Download Issue number 138 - spring 2011

Phys13news
UNIVERSITY OF
WATERLOO
Department of Physics & Astronomy
University of Waterloo
Waterloo, Ontario, Canada
N2L 3G1
Spring 2011
Number 138
The Search for Extra-Terrestrial Life
Cover:
The Search for life on other worlds.
Contents
The NASA Kepler Mission: a Search for ExtraSolar
Planets…………………………….....………………….3
How will we find other planets similar
to our own? This article will tell you
about the latest findings from the
Kepler mission.
Communicating
about
the
Discovery
of
Extraterrestrial Life: Different Searches, Different
Issues………............................................................……6
Our excitement concerning the possible discovery of life
on other worlds can perhaps cause us to forget about how
it will impact our society. This article by SETI
researcher Margaret Race provides an overview of the
implications of detecting alien life.
The New Biochemistry...………….……………....….12
We usually think of arsenic as poisonous. Could it form
the foundation for alien life?
Puzzles, Problems and Solutions
Crossword – Mostly Optical.………………...………14
SIN BIN……….........….....….….15
From the Editor
Are we alone? Is Earth the only life-supporting
planet in the universe? Does intelligent life exist outside
of our solar system? Although these questions have
fascinated humankind for centuries, it is only in the last
few decades that a substantive amount of scientific
research has been devoted to this question.
The theme of this issue of PHYS13 is on the
search for extraterrestrial life. Dr. Sylvie Beaulieu, a
postdoctoral fellow in our Astronomy group at the
University of Waterloo, is the author of an article that
describes the most up to date findings from the Kepler
mission. Over 200 new planets have been discovered
over the past 10 years – will one of them be Earth-like?
Dr. Margaret Race, a researcher at the SETI institute in
the United States, has written an article based on a
presentation she gave at the International Astronautical
Conference in Vancouver in 2004. In it she discusses
the relationship between scientific discoveries that
might point to the existence of extra-terrestrial life and
societial implications that would follow. A slightly
longer version article first appeared in Acta
Astronautica 62 (2008) 71–78, and is reproduced here
in abridged form with permission.
Our student corner features an article by Kathryn
Scannel, an undergraduate student at the University of
Waterloo. Relying on her previous degree in biology,
Kathryn provides an introductory discussion of the
possible finding of alien life on Earth. What might that
mean? You’ll have to read the article to find out.
Robert Mann
Phys13news is published four times a year by the
Department of Physics and Astronomy at the University
of Waterloo. Our policy is to publish anything relevant
to high school and first-year university physics, or of
interest to high school physics teachers and their senior
students. Letters, ideas and articles of general interest
with respect to physics are welcomed by the editor. You
can reach the editor by paper mail, fax or email.
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Phys13news
Department of Physics and Astronomy
University of Waterloo
Waterloo, ON N2L 3G1
519-746-8115
[email protected]
Editor:
Robert Mann
Editorial Board:
N. Afshordi, B.-Y. Ha, D. Hawthorn,
R. Melko, K. Resch
Publisher: Judy McDonnell
Printing: UW Graphics
Phys13news / Spring 2011
Page 2
The NASA Kepler Mission: a Search for
ExtraSolar Planets
by Sylvie F Beaulieu
We have all wondered at one time in our life if
planet Earth, the only habitable planet in our Solar
System, is unique in the sense that it is the only known
planet able to sustain life as we know it. With our own
galaxy the Milky Way containing between 100 and 400
billion stars, it is thus understandable to wonder if our
Solar System and planet Earth are unique. With so many
stars in a galaxy, and with billion of galaxies in the
Universe, the probability of other stars harbouring a
planetary system is quite high. In fact, computer models
estimate that the Milky Way could contain up to 50
billion extra-solar planets (a.k.a. exoplanets).
Detection Methods
Finding extrasolar planets i.e. planets orbiting
stars other than our own star the Sun, is not an easy task
because stars are intrinsically very bright compared to
planets.
Over the years, exoplanet hunters have
developed a few methods to help them detect planets
orbiting nearby stars. Some methods like pulsar timing,
astrometry, gravitational lensing, and the detection of
circumstellar disks can provide hints for the presence of
objects massive enough to be called planets. But, three
methods have proven to be very effective, although still
challenging, at detecting the presence of planets. One
method is actually able to image planets for the first
time. Lets have a look at those three methods. The first
one called the transit method consists of measuring the
star brightness for long periods of time. Eventually, if an
object is at least the size of Earth, it is possible to detect
fluctuations i.e. a dip in the brightness caused by the
passage of that object in front of the star (Fig. 1). In
order to confirm a detection, several transits of that star
must be recorded to rule out normal variations in the
brightness of the star. The second method called radial
velocity consist of measuring fluctuations in the radial
velocity of the star that could be caused by the
gravitational influence of an object orbiting that star. In
short, the method tries to detect any wobbling in the
movement of the star. A third method which consist of
actually imaging planets (as oppose to infer the presence
of an object) uses a technique called Angular
Differential Imaging (ADI) combined with an adaptive
optics system. This very promising method was
developed in 2003 by a team led by Dr Christian Marois
(at the time at Université de Montréal, now at NRC
Herzberg Institute of Astrophysics, Canada). This
method eventually led the team to the discovery of the
first imaged exoplanetary system around the nearby star
HR8799 (see http://www.gemini.edu/threeplanetspr).
