Deck 8: Looking for Life Beyond Earth

Question 1

An extraterrestrial alien spacecraft crashed near Roswell,New Mexico,in 1947.

Answer 1

False

Question 2

One-third to one-half of Americans believes that UFOs continue to visit Earth from distant,alien worlds.

Answer 2

True

Question 3

The tidal forces from Jupiter cause flexing in the interior of Europa that generates enough heat to keep subsurface water from freezing.

Answer 3

True

Question 4

Scientists used a radioactive age-dating technique to determine that the SNC meteorites are much younger than the age of the solar system.

Question 5

The Miller and Urey experiment used molten metal to simulate volcanic lava on the primordial Earth.

Question 6

A carbon atom can bond to four other atoms and can form complex molecules.

Question 7

The Miller-Urey experiment demonstrated that extrasolar planets exist.

Question 8

Besides Earth,the planet most likely to have had the right conditions for the origin of life is Mercury.

Question 9

Evidence suggests that planetary formation around stars like the Sun are very uncommon.

Question 10

The Viking Landers spacecraft carried out three different tests looking for evidence of Martian microorganisms.

Question 11

Astrobiology is the study of life in the universe.

Question 12

Humans are the most common form of life on Earth.

Question 13

The Viking Landers found definitive proof of life on the surface of Mars.

Question 14

Astronomers have carried out a number of searches for signals from other stars in the X-ray band of the electromagnetic spectrum.

Question 15

A large part of NASA's funding currently goes toward the SETI program.

Question 16

Surveys show that 3% to 5% of Americans believe UFOs visit Earth from alien worlds.

Question 17

ALH 84001 is the only known specimen of a rock that was on Mars during the era when liquid water most likely existed on the planet's surface.

Question 18

On Earth,gray hematite is found in places where water exists or has exited in the past.

Question 19

A project called SETI@home uses a data analysis program that acts as a screensaver so volunteers can have their personal computers analyze data when they are not using them.

Question 20

The most uncertain variable in the Drake equation is the rate at which solar-type stars form in the Galaxy.

Question 21

The SNC meteorites are

A) granitic rocks from Venus.
B) rocks discovered on Earth whose origin has been traced to Mars.
C) basaltic rocks from the center of a volcanic caldera on the Moon.
D) carbonaceous chondrites from the asteroid belt.

Question 22

The Viking Landers pyrolytic-release experiment,which was used to look for life on Mars,was based on the idea that in

A) respiration,organisms take in some gases and release others,thus altering the composition of the atmosphere around them.
B) photosynthesis,gases are removed from the atmosphere and incorporated into the organism.
C) running around a maze,an organism's heart rate goes up.
D) metabolism,organisms consume nutrients from the soil and produce gases as a by-product.

Question 23

Why are search strategies for extraterrestrial life usually based on a carbon chemistry?

A) Carbon dioxide is the main ingredient of planetary atmospheres,both terrestrial and Jovian.
B) Carbon is abundant and is versatile in forming complex,long-chain molecules.
C) Most meteorites that reach Earth are composed of carbon.
D) No other atom can combine easily with the abundant hydrogen and helium to form long molecules in interstellar gas.

Question 24

Evidence of water on Mars during its ancient past includes all of the following EXCEPT one.Which is the exception?

A) The polar caps appear to contain large amounts of frozen water.
B) Minerals observed by Opportunity on the Martian surface are those generally formed in a liquid environment.
C) Some of the landing areas resemble dry lake beds.
D) Shallow pools of liquid water have been discovered on a portion of the Martian surface where temperatures remain above freezing.

Question 25

The exploratory life-sciences experiments on board the Viking Landers spacecraft found evidence

A) of reactive chemistry in the Martian surface rocks,but no evidence of life or remnants of life forms.
B) of a sterile environment in which life could not have existed,probably sterilized by intense solar UV radiation,and a chemically inert soil,reacting with almost no reagents.
C) of primitive life forms such as elementary bacteria,which should not be a hazard when humans explore Mars.
D) that primitive life forms had existed on Mars earlier in its history,but they did not survive.

Question 26

Where have some scientists hypothesized that they have found direct evidence for life,either contemporary or ancient,beyond Earth (although the hypothesis has been strongly disputed by many other scientists)?

A) In "orange soil" found on the Moon
B) In spectra of the dark deposits along fissures in the ice of Jupiter's satellite,Europa
C) In the "soil" (regolith)at the Viking 2 landing site on Mars
D) In a meteorite composed of ancient Martian rock

Question 27

The Drake equation attempts to predict the

A) probability that primitive life exists elsewhere in our Galaxy.
B) number of inhabitable planets around stars in our Galaxy.
C) number of technologically advanced civilizations in our Galaxy.
D) number of intelligent civilizations in the universe.

