Hope: build a picture of a changing Martian atmosphere

The Emirates Mars Mission, known through its Hope Probe, reached Mars orbit on February 9, 2021. The Mohammed Bin Rashid Space Centre led spacecraft development with international partners, including the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics, Arizona State University and the University of California, Berkeley. The mission combined a national exploration effort with shared engineering and instrument expertise.

Hope’s atmospheric investigation asks how conditions vary across Mars and how different atmospheric regions connect. A single impressive globe image cannot answer that question. Scientists need observations taken at known places and times, repeated across changing conditions. The mission’s sampling strategy is therefore part of its scientific design, just as important as the appearance of the spacecraft or the date of arrival.

The Emirates Exploration Imager, EXI, observes at ultraviolet and visible wavelengths. The Emirates Mars Infrared Spectrometer, EMIRS, uses thermal infrared measurements to investigate properties such as temperature and the distributions of dust, water ice and water vapor in lower atmospheric regions. The Emirates Mars Ultraviolet Spectrometer, EMUS, studies upper-atmosphere emissions relevant to composition and atmospheric escape.

These instruments do not measure the same quantity three times. Connecting their results requires attention to altitude sensitivity, observing geometry and timing. If a dust event is observed in the lower atmosphere and a change later appears at greater altitude, scientists can examine a possible relationship. Coincidence alone does not establish a cause; transport, seasonal behavior and measurement uncertainty must also be considered.

Coverage in a fictional observing plan

Local time — open definition matters because an atmosphere changes during the day as well as across seasons. Observing one region only in the afternoon can hide behavior that occurs elsewhere or at another hour. Hope’s varying views help researchers build a broader picture, but a combined atmospheric map should not be mistaken for an instantaneous measurement of every location at every altitude.

In a fictional observing plan, four latitude bands are each sampled at three local times, giving twelve intended combinations. If three combinations are missing, nine of twelve are covered: 75 percent. That fraction describes coverage of this simplified plan, not measurement accuracy or complete seasonal coverage. These numbers are a teaching example, not Hope mission results. Data products and their accompanying timing, geometry and processing records let researchers decide which comparisons are justified and where additional observations would be valuable.