The Kepler Mission
What is the perfect recipe to form a system of
planets orbiting a star which would produce at least one
habitable planet such as planet Earth? Does the star
needs to be of the same spectral type as the Sun? What
kind of planets can we expect to find, and how many?
Could there be more than one habitable planet in a
system?
The Kepler Mission is a NASA project designed
and dedicated to observe a specific set of stars which
may lead to the discovery of extrasolar planets, and
more specifically habitable planets, i.e. planets that
orbits in the “habitable” zone. Such planets are more
likely to sustain some form of life. The wealth of data
produced by this mission may enable astronomers to
answer some of the questions highlighted earlier.
Fig. 1: The passage of an object in front of the star will create a dip in the brightness of the star.
Phys13news / Spring 2011
Page 3
To accomplish its task, the Kepler mission uses
the transit method. Principal investigator William
Borucki (NASA AME Research Center) leads a large
team of coinvestigators and project scientists whose
duties are to analyze the data.
The Kepler observatory (Fig. 2) is a Schmidt
telescope with an aperture of 0.95 meter (the diameter of
the mirror) and a 105 square degree field-of-view on the
sky (from Earth, the apparent diameter of the moon is
half a degree on the sky). Its detector is a photometer
made of an array of 42 Charged Couple Devices (CCDs)
(Fig. 3). Each CCD is composed of 2200 x 1024 pixels.
The telescope was launched on 6 March 2009 and was
placed on a heliocentric orbit. The mission is scheduled
to last 3.5 years but is designed to be able to continue for
up to 6 years.
When the search for extrasolar planets became
more realistically feasible, it was thought that only solar
(or near solar) type stars (main-sequence stars of the
spectral type F, G, and K) would be the most likely
candidates to have planetary systems. So, all surveys tend
to concentrate on stars from those categories.
the orbit of an exoplanet which would be at ≈ 5 AU
(Astronomical Unit) from its parent star (the distance
between the Sun and Jupiter). So, we tend to find more
exoplanets very close to their parent star because their
orbital time is much shorter, i.e. in the order of days, or
sometimes, hours.
What Kind of Planets are Found, and How Many
As of February 2011, Kepler has discovered 1235
planet candidates. Candidates are then scheduled for
follow-up observations with ground-based telescopes in
order to confirm their status as planets or rule them out as
false detection. Fig. 5 illustrates the mass versus orbital
distance of the first five discovered planets (red circles).
This cartoon illustrates the position as well as the mass of
these newly discovered planets compared to the planets
of the Solar System. The habitable zone is shown by the
green band, and the yellow points are the 400 known
exoplanets found in previous ground-base surveys as of
December 2009. By February 2011, there were 15
confirmed planets. A more extended and detailed
Fig. 3: The 42 CCDs array which constitute the main detector
of the photometer.
Fig. 2: Cartoon illustrating the Kepler Observatory.
The observation schedule of Kepler is set up to
observe two very specific patches of the sky toward the
constellations of Cygnus and Lyra for the duration of the
mission i.e. 3.5 to 4 years minimum. Kepler’s detector
image a section of Cygnus and Lyra (Figure 4) (over 100
000 main-sequence stars) every 30 minutes in order to
detect any fluctuations in the brightness of every stars.
To confirm a true transit caused by the passage of a
planet, as oppose to a normal variation in the star’s
brightness, a transit must be observed a few times. Of
course, the smaller the planet, the more challenging it is
to detect a transit. This is why Jupiter-like planets are
more often detected than Earth-like planets. It takes about
12 years of repeat observations to be able to determine
Phys13news / Spring 2011
list of the 15 discovered planets by Kepler can be found
on NASA Kepler website (see below for the website
link). The list provides details such as the planetary
characteristics and orbit, and the stellar characteristics for
each confirmed planets. On January 2011, the Kepler
team announced the discovery of its first rocky planet,
and the smallest planet outside of our Solar System.
Kepler-10b is 1.4 times the size of planet Earth, and 4.6
time its mass. This discovery demonstrates the capability
of Kepler to detect Earth-like planets.
In addition to searching for exoplanets, the survey
yielded new discoveries of objects such as pulsating stars
and eclipsing binaries during the asteroseismology
survey phase of the mission. Such survey was necessary
in order to separate pulsating stars from stars that may
have orbiting planets.
What is a Planet?
Since the mid 1990s, increasing discoveries of
objects situated in the Kuiper Belt (a region of orbiting
Page
4
materials beyond Pluto’s orbit) led the planetary
astronomers to question the then current definition of
what constitute a planet. On 24th August 2006, during
the general assembly of the International Astronomical
Union (IAU) in Prague, a new definition for “planet” was
adopted. In a nutshell, to be defined as a planet, a
celestial body must 1] be in orbit around the Sun, 2] have
sufficient mass for its seft-gravity to overcome rigid body
forces so that it assumes a hydrostatic equilibrium (near
round) shape, and 3] have cleared the neighbourhood
around its orbit. Following this new definition, Pluto was
re-classified as “dwarf planet” because of its size, and
because its orbit is situated near other similarly-sized
objects (e.g. Eris and Sedna) in the transneptunian
region. Pluto is thus considered a Kuiper-belt object and
constitutes its largest member, to this date.
This new definition led to the demotion of Pluto
from “planet” to “dwarf planet”. Such redefinition of the
word “planet” is not new. The word “planet” (from
Greek) means “wandering star”. As more exoplanets are
discovered, surely the definition of what constitute a
planet will continue to evolve in time.
You wish to learn more?
