39 countries) as participants in the Challenge, interview data and team estimates of network size indicate that more than 350,000 people participated in some way. Based on the 922 balloon sighting submissions to the DARPA Web site and team interview data, DARPA tracked 58 teams that were able to correctly locate at least two balloons. Following the Challenge, DARPA conducted 53 interviews with team leaders who had competed in the Challenge. These interviews supplemented the quantitative submission-log data collected on the DARPA Web site with qualitative data about participating team strategies, social and technical tools used, network size, mobilization speed, and important social dynamic factors. This data enabled DARPA to reflect on the experience of teams beyond the three in the CSCW session. 4

The Challenge clearly demonstrated the variety, efficiency, and effectiveness of crowdsourcing solutions to a distributed, geo-located, time-urgent problem. The network mobilization time was far faster than expected by DARPA program managers, requiring days instead of weeks. The MIT team constructed a motivated network exceeding 5,000 individuals from four initial nodes in just a few days. Other teams that built around existing networks were able to mobilize them in a day. In one case, a highly connected individual successfully mobilized his contacts through Twitter in less than an hour. As impressive as their use of the network to discover balloons, many teams also used it to do precise, targeted dispatching to verify balloon sightings. Balloon verification, from initial report to confirmation by a targeted dispatch, was typically less than two hours.

While the power of social networks
and the manner in which they are
poised to transform our society have
been gaining attention, the Challenge
revealed several promising means
for using them to mobilize groups of
people for a specific purpose. It also
demonstrated the speed at which so-
cial networks could be used to solve
challenging, national geo-location
problems. This potential has pro-
found implications for a variety of
applications, from natural disaster
response to quickly locating missing
children. However, the Challenge also
demonstrated this wealth of data is
very noisy, reflecting the need for bet-
ter search methods and verification
algorithms.

acknowledgments

We thank the Computer Supported
Cooperative Work 2010 conference
co-chairs Kori Inkpen and Carl Gut-
win for supporting its “Reflecting on
the DARPA Red Balloon Challenge”
session. The MIT team thanks Alex
(Sandy) Pentland, Riley Crane, Anmol
Madan, Wei Pan, and Galen Pickard
from the Human Dynamics Labora-
tory at the MIT Media Lab. The iSchool
team is grateful for the support and
advice provided by John Yen, Da-
vid Hall, Wade Shumaker, Anthony
Maslowski, Gregory Traylor, Gregory
O’Neill, Avner Ahmad, Madian Khab-
sa, Guruprasad Airy, and Leilei Zhu of
Penn State University; Maeve Reilly and
John Unsworth of the University of Illi-
nois; Martin Weiss of the University of
Pittsburgh; Jeffrey Stanton of Syracuse
University; and Gary Marchionini of
the University of North Carolina. We
also acknowledge Ethan Trewhitt and
Elizabeth Whitaker from GTRI for their
participation in the CSCW session.
We also thank Peter Lee and Norman
Whitaker from DARPA and the DARPA
Service Chiefs’ Program Fellows who
conceived and executed the Challenge:
Col. Phillip Reiman (USMC), CDR Rog-
er Plasse (USN), CDR Gus Gutierrez
(USN), MAJ Paul Panozzo (USA), Maj.
Jay Orson (USAF), Timothy McDonald
(NGA), Capt. Derek Filipe (USMC), and
CPT Deborah Chen (USA).

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John C. Tang ( [e-mail]) is a senior researcher in Microsoft research, Mountain View, ca.

Manuel Cebrian ( [e-mail]) is an assistant research scientist in the department of computer science & engineering, university of california at san diego, la Jolla, ca, though at the Massachusetts Institute of technology, cambridge, Ma, at the time of this work.

nicklaus A. Giacobe ( [e-mail]) is a Ph.d. candidate and research associate in the college of Information sciences and technology at the Pennsylvania state university, university Park, Pa.

hyun-Woo Kim ( [e-mail]) is a Ph.d. candidate in the college of Information sciences and technology at the Pennsylvania state university, university Park, Pa.

Taemie Kim ( [e-mail]) is a Ph.d. candidate in the Media laboratory of the Massachusetts Institute of technology, cambridge, Ma. Douglas “Beaker” Wickert ( [e-mail]) is a Major in the u.s. air Force and a program fellow in the transformational convergence technology office of the defense advanced research Projects agency, arlington, Va.

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