table of contents
A study indicating that if Mars could somehow acquire an Earth-like atmospheric …
|[ 1 ]|
If we ignore absorption of incoming solar radiation, a fractional increase in g is a simple function of . Taking the present gray opacity on Mars to be nearly zero, Eq. 1 implies that a gray opacity near = 3 should increase the surface temperature to 280 K from the current 210 K. If Mars can acquire an Earth-like atmosphere somehow, the transmission of outgoing radiation at frequencies below 700 cm1 and above 1,400 cm1 will be just a few percentage points as on Earth. We therefore direct our attention to filling the window.
In the interval between 700 and 1,400 cm1, we approximate the spectral transmission of the Earth's atmosphere at a crude resolution (7). We then double the spectral optical thicknesses, because the lower gravity of Mars requires 2.6 times Earth's column airmass to achieve 100 kPa pressure at the surface. Next, we seek to add a mixture of greenhouse gases that will lower the overall transmission through the window to 5% (= e3).
We considered 21 fluorine compounds, some of which were not previously synthesized, observed, or documented. Fluorine in the bulk composition of Mars has been estimated at 32 ppm by mass vs. 19.4 ppm for the Earth (8). Abundances of the other elements are more than sufficient for our purposes. We performed ab initio calculations to find vibrational fundamental frequencies and band intensities. After estimating bandwidth and selecting five of the candidate molecules, we stepped along the window spectrum at intervals of 1 cm1 to calculate spectral transmission and derive gray opacity. Then we iterated with the aim of minimizing the required number of molecules of manufactured gas.
Finally, we will demonstrate that Earth-like ozone and oxygen, if present, would shield all of the selected molecules effectively against rapid photolysis, such that their continuous replenishment by synthesis on Mars then might be feasible.
rating: 5.75 from 4 votes | updated on: 16 May 2007 | views: 7155 |