NASA provides a very nice website dedicated to
the Kepler Mission. In addition to a collection of
information about the mission, you will find sections on
multimedia and education with a range of animations,
movies, and classroom activities. The multimedia section
has an interactive program called Kepler Exoplanets
Transit Hunt. This is a fun and intuitive animation which
walks you through the various steps, taken by exoplanets
hunters, to discover extrasolar planets and to measure
their parameters. Weblink to the Kepler Mission:
http://kepler.nasa.gov/
Fig. 4: Overlay of Kepler’s field-of-view on the sky area being
monitored during the mission.
Acknowledgements:
All pictures in this article are drawn from the
NASA Kepler Mission website.
Sylvie Beaulieu is a HIFI Instrument Support Scientist in the
Dept. of Physics and Astronomy at the University of Waterloo.
She can be reached at: [email protected]
Fig. 5: Mass versus orbital distance of planets and exoplanets. The red dots
are the first five exoplanets discovered by Kepler. The yellow dots are
known exoplanets from previous ground-base survey.
Phys13news / Spring 2011
Page 5
Communicating about the Discovery of
Extraterrestrial Life: Different Searches,
Different Issues
by Margaret S. Race
context of both science and types of societal
ramifications. When ET life and searches are viewed
from this broad perspective, it is possible to untangle the
implications of different searches, reveal the relevant
issues in legal, policy, practical, ethical/theological
realms, and anticipate the potential impacts on
humankind at present and in the decades to come.
Introduction
Distant Searches for ETI and Extrasolar Planets
Finding credible evidence for the existence of
extraterrestrial (ET) life would be significant news for
both the scientific community and the public at large.
Managing the communication of such a dramatic
discovery would be an unprecedented challenge for
scientists, government agencies, and the mass media. The
1997 announcements about presumed fossil life in the
martian meteorite ALH84001 provided a dress-rehearsal
of sorts for the kinds of frenetic questioning and
excitement that are likely to accompany verifiable
evidence for ‘ET’ life. With astrobiological exploration
and research proceeding on so many fronts worldwide, it
is wise to consider well in advance how communication
about extraterrestrial life will be handled. Along with
information about the discovery itself, it will be
necessary to convey the implications of discovery from
multiple perspectives—scientific and otherwise—and to
clearly distinguish the type of ET life that may be
involved. The need for communicating this complexity is
obvious if one analyzes the impressive range of scientific
efforts currently involved in the search for ET life.
Astrobiological searches for ET life encompass a
broad spectrum of scientific research efforts [1]. In
general, this multidisciplinary field seeks evidence of life
(not necessarily life itself), searching everywhere we can
explore, using diverse scientific methods. At present, the
research and exploration can be viewed in three general
categories:
(1) ‘SETI’ searches for messages from intelligent ET
civilizations
(2) Exploration for extrasolar and/or habitable planets
(3) ‘Exobiology’ research and missions within the solar
system.
Each looks in different locations, using different
scientific instruments and methods, and gathers different
types of evidence and data (Table 1). Not only are there
significant differences in search methods and locations, it
is important to recognize that the nature of presumed ET
life and the scientific meaning of a discovery are likewise
quite distinct (Table 2).
All these distinctions must be borne in mind when
preparing for public communication because of their
relevance to broad societal implications of future
discoveries in the short and long terms. In preparation for
managing the communication of a discovery, it is
instructive to systematically compare and contrast the
features of the different searches and examine them in the
Phys13news / Spring 2011
For millennia, humans have wondered whether our
species and home planet are unique. With modern
advances in astronomical understanding and technology,
searches are underway to scan the far reaches of space in
an organized fashion for evidence of other life. In
particular, searches for extraterrestrial intelligence (ETI)
and extrasolar planets are each conducted using
telescopes that scan locations light years away and
outside the solar system. Both involve the collection of
data in the form of ‘signals’ conveying indirect or remote
information relevant to ET life.
In the case of SETI, the focus is on
electromagnetic signals or messages. In searches for
extrasolar planets, it is on measurements of wobbles,
transits or interferometer data identifying the presence,
size and characteristics of other planets as well as their
location within their solar system. Because the data are
collected remotely and with no direct interactions with
the target bodies, there are no special procedures or
regulatory controls imposed upon the searches during
exploration. In fact, there are no specific treaties or laws
directly relevant to either exploration effort, except
perhaps those that involve the construction of telescopes
or facilities in particular locations on Earth.
The nature of and evidence for ET life differs
markedly between these two systematic search efforts.
By definition, if ETI signals are discovered, they will be
presumed to emanate from an intelligent and advanced
civilization, capable of deliberately devising technologies
that can send detectable signals beyond their home
location. Even if we detect and verify a signal, we will be
unable to know details about the nature of the life form
or its biochemistry and physiology, or whether it even
persists at present.
Likewise, while positive indications for a
‘habitable’ extrasolar planet could convey exciting
information about earth-like planets with possible
biogenic atmospheres potentially conducive to life as we
know it, we are unlikely to know much about the
persistence or type of organisms or the biochemical
processes behind observed phenomena. For both SETI
and extrasolar planet exploration, even if additional
studies and searches are undertaken to learn more about a
particular discovery, they are unlikely to yield a full
understanding about the newly discovered life forms or
result in direct experience or interaction with them.
Page
6
Exobiological Searches within the Solar System
In contrast, exobiological searches encompass a
diversity of search types and activities that are
comparatively nearby—either Earth-based or conducted
within the solar system—all of which gather real-time
information relevant to life and celestial locations. For
the sake of this discussion, the range of search types fall
roughly into three distinct types: (1) space exploration,
missions and associated research, (2) studies of
meteorites and materials delivered to Earth by natural
influx, and (3) experiments and laboratory studies related
to cosmochemistry and the origin of life.
