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Mars (last updated February 8, 2004) (back to top) Assuming no probelms, the two land rovers that NASA landed on the surface of Mars in January 2004 will spend three months each exploring their respective touchdown areas for signs that the environment once had water or once could have supported life. The Spirit rover landed on January 3 in Mars' Gusev Crater, and the Opportunity rover landed on Jan. 25 in the Meridiani Planum, on the opposite of the planet from Spirit. These rovers are part of NASA's ongoing efforts to locate areas on Mars that may once have contained water and thus would be likely areas to find evidence of past life. They also mark NASA's second and third rovers on another planet, following the Sojourner land rover that spent three months on the surface of Mars beginning in July 1997. Looking forward, NASA plans to send two more exploration rovers to Mars in June 2003 to conduct tests on two locations that might have once had water. As of October 2002, NASA's long-term plans included another reconnaissance satellite in 2005, a long-range mobile science lab in 2009, and the first-ever mission that would return samples to Earth in 2014 or later.  Genome sequencing (last updated February 9, 2002) A long-running project to sequence the entire human genome -- the massive string of DNA that controls the biological processes of life -- reached a milestone in June 2000, when public and private scientists announced the completion of a working draft of the genome. This draft was published in February 2001, and work continues on producing a complete, higher-quality map by 2003. A genome is the complete set of an organism's DNA, as expressed through 3 billion pairs of chemical bases. DNA is arranged into 24 chromosomes, physically separate molecules ranging in size from 50 million to 250 million bases. Each chromosome contains many genes, which are the basic and functional units of heredity, and which encode instructions on how to make the proteins that perform most life functions and make up most cellular structures. The working draft announced in June 2000 and published in February 2001 includes shotgun sequence data from mapped clones, with some gaps and ambiguities unresolved. Still, even this draft has led to some new discoveries as to human genetics. The human genome contains about 3.1 billion chemical bases, but less than two percent of the genome codes for proteins, and about half of the genome is so-called junk DNA, or repeated sequences that do not code for proteins and thus have no apparent direct function. The number of genes is about 30,000, which is much lower than previous estimates three to five times as high. And humans share almost the entire genome, with only 800 letter bases different out of every million, less than 1 percent. Beyond expanding scientific understanding, genome mapping is believed to have great potential in a variety of ways. Proponents believe that genome mapping can lead to advances in gene therapy and applied biotechnology, though there are massive hurdles before one can understand how genes cause diseases and how one can resolve them. On a smaller scale, DNA identification -- which uses junk DNA sequences that are virtually unique for an individual -- has already led to advances in forensics, identification, and anthropology. DNA has also led to privacy concerns and to some state laws prohibiting disclosure of one's DNA sequence and prohibiting discrimination in employment and insurance contexts based on one's DNA, though there is no such federal law yet. Plans to sequence the entire human genome began in the 1980s, with the first federal funding by the Department of Energy and the National Institutes of Health in FY 1988. Together, the DOE and NIH projects comprise what is popularly known as the Human Genome Project. The NIH's program was initially headed by James Watson, who shared a Nobel prize for discovering the double helical structure of DNA in 1953, and then by Francis Collins of the University of Michigan; the DOE's program was headed by Ari Patrinos. The project grew in size and funding, starting with about $30 million in funding in FY 1988, and growing to about $394.8 in FY 2001, for a total of about $2.9 billion over its 12-year history thus far. The project was controversial from the beginning, with many scientists criticizing the project as "big science" that would take away from other research. In the late 1990s, the public project also faced competition from a private effort that used a technique called shotgun sequencing, which gave good results for most DNA but left some junk DNA unsequenced. In May 1998, Craig Venter, formerly with the NIH, announced plans with the Perkin-Elmer Corporation to create a new company, Celera, that would sequence the entire human genome in just three years, by 2001, and for only $300 million. A few months later, in September 1998, the public project announced plans to produce a "rough draft" in 2001 and to complete the entire genome in 2003, two years ahead of schedule. The two projects finally brokered a truce in which they would declare completion and announce their drafts at the same time. In a White House ceremony on June 26, 