Ralph D. Lorenz Home Page

Updated March 2008

I have moved to

Space Department, Planetary Exploration Group

Johns Hopkins University Applied Physics Lab

11100 Johns Hopkins Road, MP3-E104, Laurel,

Maryland 20723-6099, USA

tel. 443-778-2903 fax. 443-778-8939

Books


New! R. Lorenz and J. Mitton
Titan Unveiled
Princeton University Press, April 2008
Buy from Amazon.com 		Harland and Lorenz
Space Systems Failures
Praxis/Springer,May 2005 Buy from Amazon.com 		Ralph Lorenz
Spinning Flight: Dynamics of Frisbees, Boomerangs, Samaras and Skipping Stones
Springer/Copernicus,Summer 2006 Buy from Amazon.com

R. Lorenz and J. Mitton Lifting Titan's Veil
Cambridge May 2002 Buy from Amazon.com 		Kleidon and Lorenz
NonEquilibrium Thermodynamics and the Production of Entropy
December 2004 Buy from Amazon.com 		Ball, Garry, Lorenz and Kerzhanovich
Planetary Landers and Atmospheric Entry Probes
Cambridge, March 2007 Buy from Amazon.com

Titan Bumblebee concept for a 1kg UAV to explore Titan EPSC08/ IPPW6 presentation . A paper with fill details was published in JBIS in 2008.

Titan's rotation reveals that it has an internal water ocean paper published in Science Magazine 21 March 2008.

Preprint of B. Stiles et al., Astronomical Journal, 2008 paper on measuring the rotation state of Titan from radar images. pdf

Dunes on Titan.! See paper published in Science Magazine 5 May 2006. Cassini RADAR image below

bigger version file. Large segment of T8 radar swath showing long dunes image A picture of me in the Pinacates dunefield in Mexico. I have processed some SIR-C Shuttle Imaging Radar data of Namibian dunes, perhaps the best terrestrial analogue jpg These same dunes are seen nicely in this Optical image taken by space shuttle astronaut with digital camera (see eol.jsc.nasa.gov)

Ralph with Huygens Probe at the European Space Operations Centre in Darmstadt, Germany for the Huygens descent to Titan (This is the SM2 test article, used in parachute trials from a balloon in Sweden in 1995)

Huygens lands on Titan!!

FOR CHARM TELECON.

A short video showing how the multipath interference pattern observed in the Huygens radio signal strength post-landing can be demonstrated with $10 of electronics using ultrasound. 2MB MPEG file. 0.5MB WMV file.

The sound of Huygens' dynamic descent.

A sound file made by encoding (specifically modulating the frequency of the tone with the strength of the radio signal) the strength of Huygen's signal as received by Cassini as a tone - the dynamic sound reveals the spin and swinging of the probe during its descent. 4MB WAV sound file. press release gives background info - see also UA News and ESA For trajectory reconstruction of a different kind, see paper on paper on frisbee dynamics

Ralph built the Huygens penetrometer (with help!!) in 1994. The penetrometer is part of the Huygens Surface Science Package (SSP) - John Zarnecki at PSSRI - The Open University in Milton Keynes, UK is the Principal Investigator. 10 years later, at -180 degrees C and nearly a billion miles from Earth, the penetrometer worked first time, recording the impact force over about 1/20 of a second as Huygens hit Titan at about 5 m/s at 13.45 CET on 14th January 2005. For further details and the preliminary interpretation ('creme brulee') see Datasheet on Huygens Penetrometer and Titan Result. and paper on the penetrometer detailed design.
Methane Rain on Titan.
Titan may have a hydrological cycle like Earth's, as evidenced by observations of changing clouds and river valley networks on Titan, but with methane as a working fluid. In Titan's low gravity, thick atmosphere environment, raindrops could be up to 9.5mm across and would fall at only about 1.5 m/s - about as fast as large snowflakes fall on Earth. For details see paper. (Plan. Space Sci, 1993). Note, that the tiny amount of sunlight reaching Titan's surface is not enough to drive a vigorous cycle - only on average 1cm per Earth year of rainfall - see Weather on Titan in Science Magazine (20 October 2000) However, since Titan's atmosphere can hold large amounts of methane, this low average rainfall may be manifested as massive once-in-a-century downpours.....(this paradigm also fits with the relatively small cloud cover percentage on Titan, which can be predicted by a heat engine theory, see paper. published in GRL just prior to the Huygens encounter). My book on Titan,