In exobiology, while some of the data are
collected remotely as signals of various sorts (Images,
Phys13news / Spring 2011
remote sensing, spectral analyses, etc.), considerable data
are gathered in direct fashion through experiments,
sample collection, roving, digging, drilling, lab
experimentation, etc., thus involving situations with
potentially direct impacts or interactions. The various
types of exobiological searches for ET life gather
evidence in the form of physical/chemical, geological,
biological, structural, and molecular data, not unlike
routine scientific studies on Earth.
Because of the range of research types, there are
like-wise a variety of possible discovery scenarios. For
example, a robotic rover or lander that transmits the
information to Earth could find evidence for microbial
ET life on Mars; so too could future astronauts on the
martian surface who might come in direct contact with
Page 7
ET life. Alternatively, it could be discovered on Earth, in
a containment laboratory where returned samples are
examined, or inside meteorites or other collected
extraterrestrial materials. In the extreme, the chemical
evolutionary process leading to ET life formation might
be duplicated artificially in the lab through various
experiments with mixes of interplanetary organic
molecules in environmental conditions simulating the
early Earth. Researchers are also seeking to create life or
self-replicating molecules in the laboratory. Thus the
nature of ‘exobiological’ searches, with varied discovery
scenarios and research types, raises questions about
possible cross contamination and scientific risks that are
not found in either SETI or extrasolar planet searches.
Even during the process of exploration prior to the
discovery of ET life, there are regulatory and practical
implications for exobiology in the form of planetary
protection controls for missions or environmental, health
and safety (EHS) regulations on Earth. Space-craft and
missions to locations in the solar system are governed by
policies outlined in The Outer Space Treaty of 1967 [2]
which stipulates that exploration must be done in a
manner that avoids harmful cross contamination in the
form of either forward contamination of the target body
by hitchhiker terrestrial microbes, or back contamination
of Earth by extraterrestrial materials or samples upon
return [3]. In addition to the specific directives and
controls imposed by particular launching agencies or
countries in accordance with the OST and the
international Committee on Space Research (COSPAR),
there are a complex array of routine environmental,
health and safety laws and regulations that may also
apply to the research and activities conducted in Earthbased labs [4].
Exobiology builds upon a vast array of direct
knowledge about living systems, their metabolism and
biological signatures, combined with extensive
information about celestial bodies and processes in the
solar system. Based on our current knowledge of life on
Earth and conditions in the solar system, we can surmise
that ET life is likely to be microbial and found in places
with conditions amenable for liquid water to exist, either
persistently, transiently or in the recent past. If microbial
ET life is found in situ by robotic spacecraft or astronauts
visiting new locations, more than its existence can be
verified in real time. Through direct studies, it will be
possible to determine whether it shares DNA and Earthlike bio-chemistry, and whether and how it may be
related to the current three-domain view of life on Earth.
Moreover, if it has a distinct biochemistry unrelated to
life as we know it, we will have direct opportunity to
study the life in detail, either on Earth or in its native
location to characterize it more fully.
Earth based studies of meteorites also contribute
direct information relevant to the nature of ET life.
Already debates about alleged fossil life in the meteorite
Phys13news / Spring 2011
ALH84001 have spurred extensive research on
extremophiles, nanobacteria, and comparative topics
relevant to ET life. If perchance an extant or dormant life
form were discovered in a meteorite, it would be possible
to conduct direct studies of its nature and biochemistry,
comparing it with important features of life on Earth.
Likewise, laboratory research on cosmochemistry offers
insight into the nature of early life by seeking to re-create
the conditions and molecular mix of precursor molecules
that may have lead to life as we know it. If for example, a
Miller–Urey type of experiment or a laboratory impact
simulation show evidence for initiation of a replicating
process based on organic life forms, it would allow direct
comparison with present day living systems and address
questions about whether life is a cosmic imperative.
Such a finding would transform our views of the
universe, suggesting the potential for life to arise
repeatedly whenever and wherever initial conditions are
suitable [5]. Whether exobiological evidence for ET life
is gathered on Earth or elsewhere in the solar system, a
discovery could quickly generate far more direct data and
understanding of the nature of life than other search
types. Neither ETI nor extrasolar searches could
conceivably yield the opportunity for such
comprehensive analysis of an ET discovery. As
importantly, an exobiological discovery of ET life would
also prompt discussion of broad societal implications that
are immediately more complicated than those associated
with search types outside the solar system.
The Full Implications of Discovery
Discovery and verification of the existence of ET
life will be extraordinarily profound scientifically, but
mere scientific knowledge about the existence of ET life
per se is not what determines its meaning and
implications for humankind. To understand the full
impact of a possible ET discovery, we must extend
beyond the scientific discovery itself and consider the
nature of the presumed life as well as the potential for
human actions or plans to cause impacts on it or from it.
For comparison, it was not the scientific knowledge
about inheritable traits or the discovery of DNA’s
structure that had meaning or implications for
humankind, but rather the subsequent uses and
applications of the information through deliberate actions
such as selective crop and livestock breeding, eugenics,
genetic engineering and biotechnology. When and if we
learn that we are not alone in the universe, we should be
prepared similarly to communicate about the full
implications.