2000, Collins, Patrinos and Venter together announced the completion of a working draft DNA sequence of the human genome, and then published the draft simultaneously, though in different journals, in February 2001. The Human Genome Project continues work on genome sequencing and plans to finish a complete, high-quality sequence by the end of 2003 and then make the sequence available for free. As of December 2001, about 63 percent of the high-quality sequence had been completed, though only two of the 24 chromosomes were fully done. Sources: The Department of Energy maintains a detailed website on the overall Human Genome Project here. The National Institute of Health runs its component of the Human Genome Project through the National Center for Biotechnology Information, and a website tracking the progress towards completion of the high-quality draft is on-line here. Celera Genomics is on-line here. Robert Cook-Deegan, The Gene Wars: Science, politics, and the human genome (W.W. Norton & Co., 1994). Cloning and Stem Cells (last updated January 11, 2003) (back to top) The debate over cloning has moved from science-fiction stories to the front pages, first with the creation of a cloned sheep in 1996 (publicly announced in 1997), and again in November 2001 with the announcement that a Massachusetts company had cloned human embryos for therapeutic purposes, though such embryos did not survive long. These efforts represent very different kinds of cloning -- the first done with reproductive intent, the second with therapeutic intent -- and science still appears to be far away from actually producing a living human being cloned from another. In late December 2002, however, Clonaid, a company founded in 1997 by the leader of a religious organization that believes humans were cloned by an alien race, announced in December 2002 that the first human clone baby had been born. Clonaid's announcement, which has not been independently verified, has sparked another round of calls for a ban on human reproductive cloning within the United States. Both the Clinton and Bush administrations have recommended such bans since the late 1990s, although President George W. Bush has called for a ban on cloning for any purpose, which would include non-reproductive cloning efforts. In any event, even a broad ban might have limited effect; Clonaid itself says that it moved out of the United States in order to avoid governmental interference. All known successful cloning attempts have started the same way, with a technique called nuclear transplantation, or somatic cell nuclear transfer. This involves taking an egg and replacing its nucleus with one taken from an adult subject. This reconstructed cell is then stimulated to begin dividing and will produce a pre-implantation embryo, what is called a blastocyst. What happens next depends on the ultimate purpose behind the cloning. In reproductive cloning, the blastocyst is then implanted into a uterus so that it can form a fetus, which then can develop into a genetically identical match to the adult subject that provided the implanted nucleus; this is how Dolly was created. In therapeutic cloning, however, cells from the blastocyst are isolated and then used to make a stem cell line for further research and clinical applications; the blastocyst is not implanted into a uterus and does not ever become a fetus. Scientists have managed to use nuclear transplantation successfully with some species -- such as sheep, mice, pigs, goats and cattle -- but not with others, such as monkeys, dogs, and horses. Even when successful, however, nuclear transplantation is an inefficient process; many eggs are required to yield a few successes, many clones die during gestation or have abnormalities, and the mother carrying the implanted embryo bears many risks. Due to these risks -- as well as the risk of ovarian hyperstimulation syndrome in any human women who donate eggs for this or any other process -- scientists and politicians generally have supported a ban on human reproductive cloning at the present time. President Clinton's National Bioethics Advisory Commission recommended a temporary ban in June 1997 after Dolly's creation was revealed to the world, and a panel by the National Academies made a similar recommendation in January 2002. President George W. Bush has called for a permanent ban on cloning for any purpose, and appointed a commission to study the issue as well; that commission had its first meeting in January 2002. However, the reach of such a ban is controversial. While scientists and politicians agree on a ban on human reproductive cloning, many disagree on whether there should be such a ban on therapeutic cloning. This is where embryonic stem cells come into the debate. Embryonic stem cells have been controversial in recent years, in recent years especially because of their connection with therapeutic cloning. Stem cells are unspecialized cells that can self-renew indefinitely and that can develop into more mature cells with specialized functions, and embryonic stem (ES) cells, which are derived from an early-stage embryo, are especially promising because they potentially could be developed into a wide variety of tissues for transplantation into patients with