Question 28

In the "meteorite" AL 84001,recovered from Antarctica and traced to an origin on Mars,which of the following,indicating the possibility of life on that planet,has NOT been found?

A) Rounded grains of carbonate minerals,which can be produced by life forms
B) Magnetite and sulfide compounds,found together in carbonates,a sign of bacterial action
C) Enclosed pockets of carbon dioxide (CO₂)and methane (CH₄),which were most likely produced by life forms
D) Elongated tube-like structures,resembling fossilized microorganisms

Question 29

The first person to look for radio signals from extraterrestrial civilizations was

A) Arno Penzias.
B) Frank Drake.
C) Martin Schwarzschild.
D) Jocelyn Bell.

Question 30

The Viking Landers labeled-release experiment,which was used to look for life on Mars,was based on the idea that in

A) photosynthesis,gases are removed from the atmosphere and incorporated into the organism.
B) running around a maze,an organism's heart rate goes up.
C) respiration,organisms take in some gases and release others,thus altering the composition of the atmosphere around them.
D) metabolism,organisms consume nutrients from the soil and produce gases as a byproduct.

Question 31

To what do the letters SETI refer?

A) Sourcebook of Extrasensory Transient Incidents
B) Search for Extra Terrestrial Invaders
C) Search for Evidence of Terrestrial-planet Inhabitants
D) Search for Extra Terrestrial Intelligence

Question 32

The meteorite ALH 84001 was discovered in Antarctica in 1984.Some researchers claimed that it came from Mars and that it showed fossilized evidence of life.At the present time,the scientific community is in general agreement that this meteorite

A) came from Mars.
B) contains fossilized life forms.
C) does not contain fossilized life forms.
D) came from Mars and contains fossilized life forms.

Question 33

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,etc. )in an attempt to determine the probability of life existing elsewhere in the Galaxy?

A) It takes the product of all the factors.
B) It takes the sum of each of the factors.
C) It divides the sum of three factors by the sum of the other four factors.
D) It subtracts the sum of six factors from the initial factor,the rate of solar-type star formation.

Question 34

Which of the following was found in the laboratory container after Urey and Miller had exposed a mixture of hydrogen,ammonia,methane,and water vapor (typical chemicals in the atmospheres of outer planets)to an electric arc (to simulate lightning)for a few days?

A) DNA and RNA molecules
B) Amino acids
C) Aqueous crystals of numerous salts of compounds of nitrogen,oxygen,and carbon
D) Viruses

Question 35

What do we estimate for the time delay between when ALH 84001 was blasted from the surface of Mars and when it landed in Antarctica?

A) Only a few months
B) About a year
C) Millions of years
D) Almost 4.5 billion years

Question 36

The classical laboratory experiments performed by Urey and Miller in order to explore the necessary conditions for the production of organic molecules (the building blocks of living things)in the solar system involved the passing of electrical discharges through what mixture of gases?

A) Hydrogen and helium
B) Carbon dioxide,water vapor,and dust
C) Nitrogen,oxygen,water vapor,and carbon dioxide
D) Ammonia,methane,water vapor,and hydrogen

Question 37

Scientists are now targeting Europa,one of Jupiter's moons,as a likely site to search for elementary life forms because

A) radio signals that follow a recognizable pattern have been detected from this moon.
B) there is strong evidence for liquid water beneath the thick ice layer on its surface.
C) changes have been seen in the dark lines crossing the icy surface which have a spectral signature of vegetation.
D) there appears to be large amounts of dark organic material spread on its surface.

Question 38

In the Drake equation for estimating the possible number of technically advanced civilizations in our Galaxy,the factor for the rate at which solar-type stars form in a galaxy excludes massive stars with masses greater than about 1.5 times that of the Sun.Why?

A) Such stars never develop a nuclear furnace in their interiors and hence can never heat any planet sufficiently to sustain life.
B) These stars would never develop nuclear processes that could produce heavy elements (e.g. ,iron)for ejection outward to form planets such as Earth.
C) Such stars are prone to repeated and violent supernova explosions,which would destroy any developing life forms.
D) Such stars have lifetimes shorter than it took for intelligent life to develop on Earth,and hence should probably not be considered.

Question 39

How have we been able to obtain samples of Martian rocks?

