Fire in the Sky: Community Science with a Network of AllSky Cameras

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Fire in the SkyCommunity Science with a Network
of All-Sky Cameras

• Frank Sanders
• DMNH DES Associate
• 15 October 2001

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OUTLINE
1) Introduction Solar System Billiards
2) Collisions with Earth and Computation of Orbits
3) How the Community Reacts When Fireballs Occur
4) Meteor Showers
5) What DMNH Historically Does When Fireballs
Occur
6) What DMNH Has Not Been Able to do Historically
7) More Recent DMNH Fireball Efforts
8) What the Museum Will Do with the All-Sky
Network
9) What Students Can Do with the All-Sky Network
10) Example Case History (off-line, time
permitting)
Community Science with a Network of All-Sky
Cameras Frank Sanders
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Introduction Solar System Billiards

• Overall solar system
• Asteroid belt
• JUPITER Solar Systems Heavyweight
• How things get thrown toward Earth
• Geometry of Earth encounters
• How we can determine original orbits

Community Science with a Network of All-Sky
Cameras Frank Sanders
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Solar System Small Bodies The Oort Cloud
Billions of icy-dusty blocks orbiting our sun at
distances approaching halfway to the nearest
star. They are left over from the original
proto-solar system cloud. They have changed
little in 4.6 billion years.
Orbits sometimes disturbed by nearby stars
Once disturbed, each body may either gain energy
and be ejected from solar orbit or else may lose
energy and drop into the inner solar system
From Beatty Chaikin, The New Solar
System Cambridge Press 1998
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Comets that are injected into the inner solar
system are further perturbed by Jupiter...
sometimes into orbits that intersect Earths
path in space. They, or debris derived from them,
may strike Earth under this circumstance.
Comet Hale-Bopp by Frank Sanders
Community Science with a Network of Sky Cameras -
Frank Sanders
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Solar System Small Bodies Comets
Some asteroids and smaller meteoroids are
probably derived from the cores of dead comets.
.and they sometimes collide with Earth, too.
From Beatty Chaikin, The New Solar
System Cambridge Press 1998
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Solar System Small BodiesThe Asteroid Belt
So material in this region remained in the
proto-planetary stage, never accreting into a
planet-size mass
Gap between Mars and Jupiter Why no planet here?
?
?
?
Gravity effects of the proto-Jupiter probably
stopped planetary accretion here.
?
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Solar System Small BodiesAsteroid Families
About 318 Earth masses
Asteroids are material that failed to form a
planet, mainly due to Jupiter gravity effects
Materials have been minimally altered for past
4.6 billion years
The Belt occupies critical zone where more
volatile stuff appears
These are orbital, not mineralogical, families
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Solar System Small Bodies Kirkwood Gaps
Resonances (gaps) at
41 72 31 52 73 21 53
Kirkwood Gaps are gravity resonances with Jupiter
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Solar System Small Bodies Belt Collisions
Any given body may orbit in the asteroid belt
with high stability for millions of years. But
over geological periods of time..
Debris are then swept out by Jupiter, sometimes
onto Earth-crossing orbits
Collisions do occur, and the resulting debris may
have new orbits that pass through the Kirkwood
Gaps.
From Beatty Chaikin, The New Solar System
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Earth Crossing Orbits
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Earth Crossing Orbit
Detail
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Earth Crossing Orbits
Usually Dont Intersect Earths Orbit (!)
Pictures often make them appear to intersect
Earths orbit because they are 3-D entities that
we usually draw in 2 dimensions
From Beatty Chaikin, The New Solar
System Cambridge Press 1998
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies But When They DO
Intersect.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Significance
Small bodies are minimally altered since the
formation of the solar system. Studying them
tells us about the solar systems origins. We
should collect as much of this material as
possible for scientific purposes.
In contrast to small bodies, the planets have, to
a greater or lesser extent, all generated
substantial alteration of their component
materials, and thus only provide us with limited
information about their origins.
From Beatty Chaikin, The New Solar
System Cambridge Press 1998
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Who Cares?
Collecting meteorites gives us a virtually
no-cost sample-return mission.
But to make the effort most useful, we also need
to know where the original body was orbiting.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Up-Close View of an
Encounter
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Encounter Geometry
Basics
If meteoroid encountered Earths gravity but not
its atmosphere or surface, it would swing through
on a hyperbolic path.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Solar System Small Bodies Encounter Details
Community Science with a Network of Sky
Cameras--Frank Sanders
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Encounter Details Tracing an Orbit Backward
Forward
IF we can obtain date, time, descent
angle, direction (azimuth) of arrival,
and entry speed (scalar of velocity vector) of a
meteoroid, then we can compute both.
A probable fall location for meteorite(s)
and an original orbit, telling us where the
the thing originated in our solar system
Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits
Only a few people in the world have ever computed
meteoroid orbits. A.D. Dubyago (1940s-60s) of
Kazak State University, Peter Brown at Los
Alamos National Laboratory, and Zdenek Ceplecha
in the Czech Republic are only people I know who
have or are doing this.
F. Sanders has developed this capability for the
Museum, and has checked his results against
