The Interstellar Age (39 page)

at the time the solar system’s most distant known planet
:
For some more details about whether
Voyager
could have encountered Pluto, and other
Voyager
“Frequently Asked Questions,” see the
Voyager
Project’s official FAQ at voyager.jpl.nasa.gov/faq.html.

“fresh” ice in the process
:
It’s a debate that even higher-resolution
Cassini
Saturn orbiter images and other data have yet to resolve.
Cassini
camera team leader Carolyn Porco, who was also heavily involved in
Voyager
imaging of Saturn’s rings earlier in her career, has been careful to note that “there’s a bunch of caveats in all of this. Very little in this area is definite. Each part of the rings may have a different age.” (Porco, as quoted in Richard A. Kerr, “Saturn’s Rings Look Ancient Again,”
Science
319 (2008): 21.) It seems that, once again, we find that we really do have to go back.  .  .  .

rocky lava flow would on Earth
:
A great introduction to cryovolcanism can be found in Rosaly Lopes and Michael Carrol’s book
Alien Volcanoes
(Baltimore: Johns Hopkins University Press, 2008).

the team was confident that everything would go as planned
:
A day-by-day, diary-like account of the details of the
Voyager
Saturn encounters was published by
Voyager
imaging team member David Morrison in
Voyages to Saturn,
NASA Special Publication 451 (Washington, DC: National Aeronautics and Space Administration, 1998) (online at babel.hathitrust.org/cgi/pt?id=uiug.30112012462427). Pages 185 to 189 of that book contain a full list of the principal investigators and co-investigators on the
Voyager
science team and the leaders of the
Voyager
management teams.

“a million times the normal energy level . . .”
:
Fred Scarf, quoted in Morrison,
Voyages to Saturn
, page 123.

almost minute-by-minute account of the Saturn flybys
:
Morrison,
Voyages to Saturn
, page 123.

“The quantity of such impacts . . .”
:
Ibid.

in his diary of events for August 28, 1981
:
Ibid., page 131.

Cassini
orbiter on a “suicide mission” to Saturn
:
Richard C. Hoagland’s original June 30, 2004, article (and his quote) about this can be found online at http://www.enterprisemission.com/_articles/06-30-2004_Cassini/IsNASA SendingtheCassiniMissiontoitsDoom.htm.

“a sense of gloom . . .”
:
Ibid., page 119.

Chapter 6. Bull’s-Eye at a Tilted World

a planetary path, well beyond the orbit of Saturn
:
I recount a lot of the interesting history of William Herschel’s and other pioneering discoveries in astronomy in
The Space Book: 250 Milestones in the History of Space and Astronomy
(New York: Sterling, 2013).

important work cataloguing faint stars
:
A nice article about Caroline Herschel’s life and achievements, including her support of her famous brother’s astronomical discoveries, appears in J. Donald Fernie’s “The Inimitable Caroline” in the November/December 2007 issue of
American Scientist
(online at americanscientist.org/issues/pub/the-inimitable-caroline).

new tilt for a newly formed (potentially merged) planet
:
For a short summary of some of the latest ideas about the strange tilt of Uranus, see John Matson’s October 7, 2011, article “Double Impact: Did 2 Giant Collisions Turn Uranus on Its Side?” in
Scientific American
(online at scientificamerican.com/article/uranus-axial-tilt-obliquity).

“That all of this worked so well . . .”
:
Edward C. Stone and Ellis D. Miner, “The
Voyager 2
Encounter with the Uranian System,”
Science
233 (1986): 39–43.

ten new, smaller moons
:
Wikipedia’s “Moons of Uranus” page, at en.wikipedia.org/wiki/Moons_of_Uranus, is a great resource for history, facts, and additional research links on the twenty-seven presently known moons of the seventh planet.

seems to be a leading hypothesis for what happened
:
Space.com editor and space history author Andy Chaikin posted an excellent article titled “Birth of Uranus’ Provocative Moon Still Puzzles Scientists” on October 16, 2001, summarizing the post-
Voyager
state of confusion regarding the history of Miranda, online at archive.today/6VTxV.

astronomers led by the late Jim Elliot of MIT
:
For a firsthand account of the discovery of the Uranian rings, see Jim Elliot and Richard Kerr,
Rings: Discoveries from Galileo to Voyager
(Cambridge, MA: MIT Press, 1987).

a peer-reviewed scientific journal article
:
My research paper, coauthored with my PhD dissertation advisor, T. B. McCord, is titled “A Search for Spectral Units on the Uranian Satellites Using Color Ratio Images” and was published in the
Proceedings of Lunar and Planetary Science
21 (1991): 473–89 (online at http://adsabs.harvard.edu/abs/1991LPSC...21. 473B).

more complex and dynamic weather
:
For a great summary of the Hubble Space Telescope’s history of imaging of Uranus, check out hubblesite.org/newscenter/archive/releases/solar-system/uranus.

