Notes for:

^*     Dr. Rodrigue is Chair and Professor of Geography at California State University, Long Beach, CA. She earned her Ph.D. from the Graduate School of Geography at Clark University. E-mail: rodrigue@csulb.edu.

¹     An elected decision-maker is faced with a set of career risks in deciding what to do in response to public pressure about a given issue, including risk management policy decisions. These risks can be understood in terms of Type I and Type II errors in statistics. Facing constituent pressure concerning a given technological risk, does an elected decision-maker decide the null hypothesis is true and the constituent communications are representative of the feelings of most constituents and act accordingly? If the communications are in fact not representative, s/he may alienate the bulk of constituents by so doing (Type II error), not to mention any politically influential interests at loggerheads with the bulk of constituent communications. If the communications are representative of the will of the majority and an elected official fails to recognize this, s/he faces a Type I error in choosing to ignore the communications. This argument is adapted from Larry C.F. Heiman, Acceptable Risks: Politics, Policy, and Risky Technologies (The University of Michigan Press, 1997).

²     See e.g., Thomas A. Birkland,. Natural Disasters as Focusing Events: Policy Communities and Political Response, 14(2) International Journal of Mass Emergencies and Disasters, p. 221-243 (1996); Ute J. Dymon & Francis P. Boscoe. Newspaper Reporting in Wake of the 1995 Spring Floods in Northern California. Natural Hazards Center, University of Colorado, Boulder, 81 Quick Response Report (1996) (available at <http://www.colorado.EDU/hazards/qr/qr81.html>); D. Elliott, Tales from the Darkside: Ethical Implications of Disaster Coverage. In Bad Tidings: Communication and Catastrophe (Lynne Masel Walters, Lee Wilkins, & Tim Walters eds., Lawrence Erlbaum Assoc., 1989); Roger E. Kasperson, Ortwin Renn, Paul Slovic, Halina S. Brown, Jacque Emel, Robert Goble, Jeanne X. Kasperson and Samuel Ratik, The Social Amplification of Risk: A Conceptual Framework 8 Risk Analysis (1988), p. 177-187. Karen Lowrie, Michael Greenberg, & Lynn Waishwell, Hazards, Risk, and the Press: A Comparative Analysis of Newspaper Coverage of Nuclear and Chemical Weapons Sites, 11 (1) Risk: Health, Safety & Environment (2000); Allan Mazur, Looking Back: Unneeded X-rays, 11 Risk: Health, Safety & Environment 1 (2000); Allan Mazur, A Hazardous Inquiry: The Rashomon Effect at Love Canal (Harvard Univ. Press, 1998); Allan Mazur, Technical Risk in the Mass Media, 5 Risk: Health, Safety & Environment 3 (1994); Conrad Smith, Media and Apocalypse: News Coverage of the Yellowstone Forest Fires, Exxon Valdez Oil Spill, and Loma Prieta Earthquake (Greenwood Press, 1992); Robert A. Stallings, Hindsight, Organizational Routines and Media Risk Coverage, 5 Risk: Health, Safety & Environment 3 (1994).

³     See e.g., Mike Davis, The Case for Letting Malibu Burn, Ch. 3 of his Ecology of Fear: Los Angeles and the Imagination of Disaster (Metropolitan Books, 1998); Marla Perez-Lugo, The Mass Media, Political Fragmentation, and Environmental Injustice In Puerto Rico: A Case Study Of The Floods In Barrio Tortugo, 113 Quick Response Report (1999) (available at <http://www.colorado.EDU/hazards/qr/qr113.html>); Christine M. Rodrigue, Eugenie Rovai, & Susan E. Place, Construction of the "Northridge" Earthquake in Los Angeles' English and Spanish Print Media: Damage, Attention, and Skewed Recovery, paper presented to the second Southern California Environment and History Conference (1997) (available at <https://home.csulb.edu/~rodrigue/scehc97.html>); Eugenie L. Rovai, The Social Geography of Disaster Recovery: Differential Response to the North Coast Earthquakes, 56 Yearbook of the Association of Pacific Coast Geographers (1994), p. 49-74; Eleanor Singer & Phyllis M. Endreny, Reporting on Risk: How the Mass Media Portray Accidents, Diseases, Disasters and Other Hazards, 5 Risk: Health, Safety & Environment 3 (1994).

