ESTIMACIÓN ECONOMÉTRICA DE LOS INGRESOS DE LAS

G e o m etric ally re-re g isterin g p ix els w ith in M ID R data was u sed to artific ially introduce parallax in order to create synthetic stereo im age data. T he degree the p ix els are sh ifted w ith in the M ID R d ata (eith er to the left or rig h t) is p ro p o rtio n al to th eir co rresp o n d in g altim etric data. The g reater the to p o g rap h ic height, the greater the geom etric m ovem ent o f the pix el w ithin the im age data, and hence the g reater artificial p arallax produced. M agellan altim etry d ata gaps w ere filled using PV O and V enera data. By an e m p iric a l p ro c e ss, tw o e x ag g e ra tio n s w ere fo u n d to be m o st a p p ro p ria te , lOx and 50x ex ag g eratio n . No one ex ag g e ra tio n is ap p ro p riate fo r all areas o f Venus. H ow ever, 50x w orks w ell for sm oother areas such as the plains, and lOx for m ore rugged areas.

1 . 5 Implications of the New Magellan Data

W hat are the im plications o f such an extensive data set? As p re v io u s ly m e n tio n e d , M a g e lla n h as p ro v id e d n e a r g lo b a l coverage (nearly 98% ) o f an E arth sized planet. The reso lu tio n o f the data exceeds that o f previous m issions and, in com parison to rem o te sensing im ages o f the E arth, a larg er p ro p o rtio n o f the surface o f V enus is im aged at a greater reso lu tio n . T his allow s n ear global geological in v estig atio n o f the planet. T he data from this m issio n are currently being used to address a m u ltitu d e o f im p o rtan t g eo lo g ical questions.

O f fundam ental im portance for Venus (indeed any planet) is the question regarding the m echanism s o f heat loss. Since V enus h as a p p ro x im a te ly th e sam e siz e, m ean d e n s ity an d b u lk c o m p o sitio n as the E arth, it is co n sid ered th a t it should have sim ilar geological activity as the Earth {Solomon an d Head, 1982, 1991). T hree d istin ct m echanism s are responsible for heat loss on so lid su rface p lan ets: (1) p late tecto n ics, the rec y c lin g o f the lith o sp h ere; (2) ho tsp o t volcanism , the tran sp o rtatio n o f h eat via larg e u p w ellin g m antle plum es; and (3) lith o sp h e ric co n d u ctio n through a globally continuous shell {Morgan a n d Phillips, 1983;

S o l o m o n a n d H e a d , 1982, 1991). On E arth , th e d o m in a n t m echanism o f h eat loss is plate tectonics. H ow ever, h eat loss on V enus is still poorly understood.

T he m echanism o f heat transport on a p lan e t is in tim ately linked to its tectonic and volcanic evolution {Solomon a n d Head,

1991). In ord er to help define and constrain h eat loss processes throughout the evolution o f V enus, it is fundam ental to resolve a num ber o f geological and geophysical issues. T hese issues include: (1 ) th e v e n u s ia n s tra tig ra p h y , in p a r tic u la r a q u a lita tiv e u n d e rs ta n d in g o f v o lca n ic a c tiv ity w ith tim e. In c o n stra in in g g eo lo g ical a ctiv ity , the theory th at V enus m ay hav e u n d erg o n e periods o f catastrophic resurfacing and global tecto n ic events m ay be assessed; and (2) the styles o f volcanism p revalent on V enus in co m p ariso n to E arth. W ith the advantage o f M ag ellan data, this thesis w ill attem pt to contribute to the two points above.