A) Rocks have been collected and returned from the Moon to Earth by astronauts,now identified as Martian rocks blasted from that planet by a massive impact.
B) Rocks have been blasted off Mars by impacts,and have landed on Earth as meteorites.
C) We have not yet been able to obtain any Martian rock samples.
D) Sample return missions have been flown in which a robotic rover collected rocks and returned them to Earth.

Question 40

The Viking Landers gas-exchange experiment,which was used to look for life on Mars,was based on the idea that in

A) metabolism,organisms consume nutrients from the soil and produce gases as a by-product.
B) respiration,organisms take in some gases and release others,thus altering the composition of the atmosphere around them.
C) photosynthesis,gases are removed from the atmosphere and incorporated into the organism.
D) running around a maze,an organism's heart rate goes up.

Question 41

Probably the most difficult factor to estimate in the Drake equation is

A) R_*,the rate at which solar-type stars form in the Galaxy.
B) f_p,the fraction of stars that have planets.
C) n_e,the number of planets per solar system that are Earthlike (suitable for life).
D) L,the lifetime of a technologically advanced civilization.

Question 42

What are the parameters that limit the choice of wavelength for possible communication with extraterrestrial intelligence to the "water hole" in the high-frequency radio range of the electromagnetic spectrum ?

A) Cosmic background radio noise at low frequencies and radio noise from the Sun and Jupiter at high frequencies
B) Local radio noise from TV,radio,and aircraft across the band,except a narrow range in which transmission is prohibited by international agreement in order to permit such extraterrestrial communication
C) Atmospheric absorption by the ionosphere at low frequencies and by CO₂ at high frequencies in the long infrared range
D) High galactic radio background noise at low frequencies and high atmospheric absorption by H₂O and O₂ at high frequencies

Question 43

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

A) Red-giant stars
B) Low-mass,main-sequence stars
C) Very-low-mass stars
D) High-mass,main-sequence stars

Question 44

The so-called "water hole" is a range in the electromagnetic spectrum in which searches for transmissions of extraterrestrial origin are being conducted.In what region of the electromagnetic spectrum does the "water hole" occur?

A) Ultraviolet
B) Visible
C) Infrared
D) Microwave

Question 45

NASA's Kepler mission has been successful in finding

A) thousands of planets.
B) millions of galaxies.
C) life on Mars.
D) hundreds of sunspots.

Question 46

Which of the following has placed Martian rocks in the hands of scientists on Earth?

A) A rover on Mars sent a sample back to Earth.
B) A sample return mission by the former Soviet space exploration program.
C) Rocks brought back by astronauts from the Moon whose Martian origin was established by their chemical makeup and red color.
D) Meteorites collected from Antarctica,the gases within them indicating that they were blasted from Mars by an impact.

Question 47

In what way is the SETI@home program helping to search for radio signals from intelligent life forms elsewhere in our universe?

A) More than a million personal computers analyze data from radio telescopes sent to them from the University of California when otherwise these computers would sit idle.
B) Thousands of people with satellite dish antennas for TV reception have donated time on their receivers to collect radio signals from selected regions of space.
C) Thousands of dedicated amateur astronomers are each spending hundreds of hours searching the space around nearby stars suspected of having planets,looking for bright flashes from possible nuclear explosions on these planets.
D) Hundreds of people are using their cell phones to listen for extraterrestrials.

Question 48

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

A) such a planet would need to be very close to the star and would become tidally locked to the star,making one side of the planet too hot and the other side too cold.
B) the lifetime of such a star on the main sequence is too short;life forms on such a planet would not have time to evolve to a sufficient level of intelligence.
C) there would be no region around the star where UV,visible,and IR light intensities would be suitable for the evolution of life.
D) no moon would form around a planet near such a star,and a moon is considered essential for the evolution of life because of tidal variations on the shorelines of Earth.

Question 49

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

A) Night-by-night photography of nearby stars at hydrogen wavelengths
B) X-ray surveys of space at appropriate times (e.g. ,when Earth is closest to nearby stars in its orbit),in view of the penetrability of space at these wavelengths.
C) Explosion of nuclear devices at specific intervals and in specific patterns across Earth when it is closest to a nearby star
D) Continuous radio and microwave monitoring at specific frequencies at which the sky noise is low

Question 50

If we succeed in detecting signals from other civilizations in space,what method of communication will prove to be the fastest?

A) Neutrinos,because a beam of these particles,suitably modulated,can be made to travel almost infinitely fast because they can penetrate almost anything very easily
B) Nuclear-powered rockets,because we can then use unlimited power to accelerate these systems to almost infinite speeds
C) Laser light,because this single-wavelength light can be directed into an extremely narrow and intense beam and can therefore be made to travel much faster than ordinary light
D) It does not matter what is used because the speed of light can never be exceeded by anything in our universe,thereby setting the communication speed limit.