As shown in Table 3, the societal, policy, legal,
ethical, theological implications of a ‘discovery’ are
distinctly different for the various search types. For the
most part, our current consideration of the impacts
focuses primarily on near term actions taken by
governments and launching agencies. In the longer term,
Page 8
it will be necessary to consider implications more
broadly, including such perspectives as the individual,
private sector and even the extraterrestrial life types
themselves. As mentioned earlier, already there are
considerable differences in policies and oversight for the
three major search types during the exploratory period;
extrapolating to the post-discovery phase, the issues get
even more complicated.
When it comes to anticipating the discovery of ET
life, the SETI community is alone in having conducted
serious international discussions of how to respond if and
when a signal from ETI is detected. A set of “SETI
Principles” were developed over a period of years and
approved by the SETI Committee of the International
Academy of Astronautics (IAA) in 1989. The
Declaration of Principles is not legally binding and has
no enforcement provisions, but it has been endorsed by
numerous major organizations [6].
Rather than presuming anything about ET life
itself, the SETI Principles focus instead on the human
response anticipated in the face of a discovery scenario,
providing step-by-step operational guidelines for
verifying the signal, sharing information openly, and
consulting broadly and internationally prior to making
contact in the form of a return message. Already
researchers have identified a number of anticipated
implementation problems likely to arise upon discovery,
despite the existence of the SETI Principles. These
Phys13news / Spring 2011
include problems with the level and type of
organizational readiness [7], the limited discovery
scenarios considered [8], and a lack of preparations for
mass media communications [9,10].
Despite the shortcoming of the SETI Principles,
they represent the only organized attempt to codify
guidelines and policies about what to do upon discovery.
For extrasolar planet searches, while there are no current
or anticipated policies related to the discovery of ET
biogenic atmospheres or locations, it is likely that none
are needed. This is mainly because the nature and
distance of possible discoveries all but preclude
significant practical concerns, except perhaps the sharing
of scientific information.
The same cannot be said of other search types.
There are currently no policies or recommendations
applicable to the discovery of non-intelligent life,
whether on Earth or other solar system bodies. Put
simply, there is no clear guidance on what to do if and
when non-intelligent ET life is found, despite the fact
that a discovery could occur at any time and will
undoubtedly prompt immediate need for response from
multiple levels—scientifically, governmentally and
societally. Science and technology are clearly ahead of
policies in a number of areas [e.g. environmental, health
and safety policies (EHS), as well as planetary protection
(PP)], resulting in potentially serious gaps in knowing
what will or should be done upon discovery.
Page 9
Managing the Communications
scenarios.
We already know that communicating about an ET
discovery is likely to be complicated by public attitudes,
misperceptions, Hollywood style science fiction,
ethical/theological considerations, and national interests.
The communication process is likely to be frenetic, with
input from the scientific and space communities as well
as an array of international institutions [11]. This means
that planning for communication about a discovery must
consider how to deal with potential conflicts, gaps,
misunderstandings and debates from the start, whether
they center around scientific topics or otherwise.
Looking
ahead,
the
management
of
communications for a discovery may also depend on
which type of ET life is found first. It is not totally clear
whether the discovery of one particular type of ET life
would enhance or adversely impact other search efforts
underway or planned. For example, if ET life were
discovered by a rover on Mars or in a containment glovebox on Earth, what might be the impact on plans for
future sample return or human missions? What controls
and policies would apply? Could a verified SETI signal
somehow affect ongoing exobiological research? Who
among scientific, theological or governmental institutions
should be involved in making decisions for humankind
about the advisability of further contact or interactions
with ET life and how would we know whether planned
actions could be mitigated or reversed if necessary?
Prominent among the anticipated concerns are
likely to be varied questions of theological and ethical
implications [11], risks to Earth’s biota and environment,
and concerns over the long term advisability and
implications of continued exploration and interaction. To
the extent the humans are directly involved in a
discovery (e.g., handling or collecting samples, analyzing
alien life in labs etc.), serious questions arise about
laboratory worker and/or astronaut safety [12,13].
Additional concerns include the rights of ET life and
responsibilities toward it [14,18], extraterrestrial property
rights and environmental ethics [15,16], and future
actions by either governments or the private sector with
the potential for large scale or global impacts (e.g.,
colonization, commercialization, extractive industries,
tourism, terraforming, etc.) [17,18]. Since all policies,
laws, and ethics on Earth are based upon life as we know
it, some have even suggested the need for a
comprehensive overhaul from a cosmocentric perspective
if ET life is discovered [16,19].
We know there will be tremendous excitement
upon discovery of ET life—and a great opportunity to
educate the public about the science and technology
behind the discovery. As shown in Table 4, all search
types will involve communication about the science and
technology behind a discovery, but additional categories
of scientific and non-scientific information may be
needed to differing degrees for a comprehensive
understanding of the discovery. Consequently, there will
be a need to prepare in advance for handling the diverse
perspectives anticipated.
As preparation for managing the discovery
communication, it may be advisable to plan targeted prediscovery communication efforts aimed specifically at
the scientific and space communities in addition to the
public. Astrobiology is a diverse, multidisciplinary field
in which professionals are likely to focus on a single
discipline or search type, and perhaps not recognize the
diversity of issues, concerns, and implications behind the
various searches. Communications preparations should
ideally involve the education of professional audiences in
order to engage them in systematic analysis and public
discussion about all aspects of the search and discovery
Phys13news / Spring 2011
Citizens worldwide deserve to be informed and
educated about the facts and implications of the first ET
discovery and their meaning in relation to societal
concerns
and
subsequent
actions.
