Total Ozone Mapping Spectrometer

Image:Toms-2004-09-06-FULLDAY GLOB.PNG

The Total Ozone Mapping Spectrometer (TOMS) was a NASA satellite instrument, specifically a spectrometer, for measuring the ozone layer. Of the five TOMS instruments which were built, four entered successful orbit. The satellites carrying TOMS instruments were:

• Nimbus 7; launched October 24, 1978. Operated until 1 August 1994. Carried TOMS instrument number 1.
• Meteor-3-5; launched 15 August 1991. Operated until December 1994. Was the first and last Soviet satellite to carry a USA made instrument. Carried TOMS instrument number 2.
• ADEOS I; launched 17 August 1996. Operated until 30 June 1997. Mission was cut short by a spacecraft failure.
• TOMS-Earth Probe; launched on July 2, 1996. Operated until 2 December 2006. Carried TOMS instrument number 3.
• QuikTOMS; launched 21 September 2001. Suffered launch failure and did not enter orbit.

Nimbus 7 and Meteor-3-5 provided global measurements of total column ozone on a daily basis and together provided a complete data set of daily ozone from November 1978 to December 1994. After an eighteen-month period when the program had no on-orbit capability, TOMS-Earth Probe launched on 2 July 1996, followed by {{nowrap|ADEOS I}}. ADEOS I was launched on August 17, 1996, and the TOMS-instrument onboard provided data until the satellite which housed it lost power on June 30, 1997.

TOMS-Earth Probe (Total Ozone Mapping Spectrometer - Earth Probe, TOMS-EP, originally just TOMS, COSPAR 1996-037A){{Cite web|url=https://space.skyrocket.de/doc_sdat/toms-ep.htm|title = Toms-Ep}} was launched on July 2, 1996, from Vandenberg AFB by a Pegasus XL rocket. The satellite project was originally known as TOMS, back in 1989 when it was selected as a SMEX mission in the Explorer program. However, it found no funding as an Explorer mission and transferred to NASA's Earth Probe program, getting funding and becoming TOMS-EP. The small, 295 kg satellite was built for NASA by TRW; the single instrument was the TOMS 3 spectrometer. The satellite had a two-year planned life. TOMS-EP suffered a two-year delay to its launch due to launch failures of the first two Pegasus XL rockets. The launch delays led to alternations in the mission; the satellite was placed in a lower than originally planned orbit to achieve higher resolution and to enable more thorough study of UV-absorbing aerosols in the troposphere. The lower orbit was meant to complement measurements from ADEOS I enabling TOMS-EP to provide supplemental measurements. After ADEOS I failed in orbit, TOMS-EP was boosted to a higher orbit to replace ADEOS I. The transmitter for TOMS-Earth Probe failed on December 2, 2006.{{cite web |url=http://toms.gsfc.nasa.gov/news/news.html#mar05 |title=News |series=Total Ozone Mapping Spectrometer |publisher=NASA |date=March 5, 2007 |url-status=dead |archiveurl=https://web.archive.org/web/20120829044403/http://toms.gsfc.nasa.gov/news/news.html#mar05 |archivedate=August 29, 2012}}

The only total failure in the series was QuikTOMS, which was launched on September 21, 2001, on a Taurus rocket from Vandenberg AFB, but did not achieve orbit.{{cite web |url=https://www.gsfc.nasa.gov/topstory/20010705quiktoms.html |title=QuikTOMS Mission |publisher=NASA |date=July 10, 2001 |url-status=dead |archiveurl=https://web.archive.org/web/20010821121343/https://www.gsfc.nasa.gov/topstory/20010705quiktoms.html |archivedate=August 21, 2001}}

Since January 1, 2006, data from the Aura Ozone Monitoring Instrument (OMI) has replaced data from TOMS-Earth Probe.{{cite web |url=http://jwocky.gsfc.nasa.gov/ |title=TOMS turns the mapping job over to OMI |series=Total Ozone Mapping Spectrometer |publisher=NASA |date=January 9, 2006 |url-status=dead |archiveurl=https://web.archive.org/web/20060127090141/http://jwocky.gsfc.nasa.gov/ |archivedate=January 27, 2006}} The Ozone Mapping and Profiler Suite on Suomi NPP and NOAA-20 have further continued the data record.