Question 51

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

A) Two stars have now been discovered with an Earth-mass planet orbiting at distances suitable for liquid water and life,but we cannot yet determine whether they have oxygen-rich atmospheres.
B) Planets have been detected orbiting other stars,but none appear to be suitable for life.
C) No extrasolar planets of any kind have yet been confirmed.
D) Several planets have been found with a mass similar to that of Earth,but they are either too close to or too far away from their star to have liquid water or life on their surfaces.

Question 52

Kepler is an orbiting telescope and was designed to search for Earth-sized planets.Which one of the following statements about Kepler is NOT true?

A) Planets,to be detected,must be in orbits more or less edge-on as viewed from Earth.
B) Kepler will search for the wobble of a star caused by an orbiting planet.
C) The dimming of distant stars as planets pass in front of them (which Kepler will do)has,in fact,been observed for relatively large planets.
D) Kepler will be able to monitor thousands of planets at once.

Question 53

What is the primary reason why a star of twice the mass of the Sun is considered an unlikely candidate for having an extraterrestrial civilization?

A) It is too hot and emits too much ultraviolet radiation.
B) The star's gravity is too strong.
C) Its main-sequence lifetime is too short.
D) Planets would form too close to it.

Question 54

For which of the following factors in the Drake equation do we actually have observational knowledge,rather than just a speculative estimate?

A) R_*,the rate at which solar-type stars form in the Galaxy
B) f_l,the fraction of Earthlike planets on which life actually arises
C) f_i,the fraction of life forms that evolve into intelligent species
D) f_c,the fraction of intelligent species that develop adequate technology and then choose to send messages out into space

Question 55

"Darwin," a space telescope system to be launched sometime after the year 2015,will consist of

A) two spacecraft launched in opposite directions to visit a succession of solar-type stars over the next 2500 years and return images of all planets that they find.
B) four 40-m-diameter radio telescopes equally spaced in orbit around the Sun,acting as a radio interferometer 1.25 AU in radius.
C) a single 16-m-diameter telescope designed to image planets around other stars at optical and infrared wavelengths.
D) three 3-m-diameter telescopes linked together as an infrared interferometer.

Question 56

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

A) planets would have to be too close to these cool stars in order to be sufficiently warm for life to evolve,and they would become tidally linked,resulting in no night and day.
B) there would be no region around the star where UV,visible,and IR light intensities would be suitable for the evolution of life.
C) no moon would form around a planet near such a star,and a moon is considered essential for the evolution of life because of tidal variations.
D) these stars would have evolved to red giant or even supernova stages before life could evolve.

Question 57

A single carbon atom can bond to

A) one other atom,producing diatomic atoms.
B) two other atoms,forming linear molecules.
C) four other atoms,making complex organic chains.
D) six other atoms,making molecular rings.

Question 58

Scientists are now targeting Europa,one of Jupiter's moons,as a likely site to search for elementary life forms because

A) there is strong evidence for liquid water beneath the thick ice layer on its surface.
B) large amounts of dark organic material appear to be spread on its surface.
C) changes have been seen in the dark lines crossing the icy surface that have the spectral signature of vegetation.
D) a methane atmosphere suggests life forms currently living there.

Question 59

Why will proposed future experiments to search for Earthlike planets use the infrared region of the spectrum?

A) Life forms give off IR radiation preferentially when they are alive (and warm!).
B) The ratio of IR to visible radiation from planets is much higher than for their parent stars.
C) Earth's atmosphere is more transparent over this wavelength range than at any other wavelength.
D) Only at these wavelengths will spectra show spectral signatures that are identifiable as originating on Earthlike planets.

Question 60

The Drake equation calculates the possible number of

A) technically advanced civilizations with whom we could communicate in the entire universe.
B) planets in our Galaxy on which life has evolved.
C) technically advanced civilizations with whom we might communicate in our Galaxy.
D) intelligent civilizations that have already died out.

Question 61

How is it possible that we have a rock from Mars on Earth?

A) Astronauts traveled to Mars and brought back a sample.
B) Robotic spacecraft have traveled to Mars and sent back a sample.
C) A large impact ejected some pieces of Mars and they got caught in Earth's gravitational pull and landed on Earth.
D) There are no rocks from Mars on Earth.