diseases such as Alzheimer's. What first made ES cell lines so controversial is that they have generally been derived from sources such as aborted fetuses and embryos resulting from in-vitro fertilization, thus raising questions as to whether such embryos are alive and should be used for such research. Whether the federal government should fund the development of such cells grew into a major policy question in recent years, culminating with President George W. Bush's decision on August 9, 2001 to allow federal funding for research on then-existing stem cell lines as long as the lines were derived from embryos that were already destroyed and that had not been created specifically for research. "We should allow federal funds to be used for research on these existing stem cell lines, where the life and death decision has already been made," Bush said in his first major non-augural public speech as president. "Leading scientists tell me research on these 60 lines has great promise that could lead to breakthrough therapies and cures. This allows us to explore the promise and potential of stem cell research without crossing a fundamental moral line, by providing taxpayer funding that would sanction or encourage further destruction of human embryos that have at least the potential for life." As of February 2002, the Human Embryonic Stem Cell Registry, which is run by the National Institutes of Health, counted 72 stem cell lines at 11 laboratories (five in the United States, including a Wisconsin-based group that had patented several lines, two in Sweden and India each, and one in Australia and Israel each) as meeting the criteria that Bush established. Still, some scientists have criticized Bush's order for limiting the development of more and better-quality stem cell lines. In any case, Bush's order did not go so far as to ban private research that did not meet his criteria; such research simply has to go on without federal funding. The debates over stem cells and cloning became intertwined in November 2001, when a Massachusetts-based company, Advanced Cell Technology, announced that it had attempted to create ES cells through nuclear transplantation. The hope here was that scientists could use cloned human embryos to create embryonic stem cells that could develop into tissues that would perfectly match the person who was cloned, thus ensuring that the person's body would accept such tissue transplants and not reject them as foreign. Advanced Cell Technology reported that it had successfully transplanted a human nucleus into a human egg, but that the most successful resulting embryo still did not grow enough to produce a blastocyst that could yield stem cells, stopping growth after dividing into only six cells. Advanced Cell Technology also tried creating cloned embryos through another method called parthenogenesis, by which eggs are stimulated to divide into early embryos. Of the 22 eggs chemically induced via parthogenesis, all died, and none developed the inner cell mass that yields stem cells. Nevertheless, even these limited results set off a new wave of controversy over cloning. "The use of embryos to clone is wrong. We should not as a society grow life to destroy it," Bush said in a ceremony soon after the announcement, and he quickly established a bioethics commission headed by University of Chicago professor Leo Kass to make recommendations on the subject. That commission met for the first time in January 2002. Bush has called for a ban on all cloning. The House of Representatives passed such a bill in July 2001, which would ban cloning of any kind and subject violators to criminal penalties such as prison and fines. Senator Sam Brownback (R-Kansas) has introduced a measure that would also ban cloning for any purpose, though the Senate has not yet considered it. However, many scientists have opposed such a total ban, urging legislators to distinguish between reproductive and therapeutic cloning. The National Academies' National Research Council and Institute of Medicine, for example, recommended public funding of stem cell production in September 2001 and then recommended in January 2002 a ban on human reproductive cloning for at least five years. Sources: President Clinton's National Bioethics Advisory Commission did a report on cloning in September 1997, available on-line here, and a report on stem cells in September 1999, available here. The National Academies did a report on reproductive cloning in January 2002 and a report on stem cells in September 2001; both are available via the Academies' website, on-line here. President Bush's August 9, 2001 speech announcing his decision on stem cells is on-line here. The National Institutes of Health maintains information on stem cells and on the stem cell registry here. Advanced Cell Technology is on-line here, and a January 2002 Scientific American article describing their research is on-line here. Gina Kolata with Andrew Pollack, A Breakthrough on Cloning? Perhaps, or Perhaps not Yet, New York Times, November 27, 2001. Sheryl Gay Stolberg, Bush denounces cloning and calls for ban, New York Times, November 27, 2001. Clonaid is on-line here. The "Gay Gene" Debate (last updated March 22, 2005) (back to top) Scientists, doctors