computations by Peter Brown for three meteors
Tagish Lake, Elbert, and La Garita. Results have
agreed to within fractions of a degree.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Procedure
Basic Procedure
1) Gather raw data from witnesses and/or cameras
2) Determine descent angle, azimuth of arrival,
and sub-point of retardation (this gives the
apparent radiant)
3) Compute astronomical variables for that moment
in time (solar longitude, longitude of the apex,
GST, LST, Julian date, etc.)
4) Compute right ascension (RA) and declination
(dec) of the apparent radiant
5) Compute the local zenith angle correction for
Earth gravity, and also the so-called diurnal
aberration correction (small)
Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Procedure continued
Basic Procedure, continued
6)Compute corrected radiant RA and dec, incl.
step 4 corrections.
7) Transform corrected radiant to true radiant
(heliocentric frame of reference, in ecliptic
coordinates)
8) Use heliocentric velocity and ecliptic
coordinates of the true radiant, along with
earlier computed astronomical variables to obtain
orbital elements (eccentricity, inclination to
ecliptic, semi-major axis, longitude of the
ascending node, longitude of perihelion, etc.)
Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Software
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Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Software 2
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Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Software 3
.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Computing Orbits Software 4
.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Summary of the Science
So now we see the big picture of whats going on
1) Jupiter throws asteroids, meteoroids, comets
and cometary cores at us. Sometimes they run into
Earths atmosphere and then some chunks may
survive to reach Earths surface.
2) These objects represent minimally altered
material from the birth of the solar system. We
should collect them for study, and also should
determine where they came from, if possible.
3) To accomplish either of these two goals, we
need to know entry details (numbers!). This is
where Community Science sky cameras and
eyewitnesses come into the picture.
Community Science with a Network of All-Sky
Cameras Frank Sanders
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What Happens When a Meteoroid Enters the
Atmosphere Physical Effects
Body enters at more than 25,000 mph (40,000
km/hr).
Plasma ball forms around it at more than 5000
degrees Kelvin. This is a FIREBALL, more
accurately BOLIDE.
Object lights up with a brilliance that can
illuminate the ground like daylight at distances
exceeding 20 miles.
Witnesses see the object at distances in excess
of 100 miles (and they all think it was a mile
away!).
Object experiences forces of 100-300 gs and
usually begins to break up at about 15-25 miles
altitude.
Pieces slow down above 40,000 feet and fall to
Earth.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What Happens When a Meteoroid Enters the
Atmosphere Physical Effects, continued
Shock waves (both bow shock and explosive) occur.
Sound is heard at distances of tens of miles, and
U.S. Government nuclear sensors may detect at
100s of miles.
Some witnesses hear sound simultaneous with
visual phenomenon. Electrophonic sound is not
understood.
Break-up, usually at about 10-15 miles altitude,
is often spectacular. This is retardation.
Subsequent to break-up, many small embers may be
seen to fall toward surface by nearby witnesses.
Pieces that fall to Earth are meteorites.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What Happens When a Meteoroid Enters the
Atmosphere likely Meteorite Falls
Small meteoroids burn up completely at high
altitudes.
Large meteoroids burn (ablate) material, too. But
they have enough mass to survive into the lower
atmosphere.
The large mass plowing into the lower atmosphere
at high speed generates the plasma ball, becoming
a fireball.
Thus,the occurrence of a fireball is a good (but
not certain) indication that a meteorite has
fallen to Earth. Sadly, most are not recoverable.
Tracking fireballs is equivalent to tracking
possible meteorite falls.
Community Science with a Network of Sky
Cameras--Frank Sanders
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How the Community Reacts
Point of retardation
Simulated fireball track in the sky
Community Science with a Network of Sky
Cameras--Frank Sanders
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How the Community Reacts
Witnesses are typically flabbergasted.
They are anxious to share their experience with
someone.
They are anxious to know more about what they saw
and where it came from.
Hundreds or thousands of telephone and E-mail
reports flood into the Museum.
Painting by a witness to a fireball
Community Science with a Network of Sky
Cameras--Frank Sanders
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How the Community Reacts Media
Mass media (print, radio, television) are anxious
to obtain timely and accurate information on what
has happened.
Interest occurs at both local and national level.
Large number of media inquiries typically flood
into the Museum. People want timely information
and images, if available.
Community Science with a Network of Sky
Cameras--Frank Sanders
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More Community Interest Meteor Showers
The old tails of comets (mainly dust grains)
orbit the sun indefinitely. Earth periodically
passes through some of these debris clouds.
These debris clouds generate meteor showers when
Earth passes through each cloud on a yearly basis.
Result is predictable meteor showers. Observation
of such showers interests the public and can help
us verify sky camera performance.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum has done Historically about
Fireballs
Community Science with a Network of All-Sky
Cameras Frank Sanders
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What the Museum has done When Fireballs have
Occurred
Led by Jack Murphy (with Andy Caldwell, Al
Keimig, etc.)
1) Obtain telephone reports
2) Follow up telephone reports with on-the-spot
eyewitness interviews
3) Reduce eyewitness interviews to probable
flight paths, manually
