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Fire in the Sky: Community Science with a Network of All-Sky Cameras. Frank Sanders DMNH DES Associate 15 October 2001. 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.

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fire in the sky community science with a network of all sky cameras

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

Frank Sanders

DMNH DES Associate

15 October 2001

outline
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

introduction solar system billiards
Introduction: Solar System Billiards
  • Overall solar system
  • Asteroid belt
  • JUPITER: Solar System’s 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

slide4

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

slide5

Comets that are injected into the inner solar system are further perturbed by Jupiter...

…sometimes into orbits that intersect Earth’s 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

slide6

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

slide7

Solar System Small Bodies:The 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….

?

slide8

Solar System Small Bodies:Asteroid 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

slide9

Solar System Small Bodies: Kirkwood Gaps

Resonances (gaps) at:

4:1 7:2 3:1 5:2 7:3 2:1 5:3

Kirkwood

Gaps are

gravity

resonances

with

Jupiter

slide10

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

slide11

Solar System Small Bodies:

Earth Crossing Orbits

Community Science with a Network of Sky Cameras--Frank Sanders

slide12

Solar System Small Bodies:

Earth Crossing Orbit Detail

Community Science with a Network of Sky Cameras--Frank Sanders

slide13

Solar System Small Bodies:

Earth Crossing Orbits Usually Don’t Intersect Earth’s Orbit (!)

Pictures often make them appear to intersect Earth’s 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

slide14

Solar System Small Bodies:

But When They DO Intersect….

Community Science with a Network of Sky Cameras--Frank Sanders

slide15

Solar System Small Bodies: Significance

Small bodies are minimally altered since the formation of the solar system. Studying them tells us about the solar system’s 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

slide16

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

slide17

Solar System Small Bodies:

Up-Close View of an Encounter

Community Science with a Network of Sky Cameras--Frank Sanders

slide18

Solar System Small Bodies:

Encounter Geometry Basics

If meteoroid encountered Earth’s 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

slide19

Solar System Small Bodies: Encounter Details

Community Science with a Network of Sky Cameras--Frank Sanders

slide20

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

slide21

Computing Orbits

Only a few people in the world have ever computed meteoroid orbits.

A.D. Dubyago (1940’s-60’s) 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

slide22

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 localzenith angle correctionfor Earth gravity, and also the so-called diurnal aberration correction (small)

Community Science with a Network of Sky Cameras--Frank Sanders

slide23

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

slide24

Computing Orbits: Software

.

Community Science with a Network of Sky Cameras--Frank Sanders

slide25

Computing Orbits: Software 2

.

Community Science with a Network of Sky Cameras--Frank Sanders

slide26

Computing Orbits: Software 3

.

Community Science with a Network of Sky Cameras--Frank Sanders

slide27

Computing Orbits: Software 4

.

Community Science with a Network of Sky Cameras--Frank Sanders

summary of the science
Summary of the Science

So now we see the big picture of what’s going on:

1) Jupiter throws asteroids, meteoroids, comets and cometary cores at us. Sometimes they run into Earth’s atmosphere and then some chunks may survive to reach Earth’s surface.

2) These objects represent minimallyaltered 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

slide29

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 g’s 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

slide30

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 100’s 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

slide31

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

slide32

How the Community Reacts

Point of retardation

Simulated fireball track in the sky

Community Science with a Network of Sky Cameras--Frank Sanders

slide33

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

slide34

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

slide35

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

what the museum has done historically about fireballs
What the Museum has done Historically about Fireballs

Community Science with a Network of All-Sky Cameras: Frank Sanders

slide37

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

slide38

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

slide39

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

slide40

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

slide41

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 reportsare 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

what the museum will do with a network of all sky cameras
What the Museum will do with a Network of All-Sky Cameras

Community Science with a Network of All-Sky Cameras: Frank Sanders

slide43

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 studentsin 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

slide44

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

slide45

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

slide46

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

slide47

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

what students will do with a network of all sky cameras
What Students will do with a Network of All-Sky Cameras

Community Science with a Network of All-Sky Cameras: Frank Sanders

slide49

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

slide50

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

slide51

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