⁴     See NASA, Passage to a Ringed World: The Cassini-Huygens Mission to Saturn and Titan (Spilker, Linda J., ed., 1997) (available at <http://www.jpl.nasa.gov/cassini/english/teachers/pub/passage/>).

⁵     See NASA, Final Environmental Impact Statement for the Cassini Mission (Solar Exploration Division, Office of Space Science, 1995); NASA, , Final Supplemental Environmental Impact Statement for the Cassini Mission (Office of Space Science, NASA, 1997) (available at <http://www.jpl.nasa.gov/cassini/english/msnsafe/>).

⁶     Norman Holden, Table of the Isotopes (Revised 1998), CRC Handbook of Chemistry and Physics (David R. Lides ed., 2000).

⁷     Testimony provided by John Gofman in Comm. vs. Sam Lovejoy (excerpted at <http://www.ecn.cz/temelin/Lovejoy.htm#Gofman>).

⁸     This Ralph Nader quotation is frequently encountered and often unattributed. It was made in a debate between Nader and Ralph Lapp in 1975, in which Nader stated that one pound of plutonium could kill every human being on Earth. The debate is discussed in Theodore Rockwell, Discussions of Nuclear Power Should Be Based in Reality, 12 (6) The Scientist (March 16, 1998) and in Bernard L. Cohen, The Myth of Plutonium Toxicity (Karl O. Ott & Bernard I. Spinard, eds. Plenum Press, 1985).

⁹     See NASA, supra, at 1, 3-4, 2-74; NASA (1997), supra, at Sec. 2.

¹⁰     See e.g. Daniel Chong, Nukes in Space: The Final Frontier? NASA To Launch Nuclear-Powered Space Probe, Awareness Magazine (Sept./Oct. 1997) (available at <http://www.awarenessmag.com/sepoct7.html/so7_nuke.html>; Karl Grossman, Risking the World: Nuclear Proliferation in Space, Covert Action Quarterly (Summer 1996) (available at <http://caq.com/fallingnukes/>); Russell D. Hoffman, Cassini: An In- Depth Look (Jan. 30, 1997) (available at <http://www.animatedsoftware.com/cassini/cassiplu.htm>); and Michio Kaku, A Scientific Critique of the Accident Risks from the Cassini Space Mission, The Real News Page (Aug. 1997) (available at <http://www.americanreview.net/kaku1.htm>).

¹¹     See J. C. Nenot & J. W. Stather, The Toxicity of Plutonium, Americium, and Curium (Pergamon Press 1979).

¹²     All estimates for any of the launch phases for expectation and maximum scenarios were below one health effect, i.e., surplus cancer death. See NASA (1995), supra at 4.57-4.58. For an inadvertant entry during the Earth swingby, depending on the angle of re-entry, the estimate ranged from 1,910 to 3,480 excess deaths developing over five decades, a level that would not be statistically observable among the 1 billion or so deaths normally expected in that time frame. Id. at 4.59. This estimate was calculated without the controversial de minimis assumption of an allegedly harmless dose of 0.001 rem. These estimates were revised downward in the Final Supplemental EIS of 1997 after application of new probabilistic safety analyses and more detailed descriptions of accident and environment scenarios. For pre-launch and launch accidents, expected surplus deaths again remained below one for all phases, and worst case scenarios resulted in less than 1 % probabilities of from 0.55 to 1.50 surplus deaths being exceeded, depending on the time of failure. See NASA (1997) supra n. 5, at 2.20-2.22. For inadvertant entry failures, there was a substantial drop in expected excess deaths, to 120, with a 1 % probability of 450 surplus deaths being exceeded. Id. at 2.22-2.23.

¹³     Signaled by the publication of Karl Grossman, Apollo Outtakes, The Nation (Sept. 11, 1995) (available at: <http://www.animatedsoftware.com/cassini/kg9509na.htm>).

¹⁴     Kaku, supra n. 10, at top of document.

¹⁵     Karl Grossman, The Risk of Cassini Probe Plutonium, Christian Science Monitor (October 10, 1997) (available at <http://www.csmonitor.com/durable/1997/10/10/opin/opin.1.html>).

¹⁶     See NoFlyBy <http://www.nonviolence.org/noflyby/> (accessed November 7, 2001).

¹⁷     See Grossman, supra n. 15.