and psychologists once saw homosexuality as a disease, but now some scientists are trying to prove that sexual orientation has biological explanations such as genetics, brain differences, or neurochemistry. Such efforts have so far not proven conclusive, though the debate as to whether sexual orientation is a choice or is biologically determined continues and became an issue in the second presidential debate (on-line here), when Sen. John Kerry said that he believed sexual orientation was not a choice. Biological explanations for homosexuality could impact society's acceptance of homosexuality by showing that discrimination against homosexuals is based on factors beyond such persons' control. But some also wonder if biological advances would then allow the possibility of eradicating homosexuality in the future. Some studies that have suggested evidence of biological explanations are listed below:
The Theory of Everything, aka Grand Unification Theory (last updated August 2001) The Grand Unification Theory, if ever completed, would probably be one of the biggest accomplishments of modern science. For decades, physicists have been searching for a theory that would explain the four known forces - the electromagnetic, gravitational, strong and weak forces (strong forces hold atomic nuclei together, and weak forces are responsible for slow nuclear processes such as beta decay) - under one set of general laws. Currently, the workings of the physical universe can only be explained through the laws of these forces separately, and physicists believe that there must be some "unified" way to bring these systems together into one comprehensive theory. Einstein tried for years but could not do it. He tried to unite relativity and classical physics, but was unwilling to accept quantum mechanics. Physicists Steven Weinberg and Abdus Salam united the weak force and the electromagnetic force in the 1960s. Physicists then incorporated strong interactions into this theory, which has become known as the Standard Model of particle physics, which explains how elementary particles and forces work. The next step is to unite the Standard Model with the theory of general relativity, which governs gravity and the nature of space-time geometry. One way scientists have been trying to complete the theory is through particle accelerators that are capable of discovering new elementary particles. The top quark, discovered in the 1990s, is the heaviest known particle of the Standard Model. Scientists have also been developing new models for thinking about the universe. One idea is that particles actually are strings at low energy levels. Would the discovery of the Grand Unification Theory change much about everyday life? Probably not. But it would open new doors of scientific discovery and thinking, just as the discovery of DNA opened new possibilities that, decades later, are reshaping our understanding of our basic biological existence. Sources: David Lindley, The End of Physics: the Myth of a Unified Theory (1993). Steven Weinberg, Dreams of a Final Theory (1994). Steven Weinberg, A Unified Physics by 2050?, Scientific American, available here. For a fictional look, see Greg Egan, Distress (1995). High-energy physics, the Higgs boson, and particle accelerators (last updated March 10, 2002) By accelerating subatomic particles to extremely high energies and then colliding them, high-energy physicists can find evidence that would hopefully solve major problems in theoretical physics. But to run these experiments, they need particle accelerators, massive equipment that can cost billions of dollars and involve miles of underground tunnels. The United States began construction of what would have been the world's most powerful particle accelerator, the Superconducting Super Collider, but that project was killed during budget cuts in 1993. Since then, high-energy physicists have looked to Europe, where construction of a powerful collider (still weaker than the SCSC would have been) was approved in 1994 and is expected to be finished by 2006, and are beginning to propose that the United States try again and build a complementary accelerator. Particle physics aims, generally, to explain how the four fundamental forces of the universe (electromagnetic reactions, strong interactions, weak nuclear force, and gravity) interact with each other. Over the past few decades, physicists have developed a Standard Model that explains the interaction of all the forces but gravity, and they have proven this paradigm in most regards. (A theory that would explain the interaction of all four forces is generally called a grand unification theory, or a theory of everything; for more, go here) One big hole in the Standard Model is that it does not yet fully explain why particles have mass, which would explain how the symmetry relating the weak and electromagnetic interactions was broken as the temperature of the universe cooled after the big bang. In the 1960s, British physicist Peter Higgs proposed a solution, theorizing that space is filled with a field through which all other subatomic parties must pass and, in doing so, experience a drag that results in mass. In order to prove this theory, physicists must discover the Higgs