Destination Mars (31 page)

CHAPTER 1. THE FIRST MARTIAN

1
. The Soviet unmanned Mars program was spectacular in its persistence and its failures. While successful with other planets, notably Venus, Soviet-era Mars missions were notorious in their failure rate. Two years prior to the successful landing of Viking 1, in August 1974, the Soviet Mars 6 and 7 entered Martian space. Mars 7 failed before descending, but Mars 6 actually “landed” on the surface of Mars, transmitting a few minutes of data, mostly unintelligible, just prior to touchdown. Since the fall of the Soviet Union, and with increased cooperation with the European Space Agency, the program has seen some shared success. Yet as recently as November 2011, the Russian-led Phobos-Grunt sample return mission to the Martian moon Phobos failed after launch.

2
. Among other things, the lander was baked in swirling clouds of nitrogen gas for over forty hours. The goal was to make sure that no earthly organisms polluted either Mars or the life science experiments. In fact, NASA/JPL had devised an entire program of “planetary quarantine” leading up to this mission. Ironically, in the intervening decades, it has become clear that the Martian environment is so very toxic, with high levels of solar radiation and powerful oxidizing agents present in the soil, that most anything that could have hitched a ride on the lander would have been dead shortly after touchdown.

CHAPTER 2. MARS 101

1
. The “Goldilocks Zone,” also known as the “habitable zone,” is a unique combination of circumstances that must combine (it is thought) for a planet to be able to sustain life. These include: a proper distance from the star it orbits to be able to sustain liquid water on the surface, a size generally similar to Earth's, a star that is not hostile to life-supporting conditions, and a position within the larger galaxy that is not hostile to life (i.e., does not have radiation levels that are deadly to life-forms). This does not necessarily imply that the planet itself can support life. The environment needed to sustain carbon-based life-forms is a different set of conditions and variables. (The name of this zone comes, of course, from “Goldilocks and the Three Bears,” in which Goldilocks tastes three bowls of porridge and rejects two for being too hot or too cold, but determines that the third is just right.)

2
. In the early 1960s, mascons were first encountered by the early unmanned orbiters, whose orbital paths were affected in unexpected ways over certain regions of the moon. They were of much concern to those planning the descent paths of the Lunar Modules, and that was one reason for the “barnstorming” flight of Apollo 10, in which astronauts approached but did not land on the lunar surface. They wished to further explore the effects of these anomalies on descent trajectories.

3
. The “terrestrial” planets in our solar system are, in order from the sun, Mercury, Venus, Earth, and Mars. They are characterized by rocky composition, a solid surface, and roughly similar sizes.

4
. Mars suffers from what is termed
low thermal inertia
, which means that the surface heats quickly in sunlight. There are no oceans present to dampen these effects with clouds or their own weather systems. Martian versions of trade winds can cycle around the planet at very high velocities, though in the thin
atmosphere their effects are not the same as they would be on Earth. Wind velocities of over 100 mph are hypothesized. A 30-50 mph blow can cause dust to lift, often for weeks at a time; higher velocities lift more dust. The chances of a planetwide dust storm in a given year seem to be about one in three.

5
. One such body of theory is called
panspermia.
It proposes that life can survive dormant for long periods in space, hitching a ride aboard a meteor or an asteroid. If the transporting body then impacts another planet, and the conditions are right, it could return to an active state and begin to evolve and adapt. Some propose that life started on Mars and was transported to Earth. And while no direct evidence has yet surfaced, meteors of both lunar and Martian origins have been found on Earth.

CHAPTER 3. IN THE BEGINNING: A SHINING RED EYE

1
. Anonymous source from Middle Ages Europe (ca. approx. 1400 CE), in Willy Ley,
Mariner 4 to Mars
(New York: Signet, 1966).

