the icon, and pull down the menu to select Mars.

Transcription

1 GEOLOGICAL SCIENCES 0050 EXERCISE 4 (12 POINTS): VIEWING MARS FROM ORBIT (AND THE GROUND): BACKGROUND HANDOUT The Exercise is Due Mnday, Octber 28th, 2013 Yu nly need t turn in the exercise prtin. This exercise requires Ggle Earth. Dwnlad instructins and hints were included with the first Ggle Earth exercise. As in earlier exercises, please make sure all yur measurements and answers are in the metric system (kilmeters, meters, r centimeters) [If elevatins are nt shwing up as metric, lk under Tls-Optins-3D View]. There are ccasinally specific instructins regarding which layers shuld be turned n and ff with each questin. Fllwing the instructins will make this exercise easier. Yu will need the file exercise4.kmz, which was sent t yu via and is als available n the class website. All f the questins using Ggle Mars require lking at Mars. T d this, use the icn, and pull dwn the menu t select Mars. Backgrund Here we give brief descriptins f the mst useful layers f the Mars Primary Database may help yu navigate the planet: Featured Satellite Images: This layer shws the lcatin f particular images r bservatins. The range icns are frm a camera called CTX, the cntext imager n the Mars Recnnaissance Orbiter (MRO). If yu click n mst f these range icns, there is an ptin t lad this image, which will allws yu t lk at the full reslutin image in Ggle Earth. The red icns are frm the HiRISE camera. Many f these HiRISE images are already laded int Ggle Earth if the Visible Imagery Layer is n (which is the default, but see Glbal Maps, belw). If yu zm in n these HiRISE images, it might take a secnd t lad the image at reasnable reslutin. This shuld nt be surprising since the camera has ~30 cm per pixel reslutin, which is capable f seeing a remarkable amunt f detail n the surface, including landers, rvers, and Martians (if they are there). Many HiRISE images are anntated, s if yu click n the icn and then the link fr See this image s bservatin infrmatin page, it will ften tell yu smething abut the image. The blue icns are anntated MRO CRISM images; CRISM takes bservatins f Mars at many wavelengths f light frm the visible t the infrared part f the electrmagnetic spectrum, which prvides infrmatin abut the minerals expsed at the surface. Place Names: This layer shws named features Glbal Maps: The Glbal Maps layer has six datasets. If yu have it turned ff, it defaults t Visible imagery. Visible Imagery. This is a msaic f bservatins f Mars at wavelengths clse t what we wuld see with the human eye. Observatins frm HiRISE are als bservable in this layer (high reslutin data that cver a small ftprint). Clrized Terrain. This is the tpgraphy f Mars measured by the MOLA instrument that was nbard the Mars Glbal Surveyr spacecraft. MOLA wrked by shting a laser at the surface frm rbit and timing hw lng it takes fr the light t return t the spacecraft (called laser altimetry ). The elevatins reprted at the bttm f Ggle Earth are mstly frm this tpgraphic data.

2 2 Daytime Infrared. This layer shws the thermal emissin (a prxy fr the surface temperature) measured by the THEMIS instrument nbard the Mars Odyssey spacecraft. This can be a very valuable dataset fr discerning gelgy because slpes that are mre directly illuminated by the Sun are warmer (brighter), and thse that are shadwed r less illuminated areas are cler (darker). This tends t highlight the surface mrphlgy. Hwever, there smetimes are als temperature differences between different regins that are a functin f surface thermal prperties, particularly hw fast the materials warms up ( thermal inertia ). (The slid black areas are image gaps where the THEMIS data in Ggle Earth has nt been updated). Nighttime Infrared. This layer is akin t the daytime infrared layer, except it is bservatins f thermal emissin at night. At night, slar illuminatin is bviusly nt imprtant (!), s nighttime thermal emissin is a functin f hw fast the surface cls ff, which depends mstly n its thermal inertia. Areas that are bright in this dataset are warmer at night, meaning that they have higher thermal inertia (typically this means rckier r mre like bedrck). Viking Clr Imagery and MDIM2.1 Image Map. These are relatively ld, mderate reslutin visible image prducts frm the Viking Orbiter. The Clr Imagery msaic gives an excellent sense f dusty (brighter r higher albed) parts f Mars and less dusty (darker r lwer albed) parts f Mars, but it is at a lw-reslutin, s details are difficult t discern. The MDIM2.1 msaic prvides mre detail f the surface but has been largely supplanted by the ther Visible image datasets. This can be used when the bject f interest is hard t see in the Visible Imagery r Daytime infrared layers. Spacecraft Imagery: Six layers that shw ftprints frm varius instruments. Clicking n the icns gives weblinks t the full reslutin prducts n external websites. Mars Gallery: The Live frm Mars layers shws the recent rbit paths f Mars Odyssey and MRO. If yu turn ne f these layers n, expand it, and duble click Fly Alng, yu can get a sense f the actual spacecraft paths fr particular rbiters. Guided Turs has anntated turs f Mars that might help yu answer the exercise questins. [hint: Fr the Intr t Mars tur, make sure that yu have all ther layers turned ff except Tur Resurces. Fr the Nye tur, turn n the Rver and Landers layer fr the full experience]. Histric Maps has a few hand-drawn, histric maps f Mars frm telescpic bservatins f the Red Planet. Nte that sme f these appear upside-dwn because reflectr telescpes flip the image in their ptics as they send the planet nt the bserver s eye. Rvers and Landers has lcatins, mdels, and traverses assciated with the rvers and landers. Many camera msaics are als available; if yu click n the camera icn, there is a fly int this high reslutin image link. Nte that the waypint infrmatin is nw ut-fdate. A Traveler s Guide T Mars: A layer with anntatins abut certain features frm a bk by Bill Hartmann, a pineering planetary gelgist.

