The facts of the matter
Just a note to point out several technical errors in an article in the Feb. 1999 Laser Focus World ("Martian science beckons tunable lasers," p. 28). I am Principal Investigator (MVACS Co-I) for both of the tunable-diode-laser (TDL) spectrometers on the MVACS payload and was involved in the early development of the TDL system for the microprobes described in that article. In paragraph 4 it is stated that "Folding mirrors in the TEGA [thermal and evolved gas analyzer] system will repeatedly ref
Just a note to point out several technical errors in an article in the Feb. 1999 Laser Focus World ("Martian science beckons tunable lasers," p. 28). I am Principal Investigator (MVACS Co-I) for both of the tunable-diode-laser (TDL) spectrometers on the MVACS payload and was involved in the early development of the TDL system for the microprobes described in that article. In paragraph 4 it is stated that "Folding mirrors in the TEGA [thermal and evolved gas analyzer] system will repeatedly reflect the probing beam back and forth through the soil..." This is not possible as the lasers operating at 1.37 µm and 2.05 µm could not actually penetrate any volume of soil. The soil is in fact heated in a remote oven and the evolved gases are carried into the multipass absorption cell via a stream of N2 carrier gas.
In paragraphs 5 and 6 it is stated that "Deep Space 2" is an MVACS experiment that will search for water and CO2 beneath Mars surface. Deep Space 2 (DS-2) is not an MVACS experiment, but was funded by NASA`s New Millennium program. Also, the DS-2 "microprobes" will not measure CO2 as they contain only a single laser operating at 1.37 ?m. The two TDL spectrometers that are part of the MVACS payload-one on the meteorological (MET) mast for atmospheric measurements (not mentioned in the article) and one serving as analyzer for the TEGA-do each contain two diode lasers for measurements of H2O and isotopic CO2.
Randy D. May (Randy.D.May@jpl.nasa.gov)Jet Propulsion Laboratory Pasadena, CA 91109
Putting Bose-Einstein condensates to the test I have read with great interest your editorial "My ten fearless predictions for 1999," (Laser Focus World, Jan. 1999, p. 228). Items 2 and 3 on your list touch closely on a new technology I am suggesting. The idea is to create nuclear fusion by starting with Bose-Einstein condensate of light atoms. A femtosecond laser then will irradiate the condensate. As the atoms in the condensate are colocated, it is hoped that the nucleus of two atoms can decondense into the same physical location, practically tunneling the coulomb potential barrier.
A paper published in the APS e-print Journal is available on http://publish.aps.org/eprint/gateway/epget/aps1998oct20_001/condensate.html. A letter to the editor was accepted by Fusion Technology and will be published in the May 1999 issue. I am now looking for organizations that could do the experiment and see if the physical phenomenon actually happens. I have talked with several friends of mine who are research physicists (I am a physicist myself but my line of work is fiber optics), and most say that they can not see a reason why it will not work. But in such a case the only way to be sure is to test the idea and see. The cost of the test is very small compared to the possible benefits. Herzel Laor (email@example.com) 2050 Hillsdale Cir. Boulder, CO 80303-5618
The real Bose-Einstein pioneers - Not to take anything away from the excellent work of Ketterle and his associates, but the first [pioneering efforts in] BECs were achieved in July of 1995 by Carl Wieman and Eric Cornell, together with their colleagues working at JILA, an interdisciplinary institute for research and graduate education jointly operated by NIST and the University of Colorado in Boulder (see Science 269, 198, 1995). Jim Faller Acting Div. Chief Quantum Physics Div., JILA Boulder, CO