[Prev][Next][Index][Thread]
No Subject
LEONID MULTI-INSTRUMENT AIRCRAFT CAMPAIGN
Status of project as of Nov. 19, 2001
========================================
2001 LEONID MAC MISSION A SUCCESS
The meteor storm that dazzled observers in Northern America
was studied from an altitude of 40,000 ft by a team of scientists in a
NASA sponsored "Leonid Multi-Instrument Aircraft Campaign". Onboard the
NKC-135 instrumented tanker "FISTA", the researchers trained a wide array
of optical and heat sensors to the rain of meteors. After weeks of intense
preparations under very difficult circumstances by the 418th Flight Test
Squadron and participating researchers, the aircraft departed from Edwards
AFB at 5:45 UT November 18, after a brief potentially mission-grounding
loss of a walky-talky had been resolved. The flight commenced to Alabama,
where the plane turned west on a slow trajectory to cover the anticipated
storm profile. Soon, numerous bright meteors were detected, sometimes 3-4
at a time. On several occasions, the pilots adjusted the heading of the
aircraft to help point the instruments towards sudden persistent luminous
trains. In one instance by turning the aircraft 180 degrees. Close contact
with aircraft operators prevented undue concern from the sudden and irregular
aircraft motions. A spectacular sporadic fireball marked the the end of the
night. Landing occurred around 6:30 am in morning twilight.
It is still too early to know what new data were retreived during the
mission. Researchers will spend much of the next year sorting out the
gigabytes of data. We do know that, for the first time, the mid-infrared
sensor "BASS" was successfully pointed at a persistent train. This will help
clarify the role of dust in explaining the mid-IR emission of trains detected
during the 1999 Leonid MAC mission and perhaps confirm the presence of
surviving organic molecules in the debris. BASS was operated by Dr. Ray
Russell and Dr. David Lynch of the Aerospace Corporation. Several
high-resolution optical spectra were recorded by a CCD spectrograph,
operated by Emily Schaller of Darthmouth College. These data probe the
temperature and physical state in the hottest regions of the
meteor, which determine the survivability of organic molecules. Dr. Rick
Rairden of Lockheed, Palo Alto, reported the detection of
several UV spectra that may help put stronger limits on
the amount of organic breakup products in the meteor plasma. With the help
of the NASA Ames Imaging Technology branch, High-Definition TV spectra were
taken for meteor composition. Finally, slit-spectra of persistent trains were
obtained by Avi Mandell of Penn State University, which may help confirm that
most of the glow is due to emissions from the iron oxyde molecule.
Near real-time flux measurements were reported from aircraft and from two
ground-stations. Both ground sites at Mount Lemmon Observatory, Arizona, and
at Alice Springs, Australia, were hampered by clouds in the beginning of the
night, but cleared micraculously during the peak of the shower. Early results
show that the 1767 and 1699/1866 dust trails dominated Leonid shower activity.
The model by Brown and Cook, favoring the 1799 dust trail, was proven incorrect.
Unlike models by Asher and McNaught and by Lyytinen and Van Flandern,
the peak rates of the 1699/1866 dust trail were not significantly higher
than that of the 1767 dust trail, in agreement with the model by
Jenniskens, that put the 1767 dust trail closer to Earth's orbit. The timing
of the 1767 dust trail was about 20-30 minutes later than predicted and the
peak was broader, which may provide support for recent calculations by Lyytinen
and Van Flandern that showed that several parts of the 1767 dust trail were
bended in shape such as to extend and shift the trail encounter.
Due to the enhanced security measures, foreign nationals were not able
to participate in this year's campaign. In an twist of irony, the chief
scientist and principal investigator, SETI Institute astronomer Dr. Peter
Jenniskens, who is a Dutch National, was also grounded. After providing
support with the preparations in the evening of Nov. 18, he waved his more lucky
colleagues goodby and traveled in the company of Leonid MAC researcher
Ian Murray of Canada to a remote wilderness area north of Edwards AFB.
>From there, they observed the shower amids hundreds of campers and onlookers
that had come out into the hills for the occasion. Rates went up to about
17 meteors/minute, rising to storm levels. A dozen persistent trains
and tens of meteors were filmed by Murray in three passbands. These
results will shed light on the meteor morphology of the 1767 dust trail
ejecta and the early evolution of persistent trains.
-Peter Jenniskens
..........................................................................
Peter Jenniskens
The SETI Institute e-mail: pjenniskens@mail.arc.nasadot gov
NASA Ames Research Center tel: (650) 604-3086
Mail Stop 239-4 fax: (650) 604-1088
Moffett Field, CA 94035-1000
http://leonid.arc.nasadot gov
http://www-space.arc.nasadot gov/~leonid/
http://leonid.arc.nasadot gov/pjenniskens.html
The archive and Web site for our list is at http://www.meteorobs.org
If you are interested in complete links on the upcoming LEONIDS, see:
http://www.meteorobs.org/storms.html
To stop getting email from the 'meteorobs' list, use the Web form at:
http://www.meteorobs.org/subscribe.html