Overall,
communication, outreach and education regarding the
discovery of ET life must be planned with a
multidisciplinary and long-term view—integrating the
scientific,
technological,
societal
aspects
in
information—that will be conveyed to the public,
whether via mass media coverage or through educational
outreach.
The topic of extraterrestrial life is one of keen
interest to diverse publics worldwide. The implications of
discovery and possible future actions by space faring
nations compel us to think about the meaning of life, the
evolutionary trajectory of humankind, and the future of
life on our home planet. How we respond in the short or
long term to the discovery of ET life has significant
repercussions for ourselves and future generations on
planet Earth, as well as for the ET life itself. How we
communicate about it is equally important. As we plan to
communicate about scientific efforts and successes in the
search for life, but it must be done in the context of
responsible exploration for all.
References
[1] NASA Astrobiology Roadmap,
(http://astrobiology.arc.nasa. gov).
[2] United Nations Treaty on principles governing the
activities of states in the exploration and use of outer
space, including the moon and other celestial bodies,
U.N. Doc A /Res /2222(XXI); TIAS #6347, NY,
1967.
[3] J.D. Rummel, Special feature: planetary exploration
in the time of astrobiology: protecting against
biological contamination, in: Proceedings Of The
National Academy Of Sciences (PNAS) 98 (2001)
2128031.
Page 10
[4] M.S. Race, Planetary protection, legal ambiguity and
the decision making process for mars sample return,
Advances in Space Research 18 (1/2) (1996) 345–
350.
[5] S.J. Dick, Life On Other Worlds: The 20th Century
Extraterrestrial Debate, Cambridge U Press, UK,
1998.
[6] J. Billingham, et al., Social implications of the
detection of an extraterrestrial civilization, A Report
Of The Workshops On The Cultural Aspects Of
SETI. SETI Press, SETI Institute, Mountain View,
CA, 1994.
[7] J.E. Tarter, Security consideration in signal detection.
IAC,
IAA-97-IAA
.9.2.05,
International
Astronautical Federation, 3- 5 Rue Mario-Nikis,
75015 Paris, France, 1997.
[8] P. Schenkel, Legal Frameworks For Two Contact
Scenarios, Journal of British Interplanetary Society
50 (1997) 258–262.
[9] S. Shostak, Media reaction to a SETI success, in: IAC
Turin Italy, International Astronautical Federation,
3-5 Rue Mario- Nikis, 75015 Paris, France, 1997.
[10] C. Oliver, et al., The case of EQ Peg: challenge and
Phys13news / Spring 2011
response, in: International Astronautical Congress,
International Astronautical Federation, 3-5 Rue
Mario-Nikis, 75015 Paris, France, 1999.
[11] M.S. Race, R.O. Randolph, The need for operating
guidelines and a decision making framework
applicable to the discovery of non-intelligent
extraterrestrial life, Advances In Space Research 30
(6) (2002) 1583–1591.
[12] J.D. Rummel, et al. (Eds.), A Draft Test Protocol
For Detecting Possible Biohazards In Martian
Samples Returned To Earth, Nasa/CP-2002-211842,
Washington, DC, 2002.
[13] M.S. Race, et al. Planetary protection issues in the
human exploration of mars, in: Invited Paper
Number
ICES
2003-01-2523,
International
Conference On Environmental Systems (ICES,
Vancouver, B.C) 2003, Available Online at
_http://Store.sae.Org/_.
[14] M. Lupisella, The Rights of Martians, Space Policy
13 (2) (1997) 84–94.
[15] E. Hargrove (Ed.), Beyond Spaceship Earth:
Environmental Ethics and The Solar System, Sierra
Club Books, San Francisco, CA, 1986.
Page 11
[16] R. Randolph, et al., Reconsidering The Ethical And
Theological Implications Of Extraterrestrial Life,
Center For Theology And Natural Sciences, Bulletin
17(3), 1–8; _www.ctns.org_.
[17] I. Almár, What could COSPAR do for the protection
of the planetary and space environment? Advances
in Space Research 30 (2002) 1577–1581.
[18] C.P. Mckay, Does mars have rights? An approach to
the environmental ethics of planetary engineering,
in: D. MacNiven, (Ed.), Moral Expertise, Routledge,
NY, pp. 184–197.
[19] M. Lupisella, J. Logsdon, Do we need a
cosmocentric ethic? in: IAC Turin Italy. IAA-97Iaa.9.2.09. International Astronautical Federation, 35 Rue Mario-Nikis, 75015 Paris, France, 1997.
Margaret S. Race is at the SETI Institute in California. She can
be reached at: [email protected]
---------------------------------Young Physicists Corner
The New Biochemistry
by Kathryn Scannell
Last December, a paper published in Science
inspired headlines about the discovery of alien life on
Earth. These headlines were motivated in reference to the
work done by Felisa Wolfe-Simon, of NASA’s
Astrobiology Institute, and her team. The team has
cultured a bacterium capable of growing in an extreme
micro-environment characterised by high arsenic/low
phosphorus concentrations, conditions considered lethal
to typical heterotrophic bacteria. What is so alien about
this?
The biomolecular compositions of all studied
Earthly organisms consist predominantly of 6 essential
elements: carbon, hydrogen, nitrogen, oxygen, sulphur,
and phosphorus. For this reason it became natural to
consider these 6 elements as the building blocks of life.