boson, a particle that would be associated with the Higgs field, if it exists. Discovering new sub-atomic particles requires taking protons and electrons apart, a process that requires massive amounts of energy. Physicists have thus used particle accelerators and colliders already in existence, such as the Tevatron at the Fermi National Laboratory in suburban Chicago, to discover particles like the quark. In order to move particle physics forward, high-energy physicists in the United States proposed the Superconducting Super Collider in the 1980s. If built, the SCSC would have accelerated protons to energies of 20 trillion volts, which is expected to be enough to settle the question of why the symmetry relating the weak and electromagnetic interactions was broken, either by finding the Higgs boson or by finding new extra-strong forces. The SCSC took its first big step towards reality in 1988, when the Department of Energy selected the Dallas-Fort Worth region of Texas as the site for the Superconducting Super Collider (specifically, the town of Waxahachie in Ellis County). Texas was one of seven finalist states lobbying for the project, and it even offered $1 billion in bonds to help fund the project. Illinois, which proposed building around the already-existing Fermi National Laboratory outside Chicago, was also considered a front-runner but lacked local support. The project ultimately brought much federal funding and 7,000 jobs to Texas with the promise of even more for years to come, and it thus won strong allies in Congress from Texas and Louisiana, where the magnets used in the SCSC were built. President George Bush was a strong supporter, and Bill Clinton promised to keep the project alive during his 1992 presidential campaign. Nevertheless, the SCSC became a prime target for budget cuts in the early 1990s, especially as reports of cost overruns and mismanagement emerged, and as hopes of funding from other countries failed to become realized. Beginning in the summer of 1992, the House of Representatives undertook a concerted campaign to stop the SCSC. The House first voted to stop funding in the summer of 1992 and did so again in the summer of 1993, but these efforts were rejected by the Senate. The House's third vote on October 19, 1993 proved to be the fatal blow to the project, and it was officially killed on October 21, 1993. By this time, $2 billion had been spent on the SCSC and 14 miles of tunnels excavated, though estimated costs for the entire project had risen from $4.4 billion in 1988 to $13 billion. Department of Energy officials estimated that the project was 20 percent complete. Since 1993, high-energy physicists in the United States have continued using accelerators already in existence and have looked increasingly to CERN (the European Laboratory for Particle Physics). In 1994, the member nations of the CERN voted to build the Large Hadron Collider. The LHC is expected to accelerate protons to energies of 14 TeV and become the most powerful accelerator in the world, but will still be far short of the 20 TeV energy that the SCSC would have achieved. The United States is contributing about $500 million to the $4 billion project. In recent years, high-energy physicists have begun discussing proposals for building a new, extremely powerful particle accelerator to complement the LHC. The proposed accelerator would accelerate particles along a linear track (about 20 miles long) rather than a circular one, it would use electrons rather than protons, and it would attain lower energies but more precise measurements than the LHC. Many high-energy physicists in the United States have proposed building it in the United States, possibly near or at the Fermilab facility. In January 2002, an advisory panel to the Department of Energy and the National Science Foundation recommended such a proposal. Current estimates are that it would cost $6 billion. There are several laboratories in the United States currently conducting accelerator-based experiments. Until the LHC is completed, the Fermilab's Tevatron Collider remains the world's most powerful accelerator; like the LHC, it accelerates protons along a circular track. Stanford University has the Stanford Linear Accelerator Center, which accelerates electrons along a linear track. There are other accelerators at Brookhaven National Laboratory and Cornell University. Sources: Steven Weinberg, Dreams of a Final Theory (Vintage Books edition, January 1994). The Department of Energy and National Science Foundation High-Energy Physics Advisory Panel's January 2002 report on long-range planning can be found on-line here. The Fermi National Laboratory is on-line here. Explanations for the Higgs boson are available online here. Gary Taubes, The Supercollider: How big science lost favor and fell, New York Times, October 26, 1993. James Glanz, Particle physicists plan the next big thing, New York Times, July 10, 2001. The Future of U.S. High Energy Physics, a May 23-24, 1994 hearing of the House of Representatives' Subcommittee on Science. Termination of the Superconducting Super Collider Project, a March 15, 1994 hearing of the House of Representatives' Subcommittee on Science. |
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