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A28 SCIENCE
Wednesday 22 november 2017

Mars theory gets dusted: Streaks may be sand, not water

By MARCIA DUNN Geological Survey’s Colin study.
AP Aerospace Writer Dundas in Flagstaff, Arizo- To Meyer, this is what makes
CAPE CANAVERAL, Fla. (AP) na, measured 151 of these Mars so fun. Scientists have
— A new study suggests dark lines at 10 sites. Most long gone back and forth
that dark streaks on Mars of them end with slopes thinking of Mars as being
represent flowing sand — between 28 degrees and dry or wet depending on
not water. 35 degrees, a match for the most recent data.
Monday’s news throws cold active sand dunes on both “I still think that Mars poses
water on 2015 research Mars and Earth, according a great potential for having
that indicated that lines on to the researchers. A thin had life early on in its his-
some Martian slopes were layer of dust on top that tory,” Meyer said. “As long
signs of water currently on shifts and sometimes bright- as that’s true, we also have
the planet. Instead, Arizo- ens the surface might help a reasonable possibility of
na scientists report in Na- explain why these streaks life still being on Mars. It just
ture Geoscience that these seem to occur in the Mar- happens to be cryptic or
lines appear more like dry, tian summertime and then well hidden.”
steep flows of sand, rather disappear, only to reap- NASA currently has no rover
than water trickling down- This image provided by NASA shows the inner slope of a Martian pear the next year. — either at Mars or in de-
hill, at or near the surface. crater which has several of the seasonal dark streaks called If these lines are dry, “this velopment — capable of
“recurrent slope lineae,” or RSL, that a November 2017 report
If water is present, they said, interprets as granular flows, rather than darkening due to flowing suggests that recent Mars climbing such steep slopes.
it’s likely a small amount — water. has not had considerable That has engineers coming
and not conducive to life. Associated Press volumes of liquid water,” up with ideas like Martian
NASA, though, said the jury of water. But he acknowl- images of these so-called the researchers write. helicopters or drones.
is still out. edges, “It just may not be recurring slope lineae, or That’s key because water “But going from a clever
The lead scientist for NASA’s as exciting as the idea of RSL. Thousands have been in liquid form would be es- idea that works in your
Mars exploration program, rivers going down the sides spotted on Mars, from the sential to microbial life. sandbox to something that
Michael Meyer, points out of cliffs.” equator midway to each Dundas and his colleagues goes to Mars takes a fair
that the latest study does NASA’s Mars Reconnais- pole. stress that many questions amount of engineering de-
not rule out the presence sance Orbiter provided the The team led by the U.S. remain, demanding further velopment,” Meyer said.q

U.N. panel agrees to move ahead with debate on ‘killer robots’

By JAMEY KEATEN by such “killer robots” and this week included the The meeting falls under the have firmly staked out op-
Associated Press aired a chilling video illus- creation of legally bind- U.N.’s Convention on Cer- position to any formal ban.
GENEVA (AP) — A U.N. pan- trating their possible uses ing instrument, a code of tain Conventional Weap- The United States has taken
el agreed Friday to move on the sidelines of the first conduct, or a technology ons — also known as the a go-slow approach, rights
ahead with talks to define formal U.N. meeting of gov- review process. Inhumane Weapons Con- groups say.
and possibly set limits on ernment experts on Lethal The Campaign to Stop Killer vention — a 37-year old U.N. officials say in theory,
weapons that can kill with- Autonomous Weapons Sys- Robots, an umbrella group agreement that has set lim- fully autonomous, com-
out human involvement, as tems this week. of advocacy groups, says its on the use of arms and puter-controlled weapons
human rights groups said More than 80 countries 22 countries support a ban explosives like mines, blind- don’t exist yet but defining
governments are moving took part. of the weapons and the list ing laser weapons and exactly what killer robots
too slowly to keep up with Ambassador Amandeep is growing. Human Rights booby traps over the years. are and how much human
advances in artificial intelli- Gill of India, who chaired Watch, one of its members, The group operates by interaction is involved was
gence that could put com- the gathering, said partici- called for an agreement to consensus, so the least a key focus of the meeting.
puters in control one day. pants plan to meet again regulate them by the end ambitious goals are likely The United States argued
Advocacy groups warned in 2018. of 2019 — admittedly a to prevail, and countries that it was “premature” to
about the threats posed He said ideas discussed longshot. including Russia and Israel establish a definition. q