The incentive behind Wolfe-Simon’s research was to
examine the hypothesis that biomolecular substitution of
one element by another belonging to the same chemical
group, specifically the replacement of phosphorus by
arsenic, is biochemically viable within at least one
particular organism (Wolfe-Simon et al. 2010).The
ability of life on Earth to adapt to stressful environments
by utilizing chemical analogs of essential elements
changes our interpretation of fundamental biochemistry.
The more we learn about how life on Earth persists and
thrives in what we consider extreme environments, the
more we might learn about life everywhere.
Why would arsenic serve as a replacement for
phosphorus? Phosphorus and arsenic are found along the
same column of the periodic table; they have the same
Phys13news / Spring 2011
number of valence electrons, resulting in comparable
chemical behaviour. Interestingly, it is the chemical
similarity to phosphorus that is responsible for arsenic
toxicity in most organisms. More specifically, metabolic
pathways
incorporate
arsenate
(AsO43-)
into
intermediates instead of the usual phosphate (PO43-) due
to an inability to distinguish the two molecules (Rosen
2002). As arsenate is more readily hydrolyzed than
phosphate, any molecule that has integrated arsenate is
subject to a considerably shorter molecular lifespan than
its phosphate counterpart (Baer and Edwards 1981).
Arsenic poisoning in almost every organism results from
them is in corporation of arsenate within biomolecules
along the ubiquitous glycolys is pathway. The less stable
arsenate-intermediates are quickly hydrolyzed, and the
cell does not produce the ATP and NADH usually
obtained through this pathway. The cell is thus deprived
of energy and starves (Champe, Harvey and Ferrier
2005).
Where to find an organism capable of doing this?
To find an organism likely to have the potential to utilize
arsenate rather than phosphate, the team collected
sediments from Mono Lake, California. This lake offers
harsh environmental conditions for microorganisms
living there; it is hypersaline, has a pH of 9.8, and
contains an average arsenic concentration of 200µM
(Wolfe-Simon et al. 2010). This unique circumstance is a
consequence of the closure of this river basin by
surrounding mountains. River water brings solids into
the lake, which are then left behind as the water
evaporates. The sediments collected by the team were
used as the original inoculum, and were placed in an
artificial medium containing glucose, vitamins and trace
metals. There was no addition of phosphate, or of any
supplementary complex organic ingredients. The
researchers added arsenate to the medium incrementally,
increasing the arsenate concentration with each step,
starting from 100µMand eventually reaching 5 mM. By
transferring this to an agar plate, the researchers were
able to select an isolated colony to be moved to the
rartificial media to then be subjected to a range of
arsenate and phosphate concentrations.
GFAJ-1, the particular strain of isolated bacteria,
has been established as a member of the
Halomonadaceae family of Gammaproteobacteria
(Wolfe-Simon et al. 2010). The researchers were able to
demonstrate that in the absence of phosphate, this strain
was able to grow if provided with arsenate. Although the
strain experienced increased proliferation in response to
the addition of phosphate, growth was arrested entirely
when neither phosphate nor arsenate was added. These
findings suggest that, although phosphate may be
preferred, this organism may actually be capable of using
the supplied arsenate in its metabolism.
The researchers determined, through a method
calledinductively coupled plasma mass spectrometry, the
Page 12
intracellular concentrations of both phosphorus and
arsenic in each scenario: their observations are
summarized in Table 1. The ratio of intracellular arsenic
to phosphorus was 7.3 in those organisms provided with
arsenate and not phosphate, compared to a ratio of 0.002
in those cultures provided with phosphate and not
arsenate. It is reasonable to assumethe bacteria were
assimilating the arsenate from the medium.
While this discovery is a very interesting example
of yet another adaptation to extreme conditions by life on
Earth, it is not entirely surprising. Organisms on Earth,
particularly
micro-organisms,
have
developed
adaptations to almost every extreme environment we can
find on the planet. This research is extremely valuable; it
gets people thinking and rethinking about our
characterization of the natural laws we imply exist
through observation and experiment.
(Wolfe-Simon et al. 2010).
To localize it within the cell, the researchers used
radio labeled 73AsO43-. They detected intracellular
arsenic in protein, metabolite, lipid, and nucleic acid cell
fractions (see Table 2), suggesting that GFAJ-1 is indeed
incorporating arsenate into its biochemistry.
The GFAJ-1 strain growing in the arsenate
medium underwent drastic physiological changes. The
cells became swollen, and large vacuole-like regions
were observed. The team propose the vacuoles might
contain poly-β-hydroxybutyrate; this provides the
hydrophobicity that, conceivably, may act to stabilize the
arsenate compounds (Baer and Edwards 1981).
This finding suggests that the building blocks of
life may be more adaptable than we knew to be possible.
An implication of this on the study of astrobiology is an
increase in the range of habitats suited to sustain life
from Earth, encouraging the notion that life may be able
to adapt to seemingly lethal conditions outside of planet
Earth. This research shows us again what remarkable
adaptations billions of years of biological evolution are
capable of generating. This research, however, doesn’t
imply any alien form life with a distinct origin. It would
be very interesting to find a “new type” of life with an
entirely different evolutionary history, unable to be
connected to an accepted phylogenetic tree of life on
Earth in any obvious manner.
References
[1] C. D. Baer, J. O. Edwards, P. H. Rieger, Inorg.
Chem. 20, 905 (1981)
[2] P. C. Champe, R. A. Harvey, D. R. Ferrier.
Biochemistry. USA: Lippincott Williams & Wilkins.
(2005)
[3] F. Wolfe-Simon, J. Switzer Blum, T. R. Kulp, G. W.
