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Home , Chondrite, Desert Fireball Network, Mason Gully (meteorite)

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CATCHING A FALLING (OR ) – FIREBALL CAMERA NETWORKS IN THE 21st CENTURY

Philip A. Bland1, Gretchen K. Benedix2, and the (DFN) Team3

Have you ever seen a shooting star? Have you the precise pre- for these ever seen a fi reball? They are the spectacular rocks (Bland et al. 2009; Towner et al. 2011). fi ery result when space dust and rocks enter our Bunburra Rockhole was an especially inter- atmosphere. Meteors (also known as shooting esting fi nd—a unique basaltic with ) are specks of dust that leave a trail of an Aten-type near- object (Bland et light as they burn up in the atmosphere. al. 2009). This achievement has allowed us to Fireballs are caused by larger bits of material, upgrade and expand the DFN. making them signifi cantly brighter, and can Currently, DFN has 32 camera stations cov- last several seconds in duration. Fireballs and 2 meteors hit the atmosphere at velocities of tens ering ~1.3 million km . The cameras are fully of kilometres per second. Friction from the autonomous systems, capable of operating for air heats the surface of the rock, and 12 months without maintenance and storing ablating it, giving the impression of a ball of all images collected over that period. Each fi re. A meteorite is the surviving material from station incorporates a 36-megapixel full- a fi reball. give planetary scientists format digital and low-light video camera run information about the origin and evolution by an embedded computer. The package is an intelligent imaging system, which calibrates of the : from how the fi rst solids Fireball over Perenjori, 260 km north of FIGURE 1 formed all the way through to the Perth (Western ). The camera its own optics, modifi es observations based of . Meteorites provide a scientifi cally was set up on Perenjori Primary School as part of the on cloud conditions, automatically recognizes Fireballs in the Sky outreach program. priceless record, but their impact is reduced fi reball events, and pre-processes the data prior because we have no spatial context to interpret to uploading it to the project server. The data their compositional data. Imagine trying to orbit) bridges the gap between meteorite and pipeline includes image processing to deter- understand the geology of a continent if all you research, with the potential to revolu- mine fi reball position at sub-pixel level, trian- had to work with was a collection of random tionize both fi elds. Although the methodology gulation and fi reball trajectory modelling, and rocks dumped in your yard. That is where we employed in these earlier networks is sound, dark fl ight trajectory modifi ed by weather and are with meteorites. We know meteorites come they are limited by their location: temperate forecast climate modelling. The fi nal facility from space, mostly from the . We zones where vegetation and weather condi- will incorporate 70 stations extending over can pinpoint their precise origin in the Solar tions are not well suited for meteorite preser- twice the present area to record meteorite falls, System by determining the orbit that they were vation or retrieval. It is hard to spot a meteorite track re-entry of space debris, and determine on before they hit our atmosphere. However, in a cornfi eld, on the tundra, or in a forest. landing sites for each. this is only possible if we are able to track the Moreover, meteorites weather away quite rap- fi reball before it lands. Combining the orbit idly on Earth (Bland et al. 1998); even brief Citizen Science with the recovered meteorite is a major step exposure to rain will affect the primordial DFN is a natural outlet for community out- towards interpreting the record of early Solar record they hold (Jenniskens et al. 2012). reach/engagement because of the widespread System processes that meteorites contain. interest in fi reballs and meteorites. Fireballs The Desert Fireball Network get more and more media coverage, espe- Camera Networks Deserts are exceptionally suited to fi nding cially in the age of expanding use of dash- Fireball camera networks are designed to meteorites due to the lack of plant cover and board and security cameras. Fireballs in the recover meteorites with orbits. The fi rst net- because the environmental conditions limit Sky (FITS) is a citizen science project linked work, based in the Czech Republic, became degradation (Bland et al. 2000). Around 80% to the DFN (www.fireballsinthesky.com. active in 1959 and continues to operate as part of all meteorites have been found in deserts. au) with the goal of sharing the research of the European Fireball Network (Oberst et Could a network sited in a desert deliver and involving the global public. School stu- al. 1998). In the 60s, 70s, and 80s, two other greater numbers of meteorites with orbits? dents and the general public are encouraged networks were operational in North America, The benefi t is that searching should be easier. to contribute and interact with scientists as covering parts of the US (Prairie Meteorite The major diffi culty is building hardware the program develops, essentially becoming Network; McCrosky et al. 1978) and Canada to survive and operate autonomously for members of Fireballs in the Sky community. (Meteorite Observation and Recovery Project; extended periods in a harsh environment. To There are a number of ways to engage with the Halliday et al. 1996). Despite covering over test the concept, a trial network of four fi lm team: e-newsletters, a blog, Facebook (www. a million square kilometers of the Earth’s cameras in the Nullarbor desert of Western facebook.com/fi reballsinthesky), and Twitter surface, only a handful of m eteorites have Australia was established in 2007 (Bland et (@fi reballssky). A smartphone app (www.fi re- been recovered. This is unfortunate because al. 2012). Australia was considered ideally ballsinthesky.com.au/download-app) has been the promise of these camera networks is suited for the network because of clear skies developed so that the public can record and very great—knowing the spatial context (an and arid environmental conditions. Prior to share their fi reball sightings with scientists, this project, there were no known southern participating in real-time research (FIG. 2). hemisphere meteorites with orbits, or indeed The app works around the world, allowing any extended campaigns observing southern orbital data to be confi rmed from anywhere on the , even if no meteorite is found. 1 Curtin University, Department of Applied Geology, hemisphere fi reballs (FIG. 1). The initial Desert Perth, WA, Australia Fireball Network (DFN) covered only a small Users receive updates on the specifi c event that E-mail: [email protected] area (172,000 km2), but by 2010, two mete- they witnessed. A recent upgrade adds details on meteor showers throughout the and 2 E-mail: [email protected] orites had already been recovered (Bunburra Rockhole and ) using trajectory provides users a display directing them to the 3 DFN Team members: Martin Towner, Jonathan specifi c location in the sky for that shower. Paxman, Martin Cupak, Robert Howie, Eleanor information calculated from fi reball images. Sansom, Jay Ridgewell, Kathryn Dyl, Luke Daly, Lucy The images also allowed us to determine Forman, Hadrien Devillepoix, and Monty Galloway