3 1 GEOLOGICAL SCIENCES 0050 I am aware f the Brwn University Hnr Cde [see the Student Handbk, which can be accessed thrugh the Ge0050 web site], understand that this exercise falls under that cde, and knw the penalties that exist fr vilating the cde. Signature: Name: Banner ID#: EXERCISE 4 (12 POINTS): VIEWING MARS FROM ORBIT (AND THE GROUND) Due Mnday, Octber 28, 2013 I. Seeing Mars frm the rbital perspective: Fr an intrductin t Mars, see Explring the Planets, Chapter 6, The 8-minute Guided Tur Intrductin t Mars may als be helpful (see backgrund fr hints n what layers t turn n)). Turn n the Clrized Terrain layer under glbal map. G t the Parana Regin placemark by dubleclicking n that layer in exercise4.kmz. This is in a regin 480 km east f the failed Sviet Mars 6 lander. Lk arund at the Parana regin. Then lk at the area marked by the Arsia Mns Aprn placemark. These placemarks are at the same eye elevatin s yu are seeing each at the same scale. Make sure yu zm in and lk arund t get a sense f the landscape. 1. [1 Pint] After lking at the Arsia Mns aprn and the Parana regin, which has mre superpsed craters? Based n this bservatin, which is lder? 2. [2 Pints] There have been different prcesses imprtant fr mdifying the surface at these tw lcatins. Fill in the fllwing table, nting whether a particular prcess has been a majr gelgic prcess, minr gelgic prcess, r a gelgic prcess that did nt ccur (DNO). It may be helpful t switch t the Visible Imagery layer, r t lad individual images in the Featured Satellite Image layer by turning that layer n, clicking n available icns, and selecting lad this image. Lcatin Arsia Aprn Vlcanic Flws n the Surface Vlcanic Sinuus Rilles Gelgic Prcess Fluvial Valleys and Surface Ersin Impact Cratering Parana Regin

4 2 3. [4 Pints] Nw, pick yur wn regin f interest n the surface t lk at. It is best t start with the Visible Imagery Layer turned n. Yu can use a featured satellite image if yu want t pick smewhere interesting; HiRISE (red icns) are cmmnly amng the best places t start. Using the different available datasets, make the bservatins that allw yu t fill ut the fllwing table (make sure yu zm in t eye elevatins f < ~100 km t see details): What lcatin did yu chse? (Use the Place Name Layer and als write dwn the lat and ln frm the bttm f the screen) What majr characteristics r features d yu bserve in the lcatin yu chse? What gelgical prcess(es) d yu think were particularly imprtant fr frming the characteristics yu bserve? Nw, examine different glbal map layers t see what different datasets say abut the area yu picked. What additinal bservatins can yu make frm this data? Recent years have seen a number f successful landings n the surface f Mars. Turn n the Visible Imagery layer. Open up the Rvers and Landers tab under the Mars Gallery layer and turn n and duble-click n the Mars Phenix lander. The 8-minute Guided Tur by Bill Nye called Mars Explratin may als be helpful as backgrund fr this questin. 5. [2 Pints] Water ice has als been discvered buried within r beneath thin layers f sil far frm the current plar ice caps. Mars Phenix was sent t the nrth arctic circle f Mars t find and explre this buried ice. Examine the Full Circle clr panrama made by Phenix by clicking n the camera icn and selecting Fly int this high-reslutin pht. What evidence d yu see fr water ice in the subsurface at the Phenix landing site? [It might help t quickly sketch the evidence that yu bserve].

5 3 The nrth and suth plar caps are the mst imprtant surface reservirs f water ice n the planet; the suthern cap als has a small, perennial CO 2 ice depsit. 5. (a) [1 pt] Lk at the nrthern and suthern plar caps f Mars in Ggle Earth (the Viking Clr layer has ne f the best views); yu can use the placemarks t navigate, if yu wish. Which plar cap is larger (based n the extent f bright, expsed water ice)? (b) [2 pts] Recently, ESA (the Eurpean Space Agency) and NASA have sent detectrs called MARSIS and SHARAD t Mars that can prvide imaging radar thrugh the water ice layers f the plar caps (which are mre transparent t radar in these wavelengths than rck is). An example f hw the Nrth plar cap lks in its interir with the SHARAD radar instrument is shwn belw and in Ggle Earth. Ntice hw that internal layering in the ice is generally flat-lying, except where it is draped ver preexisting tpgraphy (which has been crudely marked with pink arrws). Figure mdified frm Phillips et al., Using the SHARAD prfile abve and its assciated scale bar (upper right), measure a typical thickness f the nrth plar cap (this is easier t d n the exercise than in Ggle Earth). The nearlypure ice plar depsits in the nrthern hemisphere have a surface area f apprximately 8.1 x 10 5 km 2. Given the thickness that yu can estimate frm the radar prfile, what is the ttal vlume f water ice in the plar cap, in km 3? If this ice were smehw melted, hw wuld the resulting vlume f water cmpare t the ttal vlume f water in the Earth s ceans (~1.4 x 10 9 km 3 )? [Water ice is slightly less dense than just liquid water, but fr the purpses f this questin yu can treat the equivalent vlume f ice and water as equal. Als, keep in mind that Earth is a cnsiderably bigger planet than Mars as yu think abut these numbers (e.g., the surface Area f Mars = x surface area f Earth). If there was an early martian cean, ther surces f water might have existed].