¹⁸     J. Turner, Nuking the Final Frontier, 5 (4) Shift (1997).

¹⁹     See e.g., Helen Caldicott, Nukes in Space Are a Serious Threat to Us All, Sydney Morning Herald (August 18, 1999) (available at <http://www.gn.apc.org/cndyorks/yspace/articles/caldicott.htm>); Karl Grossman and Jonathan Mark, The FORCE behind Cassini, press release (July 21, 1999) (available at <http://www.nonviolence.org/noflyby/alerts/18n.htm>); Karl Grossman, Space Use and Ethics, speech at Space Use and Ethics Conference, Darmstadt, Germany (March 4, 1999) (available at <http://www.nonviolence.org/noflyby/karl/ethics.htm>); Al Decker, Hey NASA: Send It Up Uranus! -- Opposition to Cassini Heats Up, EarthFirst! Journal (available at < http://www.enviroweb.org/ef/old/Lughnasadh97/Cassini.html>).

²⁰     See e.g., Stop Cassini Newsletter index (available at <http://www.animatedsoftware.com/cassini/nltrs/index.htm>). This claim is at least partly based on statements by the American military about its mandate to assure American military control of space. See e.g., United States Space Command, Long Range Plan: Implementing USSPACECOM Vision for 2020 (available at <http://www.peterson.af.mil/usspace/LRP/cover.htm>).

²¹     See e.g., NoFlyBy site, supra n. 16.

²²     See e.g., Dave Weldon, NASA's Cassini Mission Is Safe, Space News (September 22-28, 1997) (available at <http://www.reston.com/nasa/congress/09.05.97.weldon.cassini.html>).

²³     See United States Government Accounting Office, Space Exploration -- Power Sources for Deep Space Problems, GAO/NSIAD-98-102 (1998)(available at <http://www.gao.gov/archive/1998/ns98102.pdf>).

²⁴     See Grossman (1997), supra n. 15; City of Santa Cruz, City Council Minutes of 9/9/97, (available at <http://www.ci.santa-cruz.ca.us/cc/archives/97/9-9m.html>); and Marin County Resolution No. 97-26, (available at <http://www.co.marin.ca.us/bos/bosagmn/m970325.txt>).

²⁵     See e.g., Regina Hagen, Nuclear Powered Space Missions - Past and Future (Aug. 11, 1998) (available at <http://www.globenet.free-online.co.uk/ianus/npsmindex.htm>). Controversy over RTGs has encouraged innovation within NASA concerning alternative power sources for deep space missions, including efforts to develop solar concentrators and more efficient thermoelectric conversion devices for RTGs to minimize the amount of Pu-238 required. See Glenn Research Center at Lewis Field and NASA, Deep Space Solar Stirling (Jan. 4, 2000) (available at <http://www.lerc.nasa.gov/WWW/tmsb/dynamicpower/doc/stirling_deepsolar.html&ht;). The Discovery Program of smaller missions explicitly forbids designs dependent on RTGs (though the smaller RHUs are permissible). See NASA, DRAFT for Community Comment, Announcement of Opportunity, Discovery Program (Jan. 9, 1998) (available at: <http://spacescience.nasa.gov/aodraft/discovery/discdrft.txt>).

²⁶     For examples of print media pieces on the controversy, see William J. Broad, Powered by Plutonium, Saturn Mission Provokes Warnings of Danger, N.Y. Times (Sept. 8, 1997) (available at <http://www.nonviolence.org/noflyby/ref/nyt98.htm>); Karl Grossman, Nuclear Menace in Outer Space, Baltimore Sun (Dec. 8, 1996) (available at <http://www.nonviolence.org/noflyby/ref/kg9612ba.htm>); Robyn Suriano and Tony Boylan, Demonstration ends with 27 arrested, Florida Today (Oct. 5, 1997) (available at <http://www.nonviolence.org/noflyby/ref/flt105.htm>:. For examples of broadcast media pieces, see Cassini Segment, 60 Minutes (CBS News Col, Oct. 5, 1997) (transcript available at <http://www.prop1.org/2000/cassini/971005fl.htm>); Karl Grossman, Nukes in Space: The Nuclearization and Weaponization of the Heavens (1995) and Nukes in Space II: Unacceptable Risks (1998), EnviroVideo, Box 311, Ft. Tilden NY 11695; Interviewed by Art Bell Coast to Coast Radio Show with Michio Kaku (Sept. 24, 1997).

