1. Atmospheric Measurements
2005: IVA-1B
2010: 1A
Priority: High
(2005 Version)
1B. Investigation. Determine the atmospheric fluid variations from ground to >90 km that affect EDL and TAO including both ambient conditions and dust storms.
Measurements:
- Measure velocity (v), pressure (P), temperature (T) and density (ρ) in the upper, middle and lower atmosphere during EDL. Obtain as many profiles at various times and locations as possible (requested for all landed missions). Sample rate should be high enough (~100 Hz) to quantify turbulent layers. Specific direct or derived measurements would include:
- Density from 120 km to surface ranging from high altitude values of 10-9 to near-surface values of 10-1 kg/m3, dr = 1% of local ambient
- Pressure from 120 km to surface ranging from high altitude values of 10-7 to near-surface values of 15 mb, dP= 1% of local ambient
- Temperature 60-300 K, dT = 0.5K
- Directional Wind Velocity, 1-50 m/sec, dv = 1 m/s
Particular emphasis on measurements between 0-20 km to quantify boundary layer wind and turbulence and 30-60 km where vehicle dynamic pressure is largest.
- Monitor surface/near-surface velocity (v(z)), pressure (P), temperature (T(z)), and density (r) as a function of time. Quantify the nature of the surface heating driver and associated boundary layer turbulence at altitudes above station. Data defines the initial conditions for high altitude modeling. Obtain data from as many locations as possible (requested for all landed missions). Surface/near surface packages should measure directly:
- Pressure, at surface, 0.005 mb to 15 mb, dP = 2 microbar, full diurnal sampling, rate= >10 Hz
- Velocity, at surface, 0.05-50 m/sec, dv = 0.05 m/s, horizontal and vertical, full diurnal sampling, rate= 10 Hz
- Air temperature, at surface, 150-300 K, dt = 0.04K, full diurnal sampling, rate= 10 Hz
- Ground temperature 150-300 K, dt = 1K, full diurnal sampling, rate= 1 Hz
- Air temperature profile, 0-5km, <1km resolution, 150-300K, dt=2K, full diurnal sampling, rate=1 Hz
- Velocity profile, 0-5km, <1km resolution, 1-50 m/sec, dv=1 ms/, horizontal and vertical, full diurnal sampling, rate=1 Hz
- Opacity, visible, depth 0.2-10, dtau = 0.1, once every 10 min
- Make long-term (>> 1 Martian year) remote sensing observations of the weather (atmospheric state and variations) from orbit, including a direct or derived measurement of:
- Aeolian, cloud, and fog event frequency, size, distribution as a function of time.
- Vertical temperature profiles from 0-120 km with better than 1 km resolution between 0-20 km, 1-3 km resolution between 20-60 km, 3 km resolution > 60 km and with global coverage over the course of a sol, all local times[Development work required for T from surface to 20 km].
- Vertical density/pressure profiles from 0-120 km with better than 1 km resolution between 0-20 km, 1-3 km resolution between 20-60 km, 3 km resolution > 60 km and with global coverage over the course of a sol, all local times[Development work required for r from surface to 20 km].
3-D winds as a function of altitude, from 0-60 km with better than 1 km resolution below 20 km, and 1-3 km resolution between 20-60 km, and with global coverage over the course of a sol, all local times [Development work required at all altitudes for an independent means to derive V, with special emphasis from surface to 20 km].
Note particular emphasis on measurements between 0-20 km to quantify boundary layer wind and turbulence and 30-60 km where vehicle dynamic pressure is large.
- At time of human EDL and TAO, deploy ascent/descent probes into atmosphere to measure pressure, temperature and velocity just prior to human descent at scales listed in 1Ba.
Note #6: We have not reached agreement on the minimum number of atmospheric measurements described above, but it would be prudent to instrument all Mars atmospheric flight missions to extract required vehicle design and environment information. Our current understanding of the atmosphere comes primarily from orbital measurements, a small number of surface meteorology stations and a few entry profiles. Each landed mission to Mars has the potential to gather data that would significantly improve our models of the Martian atmosphere and its variability. It is thus desired that each opportunity be used to its fullest potential to gather atmospheric data. Reconstructing atmospheric dynamics from tracking data is useful but insufficient. Properly instrumenting entry vehicles would berequired.
Source:
MEPAG (2008), Mars Scientific Goals, Objectives, Investigations, and Priorities: 2008,
J.R. Johnson, ed., 37 p. white paper posted September, 2008 by the Mars Exploration Program Analysis Group (MEPAG) at http://mepag.jpl.nasa.gov/reports/index.html.