Chapter 7. Last of the Ice Giants

nothing less than solar-system glory
:
In
The Planet Neptune: An Historical Survey before Voyager
(New York: Wiley, 1996), the late Sir Patrick Moore, British astronomer and science popularizer, provides additional stories and details about the history of the discovery of Neptune.

taxpayers of an entire nation
:
For an interesting historical perspective on
Voyager
within the broader context of exploration over the centuries, see Stephen Pyne,
Voyager: Seeking Newer Worlds in the Third Great Age of Discovery
(New York: Viking, 2010).

were found to be roughly ten times smaller
:
Ibid., page 140.

changes in the atmosphere of Neptune over time
:
For a great summary of the Hubble Space Telescope’s history of imaging of Neptune, check out hubblesite.org/newscenter/archive/releases/solar-system/neptune.

entirely new and unanticipated class of planet
:
For a fun and educational conversation about ice giants, check out Planetary Society Weekly Hangout blogger Emily Lakdawalla’s April 11, 2013, interview with
Voyager
imaging team member and Planetary Society vice president Heidi Hammel, online at planetary.org/blogs/emily-lakdawalla/2013/hangout-20130409-heidi-hammel.html.

the entire solar system by nearly 70 percent
:
Just as for all the other planets with moons, Wikipedia is a great resource to learn more about the fourteen moons presently known around Neptune. See en.wikipedia.org/wiki/Moons_of_Neptune.

the low gravity and atmospheric pressure
:
For all the gory details, see “Triton’s Geyser-like Plumes: Discovery and Basic Characterization,” by Larry Soderblom and eight other
Voyager
team colleagues, in the October 19, 1990, issue of
Science
magazine (vol. 250, no. 4979, 410–15).

KBOs, as they are now known, have been discovered
:
The International Astronomical Union’s Minor Planet Center, operated by Harvard’s Smithsonian Astrophysical Observatory, keeps up-to-date lists and graphical plots of the orbits and positions of all the more than 650,000 presently known asteroids and comets in the solar system, including the Kuiper Belt Objects. The lists are online at minorplanetcenter.net/iau/lists/MPLists.html; to see the KBO list, click on “Transneptunian Objects,” the more generic name for KBOs.

New Horizons
spacecraft flies by Pluto in July of 2015
:
Visit the
New Horizons
mission website for more details at pluto.jhuapl.edu.

Chapter 8. Five Billion People per Pixel

human beings who have lived before us
:
The Population Reference Bureau has an excellent online article explaining their estimate for the total number of people who have ever lived on Earth, posted at prb.org/Publications/Articles/2002/HowManyPeopleHaveEverLivedon Earth.aspx.

the White Sands Missile Range in New Mexico
:
Tony Reichhardt, “The First Photo from Space,”
Air & Space
magazine, November 2006 (online at airspacemag.com/space/the-first-photo-from-space-13721411/?no-ist).

after the first Earth-orbiting satellites were launched
:
For more photos and details about these early photos of the Earth from space, see, for example, (a) http://www.nasa.gov/centers/langley/home/Road2Apollo-11_prt.htm; (b) space.com/12707-earth-photo-moon-nasa-lunar-orbiter-1-anniversary.html; (c) moonviews.com/lunar-orbiter-1-i-or-a; and (d) moonviews.com/2013/05/how-life-magazine-revealed-earthrise-in-1966.html.

“Oh my God. Look at that picture . . .”
:
Transcripts of conversations and events from the
Apollo 8
mission can be found in David Woods and Frank O’Brien, “The
Apollo 8
Flight Journal,” available online from the NASA History Division at http://www.history.nasa.gov/ap08fj.

“The point of such a picture . . .”
:
Carl Sagan, “A Pale, Blue Dot,”
Parade Magazine,
September 9, 1990, page 52.

“a pale blue dot .
  .  .”:
Ibid.

“It has been said that astronomy is . . .”
:
Carl Sagan,
Pale Blue Dot: A Vision of the Human Future in Space
(New York: Random House, 1994), pages 8–9.

selfies by subsequent planetary exploration missions
:
The Planetary Society, the world’s largest nonprofit public space-advocacy organization, hosts a delightful online collection of photographs of the Earth from space at planetary.org/explore/space-topics/earth/pics-of-earth-by-planetary-spacecraft.html.

Cassini
orbiter was passing through Saturn’s shadow
:
Ibid.

“After much work, the mosaic . . .”
:
Details and photos from the
Cassini
mission’s “The Day the Earth Smiled” photo event can be found online at photojournal.jpl.nasa.gov/catalog/PIA17171 and on
Cassini
imaging team leader Carolyn Porco’s Facebook page at facebook.com/carolynporco.

inspirational appeal as the
Pale Blue Dot
:
For lots of stories and beautiful examples of some of the most spectacular photos from the
Spirit
and
Opportunity
rover missions, see my book
Postcards from Mars
(New York: Dutton, 2006).