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The Need for Speed in Near-Earth Asteroid Characterization | | J. L. Galache
; C. L. Beeson
; K. K. McLeod
; M. Elvis
; | | Date: |
3 Apr 2015 | | Abstract: | We have used Minor Planet Center data and tools to explore the discovery
circumstances and properties of the currently known population of over 10,000
NEAs, and to quantify the challenges for follow-up from ground-based
telescopes. The increasing rate of discovery has grown to ~1,000/year as
surveys have become more sensitive, by 1mag every ~7.5 years. However,
discoveries of large (H =< 22) NEAs have remained stable at ~365/year over the
past decade, at which rate the 2005 Congressional mandate to find 90% of 140m
NEAs will not be met before 2030. Meanwhile, characterization is falling
farther behind: Fewer than 10% of NEAs are well characterized in terms of size,
rotation periods, and spectra, and at current rates of follow-up it will take
about a century to determine them even for the known population. Over 60% of
NEAs have an orbital uncertainty parameter, U >= 4, making reacquisition more
than a year following discovery difficult; for H > 22 this fraction is over
90%. We argue that rapid follow-up will be essential to characterize
newly-discovered NEAs. Most new NEAs are found within 0.5mag of peak brightness
and fade quickly, typically by 0.5/3.5/5mag after 1/4/6 weeks. About 80% have
synodic periods of <3 years that bring them close to Earth several times a
decade. However, follow-up observations on subsequent apparitions will be near
impossible for the bulk of new discoveries, as these will be H > 22 NEAs that
tend to return 100 times fainter. We show that for characterization to keep
pace with discovery would require: Visible spectroscopy within days with a
dedicated >2m telescope; long-arc astrometry, used also for phase curves, with
a >4m telescope; and fast-cadence (<min) lightcurves obtained within days with
a >= 4m telescope. For the already-known large (H =< 22) NEAs,
subsequent-apparition spectroscopy, astrometry, and photometry could be done
with 1-2m telescopes. | | Source: | arXiv, 1504.0712 | | Services: | Forum | Review | PDF | Favorites | |
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