²⁷     For examples of web pages, see <http://www.nonviolence.org/noflyby/>, <http://www.animatedsoftware.com/cassini/>, <http://www.rain.org/~openmind/cassini.htm>, <http://www.jpl.nasa.gov/cassini/>, and <http://www.jpl.nasa.gov/cassini/english/msnsafe/>.

²⁸     For statements expressing reservations about raw public input, see e.g., Norman Augustine, What We Don't Know Does Hurt Us: How Scientific Illiteracy Hobbles Society, 279 Science 5357 (1998); Baruch Fischhoff, Acceptable Risk: A Conceptual Proposal, 5 Risk: Health, Safety & Environment 1 (1994); and Sharon M. Friedman, The Media, Risk Assessment and Numbers: They Don't Add Up, 5 Risk: Health, Safety & Environment 3 (1994). For statements that public input is seen as limited in value by risk assessors and managers, see e.g., Branden Johnson, Advancing Understanding of Knowledge's Role in Lay Risk Perception, 4 Risk: Health, Safety & Environment 3 (1993); Frances M. Lynn, Public Participation in Risk Management Decisions: The Right to Define, the Right to Know, and the Right to Act, 1 Risk: Health, Safety & Environment (1990); Thomas O. McGarity, Public Participation in Risk Regulation, 1 Risk: Health, Safety & Environment 2 (1990); Kristin S. Shrader-Frechette, Perceived Risks versus Actual Risks: Managing Hazards through Negotiation 1 Risk: Health, Safety & Environment 4 (1990); Paul Slovic, Beyond Numbers: A Broader Perspective on Risk Perception and Risk Communication. In Acceptable Evidence: Science and Values in Risk Management (Deborah G. Mayo & Rachelle D. Hollander eds., Oxford University Press, 1991).

²⁹     See e.g., Vincent T. Covello, Peter M. Sandman, & Paul Slovic, Guidelines for Communicating Information about Chemical Risks Effectively and Responsibly, in Mayo & Hollander, supra n. 28; Johnson, supra n. 28; Howard Margolis, Dealing with Risk: Why the Public and the Experts Disagree on Environmental Issues (The University of Chicago Press, 1996); Slovic, supra n. 28; Paul Slovic, Baruch Fischhoff, & Sarah Lichtenstein, Rating the Risks: The Structure of Expert and Lay Opinions, in Risk in the Technological Society (Christoph Hohenemser & Jeanne X. Kasperson eds., Westview Press, 1982).

³⁰     See Mary Douglas & Aaron Wildavsky, Risk and Culture: An Essay on the Selection of Technical and Environmental Dangers (Univ. of Cal. Press, 1982).

³¹     See e.g., Kristin S. Shrader-Frechette, Evaluating the Expertise of Experts, 6 Risk: Health, Safety & Environment 2 (1995); Margolis, supra n. 29; Andrew F. Fritsche, The Moral Dilemma in the Social Management of Risks, 7 Risk: Health, Safety & Environment 3 (1996); Slovic supra n. 28; Slovic, Fischhoff, and Lichtenstein, supra n. 29; Eeva K. Berglund, Knowing Nature, Knowing Science: An Ethnography of Local Environmental Activism (The White Horse Press, 1998); Lennnart Sjöberg, World Views, Political Attitudes, and Risk Perception, 9 Risk: Health, Safety & Environment 2 (1998).

³²     See Slovic, supra n. 28; Slovic, Fischhoff, & Lichtenstein, supra n. 29.

³³     Id.

³⁴     See e.g., Berglund, supra n. 31; Margolis, supra n. 29; Kristin S. Shrader-Frechette, First Things First: Balancing Scientific and Ethical Values in Environmental Science, 88 (2) Annals of the Association of American Geographersd (1998).

³⁵     See e.g., Slovic, supra n. 28; Vincent Covello, Risk Comparisons and Risk Communication. In Communicating Risk to the Public (Roger E. Kasperson & Pieter Jan M. Stallen, eds., Kluwer 1991).

