Graham Warwick/WASHINGTON DC
With launch of the 2001 Mars Odyssey reconnaissance orbiter scheduled for 7 April, NASA believes it has reduced the risk of mission failure as much as possible.
The Odyssey launch is the first in NASA's restructured Mars exploration programme, unveiled last October following the failures of the two previous missions - the Mars Climate Orbiter (MCO) and Mars Polar Lander (MPL).
NASA says the subsequent review of the already planned Odyssey mission not only incorporated fixes recommended by the MCO and MPL failure review boards, but also tried to anticipate and prevent other problems that could jeopardise the mission.
Analyses were conducted to identify and mitigate potential failures in all phases of the mission, NASA says. The MCO was lost during orbital insertion because of one incorrect parameter in the software. To avoid this, mission-critical parameters in the Odyssey software were independently verified.
NASA concluded that the Lockheed Martin-built spacecraft, which is similar to the MCO, is basically sound and most changes resulting from the review affect operation of the Odyssey, says mission manager Dave Spencer.
After its launch by a Boeing Delta II from Cape Canaveral, en route to a Mars arrival on 20 October, thruster calibration firings will be conducted in advance of orbital insertion. Additional navigation data will be available to ground controllers and allowance has been made for a fifth and final trajectory control manoeuvre as little as 7h before orbit insertion.
The capture orbit for the Mars aerobraking procedure has been raised from 226km (140 miles) for the MCO to a "more conservative" 300km, Spencer says.
The Odyssey reconnaissance mission is designed to help identify targets for future Mars lander and rover missions. The orbiter carries instruments to "find evidence of present near-surface water and map mineral deposits from past water activity," says project scientist Dr Steve Saunders.
A gamma ray spectrometer will detect permanent ground ice by measuring hydrogen and other elements in the shallow subsurface of Mars.
A thermal emission imaging system will map the planet at higher resolution than the radar-equipped Mars Global Surveyor (MGS) still in orbit and provide new detail on mineralogy.
The US National Imagery and Mapping Agency believes it has located the $165 million MPL near the Martian south pole after analysing MGS images.Source: Flight International
