milky Way has a planet suitable for life,then fs = 0.)

Around which types of stars are we MOST likely to find planets supporting our kind of life?

The estimates in the Drake equation are not constant but evolve over time based on increased observational evidence.Because of the discovery of over a thousand extrasolar planets,the text chose the value fp = 1 for the fraction of Sunlike stars that have planets.What would you suppose Drake chose for this parameter in 1960?

The first successful detection of signals from extraterrestrial civilizations was accomplished in which year?

It is unlikely that intelligent life would develop on a planet circling a star of significantly less mass than the Sun because:

The numerical value given by the Drake equation: