If engineers succeed in bypassing the short, the second hurdle will be heating Nozomis main engine for a Dec. 14 braking maneuver that will insert the spacecraft into its planned orbit around Mars, said Ichiro Nakatani, JAXAs Nozomi spacecraft manager.
JAXA officials said the cause of the short circuit appears to have been a large solar flare that hit the spacecraft in April 2002. Nakatani told Space News in a Nov. 21 telephone interview that attempts to bypass the electrical short-circuit were proceeding and that there still was some cause for hope.
We have a probability factor for Nozomi hitting Mars at about or less than one percent if we fail the Dec. 9 maneuver. If we fail to recover from the short circuit then we will be forced to abandon Nozomi and give up on the Mars orbit insertion, and it will lead to a Mars flyby, Nakatani said.
We dont have a probability figure for the chances of repairing the electrical problem, but we are still a little bit optimistic, he said. Nakatani said Nozomis power problem doesnt lie in the electrical power generation system, but in a circuit or circuits feeding from the system. Such circuits are needed to activate the 541 kilogram spacecrafts small thrusters to realign the spacecraft Dec. 9.
Nozomis mission is to take measurements of Mars upper atmosphere using a highly elliptical orbit that will take the spacecraft as low as 150 kilometers above the surface of the planet. If the short circuit is bypassed and the Dec. 9 maneuver completed successfully, the electrical system still needs to work to heat up Nozomis main 500-Newton engine to slow the probe into its designated orbit.
Nakatani said JAXA officials believe the spacecrafts fuel has not solidified, but that the main engine is very, very cold and still needs Nozomis electrical system-powered heaters if it were to fire after 5 months of cooling following its June 2003 swing-by past the Earth.
The events of the next few weeks will decisively determine the fate of Nozomis prolonged mission of five years and five months, a mission that, at the same time, has proved a valuable learning experience for Japan as it considers more missions to other planets, said Matogawa. Originally launched July 4, 1998, Nozomi was supposed to have reached Mars in October 1999. But a glitch with the spacecrafts thrusters during a Dec. 1998 swing past Earth left Nozomi without enough fuel to ease it into a Mars orbit according to the original flight plan.
A new flight plan saw Nozomi slingshot round the Earth in Dec. 2002 and again in June. But the flight plan also exposed Nozomi to the massive solar flare that damaged the spacecrafts electrical systems. Despite all these problems, JAXA has still managed to keep the mission running and perform the two swings past Earth.
Whatever the outcome of the next few critical days, Nozomi has already made a great contribution to our knowledge and ability to conduct interplanetary exploration, said Matogawa.
We have learned about spacecraft design, orbit determination, swing-by techniques and mission management. This will make us stronger for future missions, Matogawa said.
Matogawa also stressed that Nozomis flight plan had factored in internationally-agreed standards for planet protection formulated by the Paris-based Committee on Space Research designed to prevent interplanetary contamination.
We have met the international standards and guidelines for planetary protection and there is less than a one percent chance of a crash. Less than one percent is a very good figure and 894 kilometers orbit is actually optimal, he said.
Matsuura Shigekazu, deputy director of the Ministry of Education, Culture, Sports, Science and Technologys Space Development and Utilization Division said the Japanese government accepts that there is about a one percent chance of Nozomi crashing into Mars. He said Nov. 21 that Japan had recognized and agreed to what he called a gentlemens agreement toward space science to avoid contamination of other planets by earthborne organisms and vice versa.
This is why JAXA has tried and is trying very hard to prevent any sort of situation where this [contamination] situation could happen, he said.
If JAXA does succeed, Nozomi will still be able to conduct many of its original science missions, Nakatani said.
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