4) Place notes in archival files
5) In exceptional cases, try to localize fall
location and conduct some ground search
Fireball flash at 20 miles slant range, November
1995
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum has not been able to do when
fireballs have occurred
Fast data collection and analysis have not been
possible, due to reliance on hit-or-miss of
eyewitness reports.
Have not been able to respond to media requests
for information in less than several weeks, for
the same reason.
Have not generally been able to provide any
imagery of fireballs.
Have not been able to obtain any data on entry
speed, critical to determination of both fall
location and orbit.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum has developed recently for
fireball responses
Beginning in 1997, Frank Sanders conceived of a
Colorado-wide sky camera system to provide
1) Quantitative data on speed and location, for
computing 3-dimensional flight tracks via
overlapping coverage
2) Raw data for computing orbits and fall
locations
3) Obtaining fireball imagery to satisfy the
public and media need for pictures.
Goals were to involve Community in collecting
data, and to feed information back to the public
quickly and accurately.
Sanders built a prototype sky camera and
demonstrated it in 1997, but support for a
program not deemed possible at that time.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum has developed recently for
fireball responses, cont.
But recently, the Museum has developed a
Community Science program that will use sky
cameras deployed across Colorado. (More on that
later.)
Sandia National Laboratory in Albuquerque
coincidentally has been building its own network
in New Mexico, and is partnering with the Museum
to share data and expertise.
Software has been developed to compute
3-dimensional flight tracks from eyewitness and
camera data
Other software has been developed and tested to
compute orbits from camera data.
Sanders and Chris Peterson have further developed
sky camera designs
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum has developed recently for
fireball responses, cont.
Gianna Sullivan leads the Community Science
Program. She is developing a wide range of
capabilities, discussed later. Andy Caldwell and
Chris Peterson are part of that team.
Meanwhile, much emphasis has also been placed on
gathering eyewitness data and analyzing reports
quickly, for media feed-back.
Electronic reports are now taken via E-mail in
addition to the telephone, which makes for faster
and easier filing and analysis of data
Substantial emphasis has been placed on
responding to media requests for information.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum will do with a Network of
All-Sky Cameras
Community Science with a Network of All-Sky
Cameras Frank Sanders
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What the Museum will do with a Network of All-Sky
Cameras
Two Major Components
1) Continuously monitor Colorado skies for
fireballs and meteors
2) Involve students in the project, maintaining
sites, acquiring data, and sharing data out to
other students and the Museum.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum will do with a Network of All-Sky
Cameras Overlapping Coverage
1) Cameras are placed on school rooftops at
separation distances of, typically, 50-80 miles
2) Cameras monitor sky 24 hrs/day, with software
set up to force recording when meteor events
occur
3) Recorded data are transmitted to the Museum
and to students at other schools
4) Overlapping camera coverage allows us to
determine flight tracks, fall locations, and
original solar orbits.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Compute Original Orbit
What the Museum will do with a Network of All-Sky
Cameras Overlapping Coverage
Station 1
Flightline computed
Station 2
Point of Retardation
Compute fall location
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum will do with a Network of All-Sky
Cameras, cont.
Even if data are obtained from a single camera,
the flightline can be computed by combining
camera data and eyewitness reports
BUT the camera data will provide velocity, and
thus allow us to compute at least approximate
orbital data.
In addition to scientific outputs, Museum will be
able to RAPIDLY respond to media requests for
information.
Fast-response approximation of flight path
Fast-response images of fireballs for video media
Fast-response indications of fall locations and
orbits for media
Community Science with a Network of Sky
Cameras--Frank Sanders
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What the Museum will do with a Network of All-Sky
Cameras, cont.
And Journal Papers, as well, to share information
with the scientific community.
Community Science with a Network of Sky
Cameras--Frank Sanders
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What Students will do with a Network of All-Sky
Cameras
Community Science with a Network of All-Sky
Cameras Frank Sanders
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What Students will do with a Network of All-Sky
Cameras
Students operate hardware and software to acquire
data
Students store data from fireball and meteor
events
Students evaluate and analyze data from the
events
Students share data with other schools and the
Museum
Students are motivated to further study
Related mathematics
Related physics
Solar system origins and related astronomy
Community Science with a Network of Sky
Cameras--Frank Sanders
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Conclusions
Community Science All-Sky Camera Project will
provide
1) Opportunity for Colorado students to
participate in a meaningful way in scientific
observations, data collection, and data analysis,
and data sharing.
2) Critical data for the Museum to use in an
ongoing scientific project to study meteors and
meteorites
3) Vastly improved ability to provide timely and
accurate data to the public following fireball
events.
Community Science with a Network of Sky
Cameras--Frank Sanders
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Off-line demonstration of flightline computation
software and orbit computation software
Software written in Labview by Frank Sanders, 2000
Community Science with a Network of Sky
Cameras--Frank Sanders