Why Aren't There Any Public Archives of Exoplanet Observations?
Garrett Hardin published a landmark article in Science
entitled "Tragedy of the Commons" (1968). It used the analogy of
farmers who could graze their sheep in a community's pasture, called a
"commons." Each farmer was free to add sheep to his flock, and there
was more benefit than loss for an individual farmer to do so. But as
other farmers did the same the commons was over-grazed, and soon it was
unrecoverable. Only then did all the flocks die of starvation. In
retrospect, each farmer 's decision could be justified as contributing
to his income, in the short-term. The only way to avoid such a tragedy
is for the farmers to come together before the commons is over-grazed
and decide on rules limiting what each could do. Too often this
realization is acknowledged after it's too late.
So, what does this lesson have to do with a "public archive" of
exoplanet observations. The relevance is actually the flip side of the
tragedy of the commons. Consider the following story. Suppose there are
several professional teams observing exoplanet transits that are known
(i.e., coordinates and ephemeris are in the public domain). Suppose
each team has multiple observations of 6 transiting exoplanets. One of
these teams has 43 such observations, and other teams have similar
numbers. Each team is faced with the question of what to do with their
archive of known transiting exoplanets. There's no secret about the
exoplanet's location, or the approximate transit depth, or length, or
transit schedule. What's to keep each team from presenting this archive
to a common archive? Before such a decision can be made it is prudent
for each team to review its archive for each exoplanet and search for
anomalous patterns. The patterns could be mid-transit timings that come
early for awhile, then shift to coming late, etc (due to another
exoplanet in a resonant orbit). Or the transit depth and length could
be changing in a secular manner (due to precession in an elliptical
orbit). Or the OOT data could show slight fades at preiodic intervals
(due to another exoplanet in the same system). Each group's data set
for a given exoplanet, by itself, is probably inadequate for detecting
any of these interesting patterns. Only if all data sets are combined
in a "commons" can a good search for these effects be made. But suppose
a commons were somehow created? Who will be the first to add their
data? If one group adds their data they won't be privy to anyone else's
data; yet each of the other groups that are still holding their data
will now have the benefit of combining their secret data with the newly
contributed "commons" archive. This gives an advantage to all the teams
that "hold out." If one of the holdout teams discovers a pattern,
leading to suspicion of a new exoplanet discovery for example, they
will quickly publish without the need for including in their
co-authorship list those who contributed their data to the commons.
After all, that data is in the public domain. This is a
situation of "no good deed goes unpunished; no bad deed goes
unrewarded." The first to publish get kudos from their sponsor, and the
suckers who contributed their data to the commons are losers.
Remember the lesson of Hardin's Tragedy of the Commons. Only if
participants get together and work out rules of behavior will tragedy
be avoided. One form this could take for the exoplanet situation is for
the sponsors (NASA, NSF) to force the professional teams to cooperate,
with a warning that "those who drag their feet will lose their
funding." I've had enough experience with NASA HQ program managers
before retiring to know that this is unlikely to happen, and I have to
bite my tongue to say nothing more about why.
Is the situation hopeless? No. We're amateurs, and we are not
motivated by funding! In fact, many of us are not motivated about
getting credit for things, and the boost it could have on our
"standing" within a community. We are free to create our own "commons
archive"! This is what I'm proposing, and my call for cooperation is to
amateurs everywhere. Let the pro's hoard their precious exoplanet
transit observations. We'll just have to do a good job of creating
quality light curves. Whereas I'm privy to 72 LC observations that I
will not divulge, because that's a promise I made before joining a
pro/am exoplanet team, we amateurs can create our own archive with
comparable coverage if we cooperate among ourselves.
This is a "call to arms" for observing and sharing. It's also an
experiment, and it may not fly. My preference is to convince AAVSO to
undertake the creation of the archive. I have offered to help them set
it up. They are currently accepting text files of exoplanet transits,
but it's difficult to determine where that data is going. We need to
have it properly "processed" - with each observation file being
converted to something useful, similar to the light curve example shown
above.
Hardin, Garrett, 1968, Science, 162:1243-1248.
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WebMaster: Bruce L. Gary This site opened: August
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