Moons and Icy Worlds: October 2011

The Europa Science Definition Team (SDT) has been tasked by NASA Headquarters to consider a lander option for Europa. As part of the information gathering effort, the Europa SDT will solicit input from the scientific community at large. A Town Hall meeting consisting of presentations and discussion is scheduled for the afternoon immediately following the upcoming OPAG meeting in Pasadena, on Thursday October 20, from 1:30 to 5:00 pm. Please see:

Details from recent lander design studies will be presented, followed by community presentations and open discussion. Brief presentations are solicited relating to topics such as: potential science objectives and priorities, instrument techniques, landing environment and sites, sample handling, and astrobiological context.

Requests for brief (~5-minute) presentations on relevant topics will be accepted until the week of the event.

Interested parties unable to attend in person are encouraged to join electronically. Video conferencing details may be found at the OPAG web site:

Note that registration for OPAG does not confirm participation in the Forum.

Please forward questions or RSVP to Steve Vance (

Comparative Survival Analysis of Deinococcus Radiodurans and the Haloarchaea Natrialba Magadii and Haloferax Volcanii, Exposed to Vacuum Ultraviolet Irradiation

Ximena C. Abrevaya, Ivan G. Paulino-Lima, Douglas Galante, Fabio Rodrigues, Pablo J.D. Mauas, Eduardo Corton, Claudia de Alencar Santos Lage
(Submitted on 29 Sep 2011)

The haloarchaea Natrialba magadii and Haloferax volcanii, as well as the radiation-resistant bacterium Deinococcus radiodurans, were exposed to vacuum-UV (V-UV) radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Cell monolayers (containing 105 - 106 cells per sample) were prepared over polycarbonate filters and irradiated under high vacuum (10-5 Pa) with polychromatic synchrotron radiation. N. magadii was remarkably resistant to high vacuum with a survival fraction of ((3.77 ± 0.76) x 10-2), larger than the one of D. radiodurans ((1.13 ± 0.23) x 10-2). The survival fraction of the haloarchaea H. volcanii, of ((3.60 ± 1.80) x 10-4), was much smaller. Radiation resistance profiles were similar between the haloarchaea and D. radiodurans for fluencies up to 150 J m-2. For fluencies larger than 150 J -2 there was a significant decrease in the survival of haloarchaea, and in particular H. volcanii did not survive. Survival for D. radiodurans was 1% after exposure to the higher V-UV fluency (1350 J m-2) while N. magadii had a survival lower than 0.1%. Such survival fractions are discussed regarding the possibility of interplanetary transfer of viable micro-organisms and the possible existence of microbial life in extraterrestrial salty environments such as the planet Mars and the Jupiter's moon Europa. This is the first work reporting survival of haloarchaea under simulated interplanetary conditions.

Full paper

Comments: Draft version (without figures), Accepted for publication in Astrobiology
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Citeas: arXiv:1109.6590v1 [astro-ph.EP]
Submission history
From: Ximena Celeste Abrevaya [view email]
[v1] Thu, 29 Sep 2011 17:02:52 GMT (131kb)