³⁶     See e.g., Douglas & Wildavsky, supra n. 30; Berglund, supra n. 31; Fritsche, supra n. 31; Margolis, supra n. 29; Sheila Jasonoff, Acceptable Evidence in a Pluralistic Society, in Mayo & Hollander, supra n. 28; Howard Kunreuther, Paul Slovic, & Donald MacGregor, Risk Perception and Trust: Challenges for Facility Siting, 7 (2) Risk: Health, Safety & Environment (1996).

³⁷     See e.g., Denise Blanchard-Boehm, Risk Communication in Southern California: Ethnic and Gender Response to 1995 Revised, Upgraded Earthquake Probabilities, Natural Hazards Center, University of Colorado, Boulder, 94 Quick Response Report (1997) (available at <http://www.colorado.EDU/hazards/qr/qr94.html>; John-Paul Mulilis, Gender and Earthquake Preparedness, 14 (1) Australian Journal of Emergency Management (available at <http://www.ema.gov.au/5virtuallibrary/pdfs/vol14no1/mulilis.pdf>); Robert T. Bolin, Martina Jackson, & Allison Crist, Gender Inequality, Vulnerability and Disasters: Issues in Theory and Research. In Through Women's Eyes: The Gendered Terrain of Natural Disaster (Elaine Enarson and Betty Hearn Morrow, eds., Praeger, 1998).

³⁸     CataList reports nearly 180,000 lists conducted through LISTSERV software alone <http://www.lsoft.com/catalist.html>. Liszt, now Topica.com, provides access to 80,000 lists moderated through LISTSERV, ListProc, and Majordomo list management packages, over 35,000 IRC chat channels, and 30,000 UseNet news groups <http://www.liszt.com/>. PAML catalogues over 7,000 publically available mailing lists, as well <http://paml.net/>.

³⁹     Google, the search engine company, acquired the Déja.com UseNet search engine in February 2001. <http://www.deja.com/home_ps.shtml> thus now transfers to <http://groups.google.com/googlegroups/deja_announcement.html>.

⁴⁰     There were many messages about Oleg Cassini, the fashion designer; Nadia Cassini, an actress; Jean-Dominique Cassini, the seventeenth century astronomer and discoverer of Saturn, for whom the orbiter is named; amateur astronomers' postings on the Cassini Division or gap between Saturn's A and B rings; The Cassini Division, a science fiction novel by Ken MacLeod; and a number of postings by authors surnamed Cassini

⁴¹     See Gail L. Grant, Internet Users Top 92 Million in the U.S. and Canada, CommerceNet Research Note #99-26 (June 23, 1999) (available at <http://www.commerce.net/research/reports/1999/99_26_n/99_26_n.html>.

⁴²     Id.

⁴³     See Grossman, supra n. 10, 13, 15, 19, & 26; Grossman and Mark, supra n. 19; Karl Grossman, U.S. Slinging Plutonium into Space, The Cleveland Plain Dealer (May 22, 1996) (available at <http://www.animatedsoftware.com/cassini/kg9605pl.htm>).

⁴⁴     See e.g., Karl Grossman, Nuclear Space Missions Break Down Political Barriers, 28 Just Peace, Florida's Peace & Justice Newspaper (1993) (available at: <http://www.animatedsoftware.com/cassini/kg9328jp.htm>); Karl Grossman, Kiss Florida Goodbye? N.Y. Times (Oct. 17, 1989) (available at: <http://www.animatedsoftware.com/cassini/kg8910ny.htm>); Karl Grossman, We Don't Need Reactors in Space: Ignoring Safe Solar Power, We Send Plutonium-Laden Probes into Orbit, Newsday: The Long Island Newspaper (May 31, 1991) (available at <http://www.nonviolence.org/noflyby/karl/kg9105we.htm>); Karl Grossman, Plutonium Shuttle: The Space Probe's Lethal Cargo, The Nation (Jan. 23, 1988) (available at <http://www.nonviolence.org/noflyby/karl/kg8801tn.htm>).

⁴⁵     See Project Censored web page <http://www.projectcensored.org/intro.htm>

⁴⁶     See <http://www.animatedsoftware.com/cassini>.

⁴⁷     See <http://www.americanreview.net/cassini.htm>.

⁴⁸     See Bruce Gagnon, Cassini Is a Bad Seed, Rat Haus Reality (July 1997) (available at <http://www.ratical.org/radiation/cassini.html>).

⁴⁹     See <http://www.lovearth.net/> to get a sense of the Lovearth network, but their Cassini materials have been removed at this writing.

