Most of this material was developed for the Live From Mars
project by Passport to Knowledge.
Live From Mars was a precursor to Mars Team Online.
During the '96-'97 school year, classrooms were invited to submit answers
to the Challenge Questions below. Though we are no longer accepting answers,
we hope you will find these questions entertaining and challenging.
Students can also make up their own Challenge Questions for each other.
These are known as Student Stumpers and examples can be found in the
What five features make Mars most like Earth? And, what five features
make Mars most unlike Earth?
We hope students will come up with some geologically correct answers,
but also with some clever, provocative and tongue-in- cheek comparisons!
- atmosphere: though Mars' is much thinner than Earth's
- weather: Mars has frost, clouds, but in the current epoch no "precipitation"
- channels that seem to have been carved by running water
- Grand Canyon and Vallis Marineris
- Earthquakes and Marsquakes
- impact craters
- night and day
- fossil evidence of past life (this will only be accepted if students
say it's "definite" for Earth, "possible" for Mars, reflecting continuing
scientific debate about what the features in ALH 84001 really mean!).
See below, Different!!!
- liquid water
- plate tectonics: though there are Marsquakes, the mighty volcanoes
show that the crust has sat over long-lived lava hot spots, rather than
riding over them, and forming features like the chain of islands we
know as Hawaii
- no ozone layer on Mars protecting the surface
- no large, surface life (plants/animals) on Mars compared to Earth
- Mars' day and year are longer than Earth's
- Vallis Marineris was formed by rifting, not carved by a river, as
was the Grand Canyon
- fossil evidence of past life (but this will only be accepted if students
say it's "definite" for Earth, "possible" for Mars, reflecting continuing
scientific debate about what the features in ALH 84001 really mean!)
See above, Alike!!! - no students participating in Live From Earth
BRUSH UP ON YOUR GREEK!
There is a letter of the Greek alphabet that is very important both to
launching NASA's current Mars missions and to getting to Mars. What is
that letter? Also, explain how it is used.
Both Mars Pathfinder and Mars Global Surveyor were launched aboard Delta
II rockets from Cape Canaveral. "Delta V" is what rocket scientists call
the "change in velocity" that keeps a spacecraft on course for a distant
planet. Trajectory correction maneuvers fine tune the route by a combination
of precise timing, and carefully controlled "burns" providing additional
velocity in specific direction.
GO TELL IT ON THE MOUNTAIN
Olympus Mons is the highest feature on Mars. What is its counterpart on
Earth? Be forewarned: it is not Mount Everest! If you think about how
astronomers measure the height of features on Mars, you'll have a clue
to help this question. What do we mean?
If you measure Mauna Kea, Hawaii, from ocean floor to peak, you will find
that it is higher than Mt. Everest, Nepal -- about 30,000 feet compared
to Everest's 29,000 feet.
For Mars, astronomers use the "datum level" -- the reference surface
at which atmospheric pressure is 6.1 millibars (the pressure at the
triple point of water) -- to give a baseline for measurement of altitude.
On Earth we use sea level, but that would currently be impractical to
do on Mars -- though some astronomers think there may once have been
an ocean on Mars, or at least lakes of liquid water, now lost to space
or locked in permafrost.
If you discount Earth's OCEANS, then the surface area of Earth and Mars
-- the dry land of Earth and the surface area of Mars -- are almost the
same. (509,600,000 km squared) (Source of surface area: The Cambridge
What do we mean when we say that "this feature" may make Earth unique
when compared to other planets (but maybe not the moons) in our solar
Many astronomers think that Jupiter's moon Europa may hide an ocean
of liquid water under an icy crust, making it the only body in our solar
system, apart from Earth, with liquid water. The Galileo spacecraft
is continuing its successful exploration of the Jovian system, and has
seen what looks like pack ice, forming then breaking up and reforming
in characteristic patterns.
WHO ARE THEY?
Mars has always been a place that has engaged our imagination, as well
as our scientific curiosity. In the 19th and 20th centuries two men with
almost the same last name created the exact same titles in two different
media. Who were these men and what did they write and produce?
In 1898 H.G. Wells wrote the 17-chapter novel "The War of the Worlds."
Forty years later, Orson Welles adapted the novel for radio and on the
night before Halloween in 1938, he starred in a radio drama by the same
name. This began the most stunning single program ever broadcast on radio.
It set off a wave of mass hysteria as Welles described in breathless radio
news bulletins and on-the- scene reports that Martians had invaded New
Jersey. Even though CBS made four announcements during the radio show
that it was "only a play," may listeners did not year them. Panic swept
through New Jersey as people fled their homes and covered their faces
with wet handkerchiefs to protect themselves from the reported poison
If geology is the study of the Earth (from the Greek geo-earth and logos-knowledge)
what should we properly call the study of Mars?