Gordon, S. E. Hoeft, J. Pett-Ridge, J. F. Stolz, S. M.
Webb, P. K. Weber, P. C. W. Davies, A. D. Anbar,
Phys13news / Spring 2011
R. S. Oremland. A Bacterium That Can Grow by
Using Arsenic Instead of Phosphorus.Science.
doi:10.1126/science.1197258 (2010)
[4] B. Rosen, FEBS Lett529, 86 (2002).
Kathryn Scannell is a 3rd year undergraduate in the Dept. of Applied Mathematics at the University of Waterloo. She can be reached at: [email protected]
Page 13
CROSSWORD – MOSTLY OPTICAL
by Tony Anderson
Clues →
1: “Nice fern tree” gives optical
hockey infraction (12)
10: Bovine sound (3).
11: Belonging to us (3).
13: Metal (4).
16: Precious stone (3).
17: This snooker ball is white (3).
18: Useful type of diagram in optics
(3).
21: Employment Insurance (abbn) (2).
22: Stimulated light source (5).
23: Home Office (abbn) (2).
24: Low Frequency (abbn) (2).
26: Astronomical source (4).
28: Small insect (4).
29: North East (abbn) (2).
30: “Coop crimes” give this instrument
(10).
34: Faster than a walk (3).
36: Morning (abbn) (2).
38: These rays are really particles (4).
40: Oversize (abbn) (2).
42: Cleaning cloth (3).
43: One of the stooges (3).
44: Artificial Intelligence (abbn) (2).
45: Adjustment control for 25 (down)
(4).
46: Old Testament (abbn) (2).
48: General Electric (abbn) (2).
49: Los Angeles (abbn) (2).
50: Ripped (4).
52: Fish eggs (3).
53: Indian spectroscopist (5).
54: Four stroke engine cycle (4).
55: “Poor Anita Liz” gives this optical
property (12).
Clues ↓
1: May be real or imaginary (5).
2: Negative (2).
3: Preposition (2).
4: Sensitive light detector (3).
5: Caribbean drink (3).
6: Make sharp (5).
7: European Union (abbn) (2).
8: He made rings using 1 (across) (6).
9: Gives light in emergency (6).
12: “Cart on fire” gives beam a
direction change (10).
13: Not dark or heavy (5).
14: “Find fir coat” to bend light (11).
15: Glass refractor (5).
16: Multi-lined device (7).
19: Yachting Association (abbn) (2).
20: May be used to do 6 (down) (4)
25: Shaving or driving aid (6).
27: Rural Route (abbn) (2).
28: Have one of these for a try (2).
31: Picture taker (6).
32: Cereal (3).
33: 22 (across) can do this in lecture
(5).
35: Unemployment Agency (abbn) (2).
37: Chemical tooth? (5).
38: Bundle of 18 (across) gives this
(4).
39: Devour (3).
41: Used to show 14 (down) (4).
47: Also (3).
48: Form of toothpaste (3).
51: Decay (3).
Once you have solved the puzzle, use the letters corresponding to the various symbols in the above grid (in the usual order:
left to right, top row first) to form the names of five famous “optical scientists”:
▲ (10 letters);
‫( ٭‬7);
● (5);
† (5);
♥ (5).
The solution is shown on page 16 of this magazine.
Phys13news / Spring 2011
Page 14
Solution to SIN BIN #137
Fs − m1g = m1a1 = 0
Solution taken from Phil Eastman’s book “A
Decade of SIN”
∴ a1 = 0
Barack Obama is disgruntled with his campaign
manager over recent polls in the US. Not sure what to do
with the manager, Obama comes across a special
punishment device in the basement of the White House
designed by Dick Cheney, that the republicans forgot to
take with them. It consists of placing the subject on a
vertical spring that is resting on an anvil with mass
m2=100Kg. The whole apparatus, (manager m1=50Kg,
plus spring plus block) rests on a support as shown. The
support is then suddenly removed. Find the acceleration
of the manager and the block right after the support is
removed.
∴ Fs + m2 g = m2 aa
( m1 + m2 ) g = m2a2
∴ a2 =
( m1 + m2 ) g
m2
a2 = 1.5g
SIN BIN #138
by Rohan Jayasundera
Free-body diagrams just before the door opens
Two mighty mountain climbers, Anton and
Brenda, standing on two ledges one above the other, are
pulling at two pieces of massless rope, attached to a pack
that weighs 80 N. At Anton’s side, the rope is attached
to two massless springs in series, while at Brenda’s side
it is attached to three massless springs in series. All of
the springs are identical. Brenda pulls down on her rope
with a force of 10 N. Find the force Anton must apply up
on his rope to keep the pack in equilibrium.
1) 30 N
2) 80 N
3) 90 N
4) 110 N
5) 290 N
∑ Fy = Ma y ↓
m1g − Fs = 0
∴ Fs = m1g
Now just an instant after the door is opened, the freebody diagrams are as shown (Note that the FBD for m1
does not change):
Solution to Laureate Transformations #137
1.
2.
Phys13news / Spring 2011
Born → bore → robe → lobe → lone → line →
wine → Wien
Bohr → boor → boot → blot → slot → slit → suit
→ Tsui
Page 15
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Solution for the “Mostly Optical” Crossword
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University of Waterloo Publication Number 40065122
The five “optical scientists” hidden in the above grid are
Fraunhofer, Fresnel, Young, Gabor and Snell.
Phys13news / Spring 2011
Page 16