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<p class="MsoNormal"><span lang="FR">Dear Aura Science Community,<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Many of you may have heard that NASA Headquarters is planning to terminate the three Earth Observing System (EOS) flagship missions, Terra, Aqua, and Aura, late in the summer of 2023. In the last few weeks, Headquarters has begun notifying
the science and applications communities so that they have time to migrate to datasets from other instruments.
<i>More importantly, this notification signals that these communities now have the opportunity to voice their opinions as to why the EOS missions should continue.
</i>If budget were not an issue, the Aura Mission would last two additional years, likely terminating in late summer 2025 when solar power generation will become insufficient.
<o:p></o:p></p>
<p class="MsoNormal"><i><u><o:p><span style="text-decoration:none"> </span></o:p></u></i></p>
<p class="MsoNormal"><i><u>Headquarters’ Justification for Decommissioning<o:p></o:p></u></i></p>
<p class="MsoNormal">Headquarters’ primary reason for ending the EOS missions prematurely is simply budgetary. There will be a substantial budget shortfall beginning in the 2024 which is important as NASA’s next generation of Earth science missions, known collectively
as the <a href="https://science.nasa.gov/earth-science/earth-system-observatory">
Earth System Observatory</a> (ESO) missions, will begin moving into the costly design and fabrication phases. Delays for the ESO missions would be required to continue operations of Terra, Aqua, and Aura beyond 2023 as EOS mission operations is not a trivial
expense. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Another reason for ending the EOS missions early is because the satellites are all currently drifting. However, for Aura, this drift from its mean local time (MLT) crossing is minimal: ~0 mins currently; ~15 min by mid-2024; ~45 min by
mid-2025. Both the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) teams assure that the science and trend quality of their data products will remain undiminished to the end.<o:p></o:p></p>
<p class="MsoNormal"><i><u><o:p><span style="text-decoration:none"> </span></o:p></u></i></p>
<p class="MsoNormal"><i><u>Current Aura Satellite and Instrument Status<o:p></o:p></u></i></p>
<p class="MsoNormal">All Aura satellite systems are nominal and are predicted to remain so until mid-2025. The instruments are aging gracefully.<o:p></o:p></p>
<p class="MsoNormal"><i><o:p> </o:p></i></p>
<p class="MsoNormal"><i>MLS:</i> Currently there are no follow-on missions planned to continue most of the MLS products, many of which are integral to middle atmospheric research. The importance of MLS has been underscored by its unique ability to capture the
unprecedented increase in stratospheric humidity following the Hunga Tonga-Hunga Ha'apai underwater volcanic eruption in January of this year. Given that this once-in-a-century (or rarer?) moistening is expected to linger for years, premature loss of the
daily near-global MLS measurements of stratospheric water vapor would be particularly regrettable.<o:p></o:p></p>
<p class="MsoNormal"><i><o:p> </o:p></i></p>
<p class="MsoNormal"><i>OMI:</i> There are currently several follow-on instruments that have similar capabilities as OMI. Nevertheless, OMI’s long-term, stable hyperspectral solar irradiance data record is highly valued by the solar community and its criteria
pollutant trace gas records (e.g., NO<sub>2</sub>, SO<sub>2</sub>, ozone) have proven particularly useful for assessing the impacts of emissions regulations and pandemic lockdowns on air pollution around the world.
<o:p></o:p></p>
<p class="MsoNormal"><i><u><o:p><span style="text-decoration:none"> </span></o:p></u></i></p>
<p class="MsoNormal"><i><u>A Swell of Community Support – Two More Years!<o:p></o:p></u></i></p>
<p class="MsoNormal">The Aura MLS and OMI instruments have supported the scientific research and applications communities with stable, high-quality data for almost 18 years. With your voices, we raise the possibility of continuing Aura for
<i>an additional two years</i>. We encourage you to provide your written justification directly to Bryan Duncan (<a href="mailto:bryan.n.duncan@nasa.gov">bryan.n.duncan@nasa.gov</a>) and Ken Jucks (<a href="mailto:kenneth.w.jucks@nasa.gov">kenneth.w.jucks@nasa.gov</a>),
who will forward it to the appropriate Headquarters’ personnel. A swell of support from the science and applications communities will provide Headquarters with the necessary justification to approach Congress for additional resources to continue the EOS Terra,
Aqua and Aura Missions. As another option, you may also voice your support to your favorite Congressperson.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">If you have any questions or comments, please feel free to contact us.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you in advance for your support.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sincerely,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Bryan Duncan (Aura Project Scientist)<o:p></o:p></p>
<p class="MsoNormal">Ken Jucks (Aura Program Scientist)<o:p></o:p></p>
<p class="MsoNormal">Nick Krotkov (Aura Deputy Project Scientist)<o:p></o:p></p>
<p class="MsoNormal">Nathaniel Livesey (MLS PI)<o:p></o:p></p>
<p class="MsoNormal">Joanna Joiner (US OMI science team leader)<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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