Your answer can be either etymologically correct, with Greek derivation,
or more humorous if you like!
Areology - Ares is Greek for Mars, just as Geos is the Greek word for
Earth. (Remember Pathfinder will land in Ares Vallis, the Valley of Ares.)
Dave Bogan -- 8th grader at Taylor Road Middle School -- Alpharetta, Georgia
-- gave the exact answer!
Honorable Mention: Matt Bohnhoff and MESA Class of Provo, Utah.
The Mars Global Surveyor (MGS) took off in November and is scheduled to
arrive at Mars between Sept. 11 and Sept. 22, 1997. The Mars Pathfinder
(MPF) takes off sometime in December. No matter when it leaves, it is
scheduled to arrive on July 4, 1997.
Why does the Pathfinder get to Mars earlier, even though it leaves
And how can the Pathfinder have an exact arrival date even though
its liftoff date may vary?
Answer from Cheick Diarra:
There are several reasons for Pathfinder's earlier arrival at Mars. Pathfinder
is much smaller and lighter than Mars Global Surveyor. As a result, the
rockets sending it to Mars can get it going at a faster velocity. Also,
Pathfinder goes on a much more direct route to Mars than MGS, which takes
a longer, more looping path. So not only is MPF going faster, it has less
miles to travel.
There is a good reason for MGS's more looping path. The arrival velocity
depends on the type of trajectory. The more looping trajectory provides
a slower arrival velocity. Since MGS is an orbiter, NASA wants it to
arrive at Mars with as little speed as possible. This is because it
will need to be slowed down with a retro burn to be captured by Mars's
gravity. That maneuver is called the Mars Orbit Insertion maneuver,
or MOI for short. The slower MGS is going relative to Mars, the smaller
the retro burn. And a smaller retro burn means less fuel (and weight
and dollars). So that is why MGS is on a more looping trajectory which
will allow for a slower arrival speed. MPF, on the other hand, is not
going into orbit, so it can arrive at a faster speed, and thus its more
direct route to Mars.
To help understand why a more looping trajectory results in a slower
arrival speed, consider a golf ball being putted on a slanting green
toward the hole. A golfer can hit the ball hard right toward the hole
and the ball will arrive relatively quickly. Or else, the ball can be
putted more gently toward the uphill side of the hole; in that case,
the ball will loop down towards the hole and arrive at a slower speed.
Finally, about the issue of the fixed arrival date for MPF. When we
travel to Mars, we have the opportunity to do Trajectory Correction
Maneuvers (TCMs) that let us correct not only our aim point at Mars
arrival but also the time of arrival. Early on, NASA decided July 4
would be a good day to arrive. This was partially historical. In 1976
when the Viking spacecraft went to Mars, it was expected to land on
July 4 for national reasons (July 4 is America's Independence Day).
But when Viking arrived, there was a raging dust storm that prevented
this scheduled landing so the team missed a July 4 landing and decided
to remain in orbit until July 20 (July 20 is the anniversary of the
first Apollo landing). So this time NASA has decided that Pathfinder
should land on July 4. The TCMs for Pathfinder will be performed to
remain true to the July 4 landing date.
The largest crater on the larger of the two Martian moons, Phobos, is
named Stickney. Ms. Stickney was not an astronomer but she played a critical
role in the discovery of the Martian moons. Who was Ms. Stickney and why
did she have this prominent surface feature named after her?
Answer from Bill Gutsch:
The two moons of Mars were discovered by astronomer Asaph Hall at the
US Naval Observatory in 1877. According to the story, after many nights
of searching for satellites that might be in orbit around Mars, Hall was
ready to give up. His wife, however, encouraged him to give it "one more
try." That night, Hall found Deimos and Phobos, the two Martian moons.
In honor of her encouragement, without which Hall might not have made
his discovery, astronomers in the 1970s decided to name the largest crater
on Phobos "Stickney" -- Mrs. Hall's maiden name.
Sometimes the winds on Mars can blow at hundreds of miles per hour and
kick up giant dust storms that blanket the entire planet. Yet, if you
stood on the surface of Mars at one of these times, you would probably
not be blown over. Why?
Answer from from Bill Gutsch:
Martian winds can be swift but the Martian air is so thin that it packs
very little punch. In more scientific terms, this means that there wouldn't
be nearly as many air molecules striking you per second in a Martian wind
storm as there would be in a similar storm on Earth. Far fewer molecules
translates into much less pressure (force per square inch) pushing against
your body. Such "thin winds" can still create giant dust storms, however,
because the Martian surface dust is very, very fine and so can easily
be lifted into the Martian sky.