2
. Retrograde motion can be thought of this way: imagine that you are driving on a racetrack on the inside lane. Mars is driving on the outside lane. For most of the lap, if you take your eyes off what's in front of you and look over at Mars, the background is moving the same direction relative to the planet. However, as you complete your lap (you are moving faster than Mars, about twice as fast), and you approach and pass Mars, it seems to move in the
opposite
direction for a brief period. Now picture Earth's orbit and Mars's orbit outside of it—a similar situation applies. Retrograde motion of Mars appears every two years.

3
. English astronomer, 1860.

4
. Camille Flammarion,
Popular Science
4, no. 9 (December 1873): 189. English translation from the French.

5
. G. V. Schiaparelli,
Osservazioni astronomiche e fisiche
sull'asse di rotazione e sulla topografia del pianeta Marte
, vol. 4 (Rome, Italy: Coi Tipi del Salviucci, 1896).

6
. G. V. Schiaparelli, “Schiaparelli on Mars,”
Nature
51 (November 22, 1894): 89.

7
. John Michels, “Review of ‘Mars’ by Percival Lowell,”
Science
4, no. 86 (August 21, 1896): 233.

8
. Percival Lowell,
Mars
(Boston: Houghton, Mifflin, 1895).

9
. Ibid.

CHAPTER 4. THE END OF AN EMPIRE: MARINER 4

1
. The number of unmanned explorations sent to Mars is nearing forty, yet almost half have been failures. Of these, the vast majority were from the Soviet Union. While successful with many of their missions to Venus, Russian plans for Mars exploration have yielded little success.

CHAPTER 5. D
R
. ROBERT LEIGHTON: THE EYES OF MARINER 4

1
. Dr. Robert Leighton, interview by David DeVorkin, August 5, 1977, Niels Bohr Library and Archives, American Institute of Physics, College Park, Maryland,
http://www.aip.org/history/ohilist74738_1.html
(accessed July 2011).

CHAPTER 7. D
R
. BRUCE MURRAY: IT'S ALL ABOUT THE IMAGE

1
. Dr. Bruce Murray, interview by Rachel Prud'homme, March 1984, courtesy of the Caltech Archives, the California Institute of Technology.

CHAPTER 8. AEOLIAN ARMAGEDDON: MARINER 9

1
. Mariner 9 would be the first of JPL's Mars missions to set the high benchmark to which all now seem to be held. Its primary mission was set at ninety days, just two months longer than the dust storm raged. But the spacecraft sent back images and data for almost a year, extending the mission duration by a factor of four.

CHAPTER 9. D
R
. LAURENCE SODERBLOM: THE EYES OF MARINER 9

1
. Dr. Laurence Soderblom, interview by the author, August 2011.

CHAPTER 10. VIKING'S SEARCH FOR LIFE: WHERE ARE THE MICROBES?

1
. The Soviet Mars missions for the 1973 opposition were Mars 4, 5, 6, and 7. Mars 4 and 5 were orbiters; Mars 6 and 7 were landers. Mars 4 made its way to the planet, but an error in the computer allowed it to flyby the planet as earlier craft had (by design), and the images it returned were a repeat of previous missions. Mars 5 made it to Mars but failed in orbit after less than ten days, returning some data. Mars 6 was a lander, and apparently made it to the surface, albeit at a higher rate of speed than intended. It transmitted data for a few minutes, but the onboard computer seemed to have suffered degradation during the flight and the data returned were unusable. Mars 7 was another lander, but it separated from its carrier spacecraft about four hours early and missed the planet altogether. These four failures must have been even more heartbreaking than most, as they represented a huge investment in time and resources for the Soviet unmanned program. The loss in national prestige cannot be overestimated.

2
.
Utopia Planitia—the
“Nowhere Plain”—sounds like an odd translation to the modern ear. But the translation from the Greek is:
oi
(“not”) and
topos
(“place”) equating “nowhere.” So the modern association of a perfect society does not apply in this case.