⁵⁰     See Jonathan Mark and Earl Budin, NASA Misleads the World on the Dangers of the Cassini Space Ship's Fly-by of Earth, Global Network against Weapons and Nuclear Power in Space web site <http://www.globenet.free-online.co.uk/cassini/stopcass.htm>; Grossman and Mark, supra n. 19; and the NoFlyBy web site, supra n. 16.

⁵¹     See Kaku, supra n. 10.

⁵²     See Gofman, supra n. 7; PBS Forum, Risks Vs. Returns: Is the Cassini Mission Safe? (Oct. 21, 1997) (available at <http://www.pbs.org/newshour/forum/october97/cassini4.html>).

⁵³     See Ross McCluney, Solar Solutions For Cassini, The Cassini Debate and Beyond (Jane W. Prettyman, ed.), American Review (Aug. 14, 1997) (available at <http://www.americanreview.net/cassolar.htm>).

⁵⁴     See Caldicott, supra n. 19; Helen Caldicott, Speech at NASA Ames Research Center, 125 Stop Cassini Newsletter (available at <http://www.animatedsoftware.com/cassini/nltrs/nltr0125.htm>).

⁵⁵     See Mark and Budin, supra n. 50; Earl Budin, Letters to the UN (April 2, 1999) (available at <http://www.nonviolence.org/noflyby/ref/budin2.htm>); Budin (March 12, 1999) (available at <http://www.nonviolence.org/noflyby/ref/budin3.htm >).

⁵⁶     See Russell D. Hoffman, Dr. Sternglass and Me (April 8, 1997) (available at <http://www.animatedsoftware.com/cassini/ster9704.htm>).

⁵⁷     See Horst A. Poehler, Cassini Cancers ("The Plutonium Story"), Stop Cassini (August 1997) (available at <http://www.animatedsoftware.com/cassini/hp9708ps.htm>:).

⁵⁸     See Alan Kohn, Speech at Cape Canaveral Air Force Station Main Gates (July 26, 1997) (available at <http://www.prop1.org/2000/cassini/9707kohn.htm>). Mr. Kohn was the Emergency Preparedness Operations Officer at Cape Canaveral during the Galileo and Ulysses launches.

⁵⁹     Ron Baalke is a webmaster for JPL missions and publicizes mission events on UseNet newsgroups.

⁶⁰     Mary Beth Murrill is the News Chief for JPL and handles publicity concerning space nuclear power and institutional environmental issues.

⁶¹     See e.g., Robert Anton Wilson, The New Inquisition: Irrational Rationalism and the Citadel of Science (Falcon Press, 1987).

⁶²     The main organizers of the anti-Cassini movement were conflicted over this Nostradamus angle that had descended on them. Russell Hoffman was appalled at this development, fearing for the credibility of the movement. He wrote "Right now, I think the BIGGEST problem facing the movement is that NASA/JPL is trying to make it look like there is no scientific objection to Cassini -- instead, pretending that there is only Nostradamus-related confusion." See Stop Cassini Newsltr 93 (9 Feb. 1999) (available at <http://www.animatedsoftware.com/cassini/nltrs/nltr0093.htm>). The NoFlyBy people decided to encourage the Nostradamus fans in an "enemy of my enemy is my friend" strategy, expressed in their response to "an appeal for information on Nostradamus or other possible pathways to lead to the interest of the media, even including the tabloids. It is not the time to be fussy." See NoFlyby Newsletter 9 (Dec. 23, 1998) (available at <http://www.nonviolence.org/noflyby/alerts/9.htm>).

⁶³     See e.g., <http://www.jpl.nasa.gov/cassini/english/msnsafe/introlinks.html>.

⁶⁴     See e.g., <http://www.jpl.nasa.gov/cassini/english/msnsafe/>, although this was updated and substantially improved in May 2000.

⁶⁵     Letter from Thomas Jefferson to William C. Jarvis (Sept. 28, 1821), in Writings of Thomas Jefferson in Twelve Volumes vol 10 (G.P. Putnam's Sons 1904) (available at <http://memory.loc.gov/mss/mtj/jtj1/052/0200/0276.jpg>).

    Note: All links given here were verified as working as of 11/07/01. As time goes on, however, their accuracy will degrade as web authors change their sites or close them.