Mars has two moons: Deimos and Phobos. If you stood on the surface of
Mars and looked up into the night sky, you would see Deimos slowly travel
from east to west across the sky while Phobos would be slowly traveling
from west to east. In other words, the two Martian moons travel in opposite
directions across the Martian sky. Yet both moons actually orbit Mars
in the same direction.
Explain this apparent paradox.
Answer from Bill Gutsch
The closer a satellite (natural or artificial) is to the planet it orbits,
the faster it travels around that planet. Both Martian moons travel around
Mars from west to east. Deimos, however, is sufficiently far from Mars
(like the Earth's moon is from Earth) that it travels around the planet
slower than Mars rotates on its axis. Thus, to an observer on the surface
of Mars, Deimos appears to be "left behind in the sky" and appears to
move from east to west. Phobos, on the other hand, is much closer and
actually orbits around Mars faster than Deimos.
The Valles Marineris is much larger and deeper than the Grand Canyon in
Arizona. Yet, if you stood at the rim of the Valles Marineris, it probably
wouldn't seem as impressive to the eye. Why?
Answer from Bill Gutsch
While the Valles Marineris is big, deep and wide, Mars is a much smaller
planet than Earth. This means that on Mars, the horizon curves out of
the way much closer to you than it does on Earth. The result is that differences
in elevation in surface features are not as impressive. On Earth, for
example, you can stand at the North or South Rim of the Grand Canyon and
see the whole breadth of the canyon -- all the way over to the opposite
rim. In places, however, the Valles Marineris is over 100 miles from rim
to rim. This is so great compared with Mars's tiny size that if you stood
on one rim of the Valles Marineris, you wouldn't be able to see the other
rim because it would be out of sight over the horizon!
Answer from Alan Federman, NASA Ames:
As a first approximation, we need to look at the relevant equation:
Answer from Bryan Glenn:
F = MA: Force is equal to Mass times Acceleration.
The acceleration we are interested in is due to the gravity field
of Mars. Mars gravity is equal to 0.38 of Earth's, so as a first approximation,
the "A" on Mars is .38 * 980 cm/s/s = 370 cm/s/s. If the Force of Gravity
were the only effect on the ball, 410 ft / 0.38 = 1079 feet (or 323
To make the game "play the same," other factors need to be considered.
For example, atmospheric effects. The thin atmosphere means less air
resistance so balls will carry farther. How fast people can run wearing
space suits would also be a problem. Maybe changing the mass of the
players and their equipment is an option.
While rain-outs are not going to be a problem, games may need to be
called on account of wind or sandstorms!
Good Luck, Commish!
The old baseball Commish will have quite a problem on his hands placing
that fence in the right location. There are actually 2 variables he will
have to consider, gravitational differences and atmospheric differences.
Both will have a significant impact, but the latter will be much less
predictable than the first.
When gravitation is compared, Earth's would be +/- 978 cm/sec2, while
Mars's gravitation is estimated at 371 cm/sec2. 978/371 = 2.64, so the
410 ft x 2.64 = 1081 ft. That would seem a mighty drive for anyone if
the two atmospheres were comparable. But they are anything but!
Earth's gravity and Venus's gravity are almost identical, but if we
were putting up a fence on Venus, a 410-ft fence might as well be 2
miles away. Atmospheric pressures on Venus are 100 times that of Earth,
so driving a ball through that layer of carbon dioxide smog would require
a mighty, mighty bat.
Mars's atmospheric pressure is estimated at 0.6% that of Earth's.
Again, some quick calculations should yield the lower atmospheric drag
on the bat and ball to determine the "atmospheric" adjustment. But it
is not so simple; here again we cannot think of this in earthly terms.
The extreme thinness of the atmosphere and the generally colder temperatures
will produce some very "Mars Only" considerations. This thin atmosphere
is easily varied by minor climatic events that would produce far less
change in Earth's heavier atmosphere. Martian temperature changes could
easily produce sudden gusty winds roaring over 100 miles/hour. As winter
approaches and more of the carbon dioxide becomes crystallized at the
poles, the already thin atmosphere will become even thinner. Parks near
the poles will play far differently than those near the Martian equator.
Home runs will be even easier to hit then, unless the ball runs into
an unexpected 200 mile/hr blast of wind on its way to the fence!
Good luck commissioner. Your Martian game will add elements never
dreamed of back on good ol' Earth!