3
. The Viking sampler arm was an ingenious design. Rather than carry a heavy, pipelike arm (as later landers have indeed done), the Viking's arms were carried on a spool. It was designed like two giant metal tape measures affixed front-to-front to create an elliptical profile. As the flattened metal tape rolled off the spool, it sprang into the metal's memorized shape and became rigid. It could extend for over ten feet in this fashion and was strong enough to hoist small soil samples upward to the sample containers onboard. This also gave the arm an almost infinite sampling range across its entire length.

CHAPTER 11. D
R
. NORMAN HOROWITZ: LOOKING FOR LIFE

1
. Dr. Norman Horowitz, interview by Rachel Prod'homme, July 1984, courtesy of the Caltech Archives, the California Institute of Technology.

CHAPTER 12. RETURN TO MARS: MARS GLOBAL SURVEYOR

1
. After the loss of the space shuttle
Challenger
in 1986, spacecraft that required an upper stage boost to depart Earth orbit were, in general, rerouted to expendable rockets such as the Delta, Atlas, or Titan.

2
. Hematite is a mineral that we will encounter in our Mars discussions again and again. It is a type of iron oxide, Fe
₂
O
₃
. It is harder than iron but more brittle. Important for Mars explorers,
it is often found in areas that once hosted bodies of standing water, and it can condense out of water. It collects on the bottom of lakes and ponds, and it also can be found near hot springs. Alternatively, it can be found as a result of volcanic activity.

3
. Great noises were made about the “Face on Mars” by some. While generally dismissed by the scientific community upon “discovery,” many wanted to believe—or hope—that it represented a message from an advanced civilization. Even when the improved images came in from MGS, some continued to support this belief. A few have made this into a cottage industry, and significant profits have resulted. This is currently a fringe industry at best.

4
. In the words of JPL's internal review:

Mars Global Surveyor last communicated with Earth on Nov. 2, 2006. Within 11 hours, depleted batteries likely left the spacecraft unable to control its orientation.

“The loss of the spacecraft was the result of a series of events linked to a computer error made five months before the likely battery failure,” said board Chairperson Dolly Perkins, deputy director-technical of NASA Goddard Space Flight Center, Greenbelt, Md.

On Nov. 2, after the spacecraft was ordered to perform a routine adjustment of its solar panels, the spacecraft reported a series of alarms, but indicated that it had stabilized. That was its final transmission. Subsequently, the spacecraft reoriented to an angle that exposed one of two batteries carried on the spacecraft to direct sunlight. This caused the battery to overheat and ultimately led to the depletion of both batteries. Incorrect antenna pointing prevented the orbiter from telling controllers its status, and its programmed safety response did not include making sure the spacecraft orientation was thermally safe.

The board also concluded that the Mars Global Surveyor team followed existing procedures, but that procedures
were insufficient to catch the errors that occurred. The board is finalizing recommendations to apply to other missions, such as conducting more thorough reviews of all non-routine changes to stored data before they are uploaded and to evaluate spacecraft contingency modes for risks of overheating.

“We are making an end-to-end review of all our missions to be sure that we apply the lessons learned from Mars Global Surveyor to all our ongoing missions,” said Fuk Li, Mars Exploration Program manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Jet Propulsion Laboratory, news release no. 2007-040, JPL public affairs office.

CHAPTER 13. ROBERT BROOKS: IT TAKES A TEAM, MARS GLOBAL SURVEYOR

1
. Robert Brooks, interview by the author, September 2011.

CHAPTER 14. ROVING MARS: SOJOURNER, THE PATHFINDER

1
. From JPL's robotics section report on Pathfinder:

The Mobility and Robotic Systems section led the development of both software and electronics for the Sojourner rover. Software enabled autonomous control, sensing, and communication. Onboard autonomy consisted of simple behaviors for navigation, based on commanded objectives along with sensed terrain and vehicle position/ orientation. Terrain sensing was performed with cameras
and laser striping, while Sojourner's position and orientation were measured by wheel odometry, accelerometers, and a z-axis angular-rate sensor. The onboard processor was a flight-qualified Intel 8085 running at 100 KIPS, and all software was written in C.