Question 62

A key test that will make sure that the dimming of light from a star is caused by a planet as detected by the Kepler is that the dimming would

A) repeat with a definite period.
B) occur simultaneously with multiple systems at the same time.
C) be at least half of the brightness of the star.
D) be confirmed with ground-based telescopes.

Question 63

Which of the following did NOT study Mars?

A) Curiosity
B) Spirit
C) Opportunity
D) LCROSS

Question 64

The most uncertain variable in the Drake equation is

A) the rate at which solar-type stars form in the Galaxy.
B) the fraction of stars that have planets.
C) the fraction of planets per solar system that are Earthlike.
D) involving the longevity of a civilization.

Question 65

The first person to tackle the issue of determining how many technologically advanced civilizations are in the Galaxy was

A) David McKay.
B) Everett Gibson.
C) Stanley Miller.
D) Frank Drake.

Question 66

Kepler,the orbiting telescope,looks for

A) the infrared signature of the planet.
B) the "wobble" that a planet produces in the parent star.
C) the temporary dimming of the light we see from a star as a planet transits it.
D) atmospheric spectra from a planet.

Question 67

The proposed Darwin telescope will be analyzing

A) radio signals.
B) X-ray emissions.
C) infrared spectra.
D) ultraviolet pulses.

Question 68

For an astronomer,what is the "water hole"?

A) A range of noise-free frequencies near the 21-cm emission line of hydrogen
B) A gathering place after scientific conferences
C) A range of noise-free frequencies between the microwave emission lines of hydrogen and hydroxyl
D) A hole in the atmosphere through which a spectral signature for water can be detected

Question 69

Why will proposed future experiments to search for Earthlike planets use the infrared portion of the spectrum?

A) Earth's atmosphere is more transparent over this wavelength range than at any other wavelength.
B) Only at these wavelengths will spectra show spectral signatures that are identifiable as originating on Earthlike planets.
C) The ratio of IR to visible radiation from planets is much higher than for their parent stars.
D) It is the easiest spectral range to study from ground-based telescopes.

Question 70

How was Kepler able to find hundreds of planets in a relatively short amount of time?

A) It was constantly scanning the entire sky.
B) It was continuously monitoring a small area of sky containing thousands of stars.
C) It was able to magnify the view enough to visibly see the planets.
D) It hasn't actually found any planets yet.

Question 71

The most common forms of life on Earth are

A) birds.
B) plankton and bacteria.
C) fish.
D) humans.

Question 72

For a planet to transit a star,its orbital plane must be oriented

A) parallel to the galactic plane.
B) edge-on to our line of sight.
C) perpendicular to the ecliptic.
D) It doesn't matter how the orbital plane is oriented.

Question 73

Water (or water ice)has been recently found on each of these bodies EXCEPT

A) Europa.
B) the Moon.
C) Venus
D) Mars.

Question 74

One proposed mission design for the European Space Agency's Darwin telescope is to make use of

A) high-powered lasers.
B) interferometry.
C) adaptive optics.
D) active optics.

Question 75

The rover Opportunity photographed sand dunes on Mars,which showed the presence of millimeter-sized spheres of gray hematite.Why was this an important finding?

A) Such spheres naturally form in water-soaked deposits.
B) It shows that this rare form of iron can occur naturally.
C) Hematite only forms in the presence of bacteria.
D) They must have been produced in the clouds and fell from the sky.

Question 76

Based on statistical studies of star formation in the Milky Way,some astronomers estimate the rate at which a Sun-like star forms in the Galaxy is

A) 1 per year.
B) 1000 per year.
C) 1 million per year.
D) 1 billion per year.

Question 77

All organic molecules found in living organisms are composed of

A) carbon dioxide crystals.
B) backbones of carbon atoms.
C) alternating hydrogen and oxygen atoms.
D) phosphorous and carbon monoxide lattices.

Question 78

A region of the microwave spectrum is called the "water hole" because

A) it is an atmospheric window.
B) water is required for life as we know it.
C) it has within it H and OH,which together make H₂O or water.
D) it is named after Daniel Water.

Question 79

The Viking Landers performed experiments on Mars to look for evidence of Martian microorganisms.The one that was NOT performed was the

A) gas-exchange experiment.
B) water-transpiration experiment.
C) labeled-release experiment.
D) pyrolytic-release experiment.

Question 80

Carbon monoxide can be found in abundance within

A) the meteorites found in Antarctica from the surface of Mars.
B) the subsurface oceans of Jupiter's moon,Europa.
C) giant interstellar clouds that lie along the spiral arms of our Milky Way Galaxy.
D) the ice found in dark craters on the Moon.