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Date Entered: 6 September 1989
Date Last Revised: 22 March 1991
The landing site lies on the smooth Hesperian plains near a Noachian mountain block east of Hadriaca Patera. Hadriaca is a Mid-Hesperian central vent volcano northeast of Hellas Planitia, with radial ridges, a low profile and a smooth floored caldera at its center. Dao Vallis, an apparent outflow channel, drops 5 km in elevation as it descends across the southwestern flank of Hadriaca to its terminus in Hellas Planitia. At least 6 different types of terrain units are found either in Dao Vallis or within several hundred kilometers of it.
Scientific Rationale
Area contains six types of terrain units, volcanics, channel material, basin material, mountainous terrain, plains material. Potential to detect water vapor. Possible frosts, clouds, and dust storms in Hellas Planitia.
Objectives
An overall survey (incl. closeup images and infrared mapping) of Noachian mountainous terrain, Hadriaca Patera caldera and slope, Hesperian Plains, Dao Vallis, and Hellas Planitia. Detection of water vapor.
Terrain Units:
AHh - Hadriaca Patera Formation: Floor material of central caldera and of surrounding volcanic eruption material.
Ah5 - Channeled Plains Rim Unit: On east rim of Hellas Planitia basin.
Hch - Older Channel Material: Floors of Dao and Harmakhis Valles.
Hpl3 - Smooth Hesperian Plains: Flat, relatively featureless plains in southern material.
Nh1 - Basin-Rim Unit: Material of Hellas Planitia basin rim.
Nm - Noachian Mountainous Material: Large, very rugged, isolated blocks scattered around Hellas Planitia Basin.
TENTATIVE TRAVERSE ROUTE:
1. Balloon Exploration Vehicle is to be landed on the smooth Hesperian plains region at about 31 deg. S, 263 deg. W. The balloon vehicle will release a surface payload, possibly a rover/soil sample collector, while at this initial landing site.
2. When the wind direction is suitable, the balloon vehicle will take off for flight in a generally southwest direction. After obtaining as many images of the nearby Noachian mountain block (Nm) as possible, the balloon vehicle will then study the Hesperian plains (Hpl3) below it. After this, there will be several possibilities for the next terrain unit to be studied, depending on the exact direction that the wind carries the balloon.
3. The Hadriaca Patera formation (AHh); the eruption material on its eastern and southern slopes, and possibly even the central caldera.
4. The sources of the eastern and central branches of Dao Vallis; the floor(s) of these channels (Hch) could then be studied for evidence of water vapor, haze, frosts, and dust. If the balloon flies over these channels, it can observe the Hesperian plains material (Hpl3) situated between these two branches of the upper Dao Vallis.
5. Further flight towards the southwest will probably bring the balloon over the channeled plains unit (Ah5) terrain, which adjoins Hellas Planitia.
6. After sunset, the balloon's gas will cool, the vehicle will lose lift and have to land. This will give the opportunity for direct study and sampling of the martian surface by the balloon vehicle payload at night.
7. If the balloon vehicle operates successfully for several days, it will have a good chance of reaching Hellas Planitia's modified eolian, fluvial, and lava flow material (Hh3). The balloon vehicle can then investigate dust storms, clouds, frost, and water vapor in at least part of Hellas Planitia.
If possible, departures from this general flight plan should be made for a closer (and possibly even a surface landing) investigation of interesting features as they are spotted on the images produced by this proposed balloon survey and traverse.
In addition to a television imaging system, the balloon vehicle payload should at least contain an infrared mapping spectrometer for the detection of water vapor and a radar or laser altimeter to determine height above the martian surface.
Potential Problems
Suitable wind direction to keep the balloon flying in a general southwesterly direction. Dust storms, haze, and clouds. Extreme wind velocities. Dust, rubble, and lava on the martian surface.
Trafficability
To be determined; see Potential Problems above.
Estimated Traverse Distance
300 km to over 1,000 km for the Balloon Exploration Vehicle. Up to 300 km for the lander rover(s).
Other
Some desired characteristics of the balloon are:
a) It can fly at heights from a few meters to over a kilometer above the martian surface; and
b) it can land payloads (preferably mobile) at interesting sites it picks out on the Martian surface.
The balloon might operate (at least partially) in a joint traverse with a more advanced Mars Rover/Sample Return mission on the surface.
This mission can also be flown in tandem with the Balloon Site Exploration Vehicle for Site 032 - Dao Vallis. If the Site 032 mission fails completely of falls far short of complete success, the balloon vehicle described here can be retargeted for the Site 032 mission to land initially in the upper end of the western branch of Dao Vallis; otherwise, the somewhat more abmitious balloon exploration that has been described here will be attempted.
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