The Role of Small Missions in Planetary and Lunar Exploration (1995) / Chapter Skim
Currently Skimming:
1 Background and Current Environment
1 Background and Current Environment
Pages 1-12
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
Missions are few and far between, and failures-when they occur-threaten the entire planetary science program. REPORT MENU Moreover, the budgetary challenges facing our nation mandate that the future NOTICE exploration of the solar system will be increasingly constrained.
|
From page 2... ...
____________________ * General Accounting Office, Space Exploration: Cost, Schedule, and Performance of NASA's Magellan Mission to Venus, NSIAD-88-13OFS, Washington, D.C., May 1988; General Accounting Office, Space Exploration: Cost, Schedule, and Performance of NASA's Mars Observer Mission, NSIAD-88-137FS, Washington, D.C., May 1988; General Accounting Office, Space Exploration: Cost, Schedule, and Performance of NASA's Galileo Mission to Jupiter, NSIAD-88-138FS, May 1988; General Accounting Office, Space Exploration: Cost, Schedule, and Performance of NASA's Ulysses Mission to the Sun, NSIAD-88-129FS, Washington D.C., May 1988; General Accounting Office, Space Science: Causes and Impacts of Cutbacks to NASA's Outer Solar System Exploration Missions, NSIAD-94-24, Washington, D.C., December 1993; General Accounting Office, NASA Program Costs: Space Missions Require Substantially More Funding Than Initially Estimated, NSIAD-93-97, Washington; D.C., December 1992; and Congressional Research Service, Library of Congress, Big Science and Technology Projects: Analysis of 30 Selected U.S.
|
From page 3... ...
The Planetary Observer program of the early 1980s was the most public attempt by NASA to initiate a continuing, small mission planetary line, but it was not approved by the Office of Management and Budget and Congress. Mars Observer, which was to be the first of this series, overran its initial budget by a large factor, for various reasons, including a changing external environment and NASA mismanagement,2,3 and no subsequent Observer missions were flown.
|
From page 4... ...
A primary problem of a planetary program that consists only of large missions is that risk becomes unmanageable. The great cost and importance of any single mission encourage NASA to apply expensive procedures (e.g., redundancy, complex "fail-safe" software, backup spacecraft, superfluous tests, and excessive review)
|
From page 5... ...
. PLANETARY EXPLORER In 1968, the Space Science Board recommended "that NASA initiate now a program of Pioneer/Interplanetary Monitoring Platform-class spinning spacecraft for orbiting Venus and Mars at each opportunity, and for exploratory missions to other targets."4 Subsequent studies conducted by NASA, industrial contractors, and the planetary science community led to the concept of a low cost, spin-stabilized Planetary Explorer spacecraft.
|
From page 6... ...
Unfortunately, what the Space Science Board had envisaged as a low cost program using tried and true instruments and an innovative approach to management, rapidly "crystallized as a single opportunity mission-a Multiprobe and an Orbiter that reflected significant and major advances in the sophistication of spacecraft and their instrumentation.
|
From page 7... ...
Further, the budget available to the project was driven significantly by external factors during the several years in which NASA's space science program was reconstituted in the post-Challenger years. The first Observer mission-the Mars Geoscience/Climatology Orbiter, later renamed Mars Observer-was also the last.
|
From page 8... ...
Political and budgetary complications arising from interactions between human exploration and scientific goals profoundly influenced the Ranger, Surveyor, and Lunar Orbiter programs in the 1960s11 and, more recently, led to the collapse of a proposed series of small lunar science missions. In the 1970s, the preferred way to augment the data gathered by the early lunar robotic probes and by the Apollo missions was to place a satellite equipped with sophisticated remote-sensing instruments into polar orbit about the Moon.
|
From page 9... ...
Following launch on a refurbished Titan 2G intercontinental ballistic missile on January 25, 1994, Clementine was placed into a polar orbit around the Moon a month later. Although it successfully completed three months' worth of lunar measurements, along with many of its technical goals, a software error triggered an uncontrollable spin and Clementine was unable to make the transfer maneuvers necessary to fly past the near-Earth asteroid 1620 Geographos.
|
From page 10... ...
The instrument packages for both Clementine and NEAR are all facility instruments and were preselected, as was the Pathfinder concept, and so none of these missions fully satisfies the mission concept that the committee considers below. NASA has proposed that NEAR and Mars Pathfinder form the start of a new program, the Discovery program, whose stated goals are to "increase flight rates and launch certainty, complement large missions to keep a steady rate of incoming planetary data, broaden university and industry participation in solar system exploration missions, and increase public awareness of solar system exploration missions."15 This proposed program envisages a range of missions and targets.
|
From page 11... ...
9. Space Science Board, National Research Council, Letter report regarding an assessment of the impact on integrated science return from the 1992 Mars Observer mission, from the Committee on Planetary and Lunar Exploration to Geoffrey A
|
From page 12... ...
14. Space Studies Board, National Research Council, Lessons Learned from the Clementine Mission, National Academy Press, Washington, D.C., 1995, in preparation.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.