ELEMENTS 160 JUNE 2015 CosmoELEMENTS

Three screenshots illustrating the main (MIDDLE) To record a sighting, the user points the (RIGHT) Once a user selects a , the app FIGURE 2 features of the Fireballs in the Sky phone at the start and end positions in the sky and will provide data such as expected peak, zenith hourly smartphone app. (LEFT) The menu screen allows a user “draws” the path of the fi reball. The user is then rate, and phase. The app will then direct the to report a sighting, to fi nd current and upcoming prompted to edit the created simulation by adjusting user to the best area to look in the sky, in real time. meteor showers in their area, and get up-to-date news duration, brightness, shape, and colour of the fi reball on what’s happening with the DFN research team. before reaching a summary page. Because it is a simulation, not a video, this is done after the fi reball has burned out. With multiple reports, a sighting can be confi rmed and will be listed on the app for users to check.

Finally, with technologies invented for the next generation digital The goal of DFN is to increase recovery of meteorites with orbits: a observatories, we are developing an inexpensive “kit” fi reball camera growing, lasting resource for the research community. It is our hope station that would allow interested amateurs to plug in a digital camera that with the smartphone app and new home kit hardware, the public and have their own advanced fi reball observatory. A versatile interface can make a real contribution to the fi eld and participate in this research will allow users to customize camera settings, schedule operations, and as it happens. download imagers using Wi-Fi. The ability to use it for daytime pho- tography means that the system can be adapted for multiple functions outside of fi reball observations.

REFERENCES Bland PA, Berry FJ, Pillinger CT (1998) Rapid Bland PA and 13 coauthors (2012) The Australian McCrosky RE, Shao C-Y, Posen A (1978) Prairie in Holbrook: an 57Fe Mössbauer spec- Desert Fireball Network: a new era for planetary Network Fireball Data. I. Summary and orbits. troscopy study. and Planetary Science science. Australian Journal of Earth Science 59: Meteoritika 37: 44-59 33: 127-129 177-187 Oberst J and 8 coauthors (1998) The “European Bland PA, Bevan AWR, Jull AJT (2000) Ancient Halliday I, Griffi n, AA, Blackwell AT (1996). Fireball Network”: current status and future meteorite fi nds and the Earth’s surface environ- Detailed data for 259 fi reballs from the Canadian prospects. Meteoritics and Planetary Science 33: ment. Quaternary Research 53: 131-142 camera network and inferences concerning 49-56 the infl ux of large . Meteoritics and Bland PA and 17 coauthors (2009) An anomalous Planetary Science 31: 185-217 Towner MC and 10 coauthors (2011) Mason Gully: basaltic meteorite from the innermost main belt. the second meteorite recovered by the Desert Science 325: 1525-1527 Jenniskens P and 70 coauthors (2012) Radar Fireball Network. 74th enabled recovery of the Sutter’s Mill meteorite, a Meeting: Abstract #5124 carbonaceous . Science 338: 1583-1587

ELEMENTS 161 JUNE 2015