Spectra of the cellular photospheric flows are determined from full-disk Doppler velocity observations acquired by the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) spacecraft. Three different analysis methods are used to separately determine spectral coefficients representing the poloidal flows, the toroidal flows, and the radial flows. The amplitudes of these spectral coefficients are constrained by simulated data analyzed with the same procedures as the HMI data. We find that the total velocity spectrum rises smoothly to a peak at a wavenumber of about 120 (wavelength of about 35 Mm), which is typical of supergranules. The spectrum levels off out to wavenumbers of about 400, and then rises again to a peak at a wavenumber of about 3500 (wavelength of about 1200 km), which is typical of granules. The velocity spectrum is dominated by the poloidal flow component (horizontal flows with divergence but no curl) at wavenumbers above 30. The toroidal flow component (horizontal flows with curl but no divergence) dominates at wavenumbers less than 30. The radial flow velocity is only about 3% of the total flow velocity at the lowest wavenumbers, but increases in strength to become about 50% at wavenumbers near 4000. The spectrum compares well with the spectrum of giant cell flows at the lowest wavenumbers and with the spectrum of granulation from a 3D radiative-hydrodynamic simulation at the highest wavenumbers.

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<p>The origins of the martian moons Phobos and Deimos remain enigmatic. Over the past decades a range of spacecraft have observed Phobos and Deimos in order to constrain their origin and evolutionary history, with proposals for their origins ranging from captured asteroids, to coalesced material from a giant impact on Mars. However, given the orbits these spacecraft and the orbits of Phobos and Deimos, Phobos has garnered the majority of the attention. Now thanks to the unique orbit of the Emirates Mars Mission (EMM) Hope spacecraft and a minor correction to its nominal science orbit, EMM has a unique opportunity to examine Deimos in great detail while fully retaining the originally designed mission to capture the variability in the martian atmosphere and exosphere.</p> <p>Following a minor orbital adjustment maneuver campaign beginning in August 2022, EMM will encounter Deimos multiple times, progressively observing the martian moon at lower and lower distances beginning in early 2023. These flybys culminate in the closest approach of ~150 km, observing the mostly illuminated, far side of Deimos. All three EMM instruments, the Emirates eXploration Imager (EXI), the Emirates Mars Infrared Spectrometer (EMIRS), and the Emirates Ultraviolet Spectrometer (EMUS) have observation sequences tailored to these flybys, collecting the highest resolution multispectral visible imaging data, thermal infrared surface temperatures and emission spectra, and ultraviolet spectra.  When combined these instrument observations will provide key insights into the composition, morphology, and surface physical properties of the least studied martian moon, Deimos.</p>

<p>The Emirates Mars Mission (EMM) Hope probe launched on 20 Jul 2020 and entered Mars orbit on 9 Feb 2021, carrying a payload of 3 complementary instruments to characterize the global atmosphere across the full range of altitudes (surface to exosphere) at diurnal and seasonal timescales.  The unique, high-altitude orbit of the Hope probe (19,970 km periapse, 42,650 km apoapse altitude, 25 deg inclination, 54.5-hour period) that enables its synoptic view of the red planet also brings the spacecraft across the orbit of Mars’ outermost moon, Deimos.  The Hope trajectory was slightly modified by two maneuvers in Aug 2022 and Jan 2023 that will allow the surface of Deimos to be observed in a series of flybys in Feb-Mar 2023.  Here we present preliminary results from the Emirates Mars Ultraviolet Spectrometer (EMUS), an imaging spectrograph with a wavelength range of 100-170 nm and a field of view of 10.75 x 0.18 deg (using the high-resolution slit position).  We will derive the absolute reflectance of the surface, search for any compositionally distinct spectral features (e.g. carbon, polycyclic aromatic hydrocarbons, water ice), and examine any spatial heterogeneity across the surface.</p>