Lifting Titan's Veil

written with Jacqueline Mitton, is published by Cambridge University Press and received excellent reviews in the scientific press - see, e.g. reviews in EOS , Science , Endeavour and Earth,Moon and Planets.

You can order it directly from the publisher although I've found it's cheaper to buy from Amazon.co.uk or (in the USA) Buy from Amazon.com

For papers on Titan, see publications list below. For radar images of Titan, go here

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webmail

New items

Revised publications list

See paintings by my sister Kirsty (we're twins)

Ralph's Frisbee Research

Tucson Observing Weather

BBQ Chicken recipe

Pictures (including curling), Scotland December 2003

Pictures from Japan, December 2003

Pictures from falconry trip in Scotland, August 2003

Artist's impressions of Titan

Article in Science Magazine The Glitter of Distant Seas" on the detection with the Arecibo radar of lakes/seas on Titan

Article in Science Magazine < Full Steam Ahead, Probably> on the Statistical Mechanics approach to Maximum Entropy Production in the climate system

Pictures from holiday in Scotland, Christmas/New Year 2002

Beyond Daisyworld workshop picture

LPL Fieldtrip to Mt St Helens, Channeled Scablands and Colmbia River Basalts Pictures (large)

Article in Astronomy.com on Titan's Tidal Winds

Article in Astronomy.com on December 2001 Titan Occultation

Article in Astronomy.com on Arecibo Radar Observations of Iapetus

IDL code for HST basemap on which to overlay Cassini observing plans

Pictures from trip Vannes (France) and Dollar (Scotland), April 2002

Pictures from holiday in Scotland, Christmas/New Year 2000

Amateur Titan Spectroscopy/Photometry science rationale (pdf)

A survey of types of useful amateur observations of Titan (pdf)

Paper from Planetary and Space Science on amateur observations (pdf) ...

Article on Weather on Titan in Science Magazine (20 October 2000)

Roof Tests of Huygens SSP tilt sensors on DISR tilt/spin table

Cassini Earth Swingby Radar Observations of the Eastern Pacific and South America

Video Astrophotography Images

Datathief in IDL

Other stuff

Ralph's Spacecraft Impact Penetrometry Page

Current Activities

Pictures from a flight around Tucson

'Death of a Watery World' Article on Mars in New Scientist

Pictures of impact geology and wildlife from trip to South Africa

Digital Pictures from the LPL fieldtrip to Yellowstone National Park Geology and People

Digital Pictures from the fieldtrip at the recent Giant Meteorite Impact conference in Sudbury, Canada

Digital Pictures from the Paris Air Show and recent trip to Mount Saint Helens.

Other Stuff

Recent Projects

  • Modelling of lava flows and thermal emission on Io
  • Design Study of Deep Jupiter Probes (under JPL Contract)
  • Analysis of HST Images of Titan (with Peter Smith and Mark Lemmon )
  • Titan observed by HST at a variety of wavelengths: 336nm (UV), 439nm (Blue) 547nm (Green) 588nm (Orange) 673nm (Red) and 889nm (Near-IR methane band). The colours above aren't quite right (as you wouldn't be able to see the first and last image!) but help to make a mental connection between appearance and wavelength.
  • Image looks best with squared data numbers to enhance contrast. Also available, straight data numbers or cubed for extreme contrast. The variation of limb-darkening is apparent - in the UV the disk is flat, like our Moon, while at visible wavelengths it is more like a Lambertian scatterer. The North-South asymmetry (which varies with season) is strongest in the blue, but small in UV and red. The methane band has the asymmetry reversed.

    Previous Projects