The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes

Lorenz, Ralph D.; Wall, S. D.; Radebaugh, J.; Boubin, G.; Reffet, E.; Janssen, M. A.; Stofan, E. R.; Lopes-Gautier, R.; Kirk, Randolph L.; Elachi, C.; Lunine, Jonathan I.; Mitchell, K. L.; Paganelli, F.; Soderblom, Laurence A.; Wood, Charles A.; Wye, L.; Zebker, H. A.; Anderson, Y.; Ostro, S. J.; Allison, M.; Boehmer, R.; Callahan, Philip S.; Encrenaz, P.; Ori, G. G.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, Wesley L.; Kelleher, K.; Muhleman, D. O.; Picardi, G.; Posa, F.; Roth, L. E.; Seu, R.; Shaffer, S.; Stiles, B.; Vetrella, S.; Flamini, Enrico; West, Richard

doi:10.1126/science.1123257

Cited by 355 publications

(304 citation statements)

References 18 publications

Supporting

Mentioning

290

Contrasting

Order By: Relevance

“…Ontario Lacus near the southern pole (Wye et al, 2009), this same interpretation of the specular echoes from near-equatorial regions seems unlikely as no lake features have been observed in Cassini RADAR imagery of these areas and instead extensive dune fields are often seen (Lorenz et al, 2006). In addition, specular reflection of sunlight from a liquid surface has been seen from a high northern latitude area (Stephan et al, 2010), however a wider search including lower latitudes have not detected any such glints (Porco et al, 2005).…”

Section: Lon (Deg)mentioning

confidence: 99%

“…Observations of the high abundance of methane in its nitrogen atmosphere led to suspicion that there might be a surface-atmosphere methane cycle similar to Earth's water cycle (Owen, 1982;Atreya et al, 2006). New evidence, particularly from Cassini, demonstrates this is truer than was expected with observations providing evidence for wind processes (Radebaugh et al, 2008;Lorenz et al, 2006), continuing erosion Barnes et al, 2007b;Elachi et al, 2006), clouds (Brown et al, 2002;Griffith et al, 1998), and even apparent liquid bodies (Stofan et al, 2007). Changes due to an active methane cycle (Turtle et al, 2009) and possible recent cryovolcanic activity (Lopes et al, 2007;Wall et al, 2009) further strengthens the Earth-like parallels.…”

Section: Introductionmentioning

confidence: 99%

“…Some interesting features of the dataset are then discussed, namely those containing strong and variable specular echoes, and data from periods when the sub-Earth track passed over Cassini SAR imagery swaths. One of those Cassini tracks (T8) included extensive areas of sand dunes (Lorenz et al, 2006) while several (T13, T41, T43, T44) passed over Xanadu Regio.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ground-based radar observations of Titan: 2000–2008

Black

Campbell

Carter

2011

Icarus

View full text Add to dashboard Cite

Section: Lon (Deg)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ground-based radar observations of Titan: 2000–2008

Black

Campbell

Carter

2011

Icarus

View full text Add to dashboard Cite

“…However, the polar clustering might also be related to higher precipitation at the poles (Rodriguez et al, 2009;Brown et al, 2010;Rodriguez et al, 2011) relative to the dunefilled equatorial desert (Lorenz et al, 2006;Radebaugh et al, 2008;Le Gall et al, 2011;Rodriguez et al, 2014), which may be caused by circulation (Rannou et al, 2006;Friedson et al, 2009). The lower elevations of the poles relative to equatorial regions may also play a role (Iess et al, 2010;Lorenz et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

Ádámkovics

Mitchell

Hayes

et al. 2016

Icarus

View full text Add to dashboard Cite

The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5 µm (H-band) were performed during the same night using instruments with adaptive optics at both the W. M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, R = λ/∆λ ≈ 1, 500, while the Keck observations were performed with NIRSPAO near 1.5525 µm at higher resolution, R ≈ 25, 000. The moderate resolution observations are used for flux calibration and for the determination of model parameters that can be degenerate in the interpretation of high resolution spectra. Line-by-line calculations of CH 4 and CH 3 D correlated k distributions from the HITRAN 2012 database were used, which incorporate revised line assignments near 1.5 µm. We fit the surface albedo and aerosol distributions in the VLT SINFONI observations that cover the entire H-band window and used these quantities to constrain the models of the high-resolution Keck NIRSPAO spectra when retrieving the methane abundances. Cassini VIMS images of the polar regions, acquired on 20 July 2014 UT, are used to validate the assumption that the opacity of tropospheric aerosol is relatively uniform below 10 km. We retrieved methane abundances at latitudes between 42 • S and 80 • N. The tropospheric methane in the Southern mid-latitudes was enhanced by a factor of ∼10-40% over the nominal profile that was measured using the GCMS on Huygens. The Northern hemisphere had ∼90% of the nominal methane abundance up to polar latitudes (80 • N). These measurements suggest that a source of saturated polar air is equilibrating with dryer conditions at lower latitudes.

show abstract

“…Atmospheric haze settles on the surface [135]. Wind drives the formation of giant sand dunes [80]. Rain erodes mountains [8].…”

Section: Cassini-huygens Discoveriesmentioning

confidence: 99%

AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance

et al. 2011

View full text Add to dashboard Cite

We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVI-ATR). With independent delivery and direct-to-Earth communications, AVI-ATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments-2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector-AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earthyear nominal mission. We propose a novel 'gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead

show abstract

The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes

Cited by 355 publications

References 18 publications

Ground-based radar observations of Titan: 2000–2008

Ground-based radar observations of Titan: 2000–2008

Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance

Contact Info

Product

Resources

About