Mars Surface

The Twin Peaks are modest-size hills to the southwest of the Mars Pathfinder landing site. They were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997, and subsequently identified in Viking Orbiter images taken over 20 years ago. The peaks are approximately 30-35 meters (-100 feet) tall. North Twin is approximately 860 meters (2800 feet) from the lander, and South Twin is about a kilometer away (3300 feet). The scene includes bouldery ridges and swales or “hummocks” of flood debris that range from a few tens of meters away from the lander to the distance of the South Twin Peak.

In science fiction stories, Mars is the favourite home of aliens. No one has found any green Martians wandering over the planet. But many scientists believe that Mars may be the best place to look for simpler forms of life. Of all the planets in the Solar System, Mars is the most similar to Earth. Although it’s probably too cold for life to exist on the surface of Mars, it could exist in warmer pockets below ground. Micro-organisms could be living around hydro-thermal vents near the planet’s surface. In the past, Mars was a very different world. The Mars Global Surveyor probe found evidence that there was running water on the planet’s surface. This would have made the planet much more hospitable to life.

Mars is the most similar planet to earth in the solar system. It is therefore one of the first places to look when we are considering life on other planets. It is certainly one of the first places that science fiction writers have looked. Ever since H.G Wells wrote War of the Worlds, books and films have portrayed different images of martians and what their civilisation may look like. Now that we have visited Mars we know that there are no advanced races living on the red planet.
When the Viking Landers were sent to Mars in the 1970s they found a cold desolate dry world that seemed unlikely to be able to support life. With such cold temperatures, a thin atmosphere and no sign of liquid water the chance of finding even some sort of microscopic life forms seemed remote. Tests performed by both Viking landers seemed to back this up. However with the advance of astrobiology in recent years it is worth taking another look at those experiments.
The Viking landers carried several experiments designed to detect organic materials and organisms on the Martian surface. These experiments gave mixed results. While one experiment detected no organic compounds in the soil, another test known as the Labeled Release experiment (LR) found positive results. The LR was designed to drop a nutrient solution into a soil sample from Mars, and then measure the changes in the gaseous sample container to determine if the changes were organically induced (if bacteria were multiplying because of the nutrients they’d been given). When the experiment was conducted on both Viking landers, it gave positive results almost immediately. Most scientists on the Viking mission believed the positive results were attributed to the discovery of oxides in the soil, and that a chemical reaction occured when the nutrient solution was mixed with the oxides. However, the LR’s designer and principal investigator, Dr. Gilbert Levin, was convinced that his experiment found life.
Levin also says that the experiment which did not find organic materials in the soil were not sensitive enough to detect it in small amounts. This has been confirmed by NASA as possible. The experiment in question was tested in Antarctica and also found negative results, which was incorrect because there are organic materials there. This does not prove that the Viking landers found evidence of life. It means that the tests conducted were unsatisfactory.

Edward Witten
Edward Witten
Edward Witten (born August 26, 1951) is an American mathematical physicist, Fields Medalist, and professor at the Institute for Advanced Study. He is one of the world’s leading researchers in string theory (as the founder of M-theory) and quantum field theory. Witten is widely admired among his peers. This includes the renown 20th century geometer, Sir Michael Atiyah, who said of Witten, “Although he is definitely a physicist, his command of mathematics is rivaled by few mathematicians… Time and time again he has surprised the mathematical community by his brilliant application of physical insight leading to new and deep mathematical theorems… he has made a profound impact on contemporary mathematics. In his hands physics is once again providing a rich source of inspiration and insight in mathematics.” He also appeared in the list of TIME magazine’s 100 most influential people of 2004. He was mentioned in a 1999 episode of the cartoon Futurama. Witten has the highest h-index of any living physicist.
he h-index is an index suggested in 2005 by Jorge E. Hirsch of the University of California, San Diego to quantify the scientific productivity of physicists and other scientists based on their publication record. The index is calculated based on the distribution of citations received by a given researcher’s publications. Hirsch writes: A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np – h) papers have at most h citations each. In other words, a scholar with an index of h has published h papers with at least h citations each.The index is designed to improve upon simple measures such as the total number of citations or publications, to distinguish truly influential physicists from those who simply publish many papers; the index is also less sensitive to single papers that have many citations. The index works best for comparing scientists working in the same field; citation conventions differ among different fields. The h-index is calculable using free Internet databases and serves as an alternative to more traditional impact factor metrics which are available for a fee. Because only the most highly cited articles contribute to the h-index, its determination is a speedy process. Hirsch has demonstrated that h has high predictive value for whether or not a scientist has won honors like National Academy membership or the Nobel Prize. In physics, a moderately productive scientist should have an h equal to the number of years of service while biomedical scientists tend to have higher values.
Criticism
It is not difficult to come up with situations in which h may provide misleading information about a scientist’s output. Most importantly the fact that h is bounded by the total number of publications means that scientists with a short career are at an inherent disadvantage, regardless of the importance of their discoveries. For example, Evariste Galois’ h-index is 2, and will remain so forever. Had Albert Einstein died in early 1906, his h index would be stuck at 4 or 5, despite him being widely acknowledged as one the greatest physicists ever to have lived. Proposals to modify the h-index in order to emphasize different features have been made.
Based on the SPIRES HEP Database (Particle and High energy Physics, As of August 2005,):

  • Edward Witten: h = 132
  • John Ellis: h = 101
  • Steven Weinberg: h = 88
  • Dimitri Nanopoulos: h = 86
  • Cumrun Vafa: h = 85
  • Nati Seiberg: h = 84
  • Howard Georgi: h = 77
  • John Schwarz: h = 75
  • Frank Wilczek: h = 68
  • Lenny Susskind: h = 68
  • Mark Wise: h = 67
  • David Gross: h = 66
  • Andrew Strominger: h = 66
  • Roman Jackiw: h = 66
  • Stephen Hawking: h = 62
  • Joseph Polchinski: h = 58
  • Abdus Salam: h = 58
  • Tom Banks: h = 56
  • Sheldon Glashow: h = 53
  • Neil Turok: h = 50
  • Juan Maldacena: h = 49
  • Anthony Zee: h = 49
  • Michael Green: h = 44
  • Michael Peskin: h = 41
  • Gerard ‘t Hooft: h = 41
  • Alexander Polyakov: h = 38
  • Lisa Randall: h = 38
  • Steve Shenker: h = 36
  • Paul Frampton: h = 35
  • David Politzer: h = 34
  • Lee Smolin: h = 33
  • Brian Greene: h = 32
  • Shamit Kachru: h = 31
  • Eva Silverstein: h = 24
  • Richard Feynman: h = 23
  • Michio Kaku: h = 22
  • Gerald Cleaver: h = 20
  • Paul Dirac: h = 19