An artist's interpretation of NASA's Dawn spacecraft in flight.
HOUSTON, Texas - NASA is taking another look at the decision to cancel the Dawn mission that would explore two large asteroids in the solar system.
The space agency officially killed the mission earlier this month, citing an independent assessment that flagged over two dozen major issues in need of resolution before Dawn was ready to go.
The abandonment of the mission was also due to its increased cost growth of 20 percent over Dawn's confirmation cost cap of $373 million, as well as a 14-month or more delay in launching the spacecraft, NASA officials said at the time.
The death of Dawn has stirred up anger in scientific circles, both in the United States and abroad - a fact that surfaced here earlier this week at the 37th Lunar and Planetary Science Conference (LPSC).
When pressed by scientists to clarify whether or not the Dawn mission has been restored, NASA Associate Administrator for Science, Mary Cleave, said NASA is responsive to Congressional language that dictates "if we get to a certain percentage cost overrun we have to review a project. And if it gets to another percentage Congress will zero the money going in and we will be in this limbo with no money going in."
Another reply regarding the status of Dawn came from Andrew Dantzler, director of NASA's solar system division in Washington, D.C.
"I really can't get into the details on Dawn," Dantzler told the LPSC gathering, but noted that the cancellation "is under review by our management." Because of that fact, he added, it would not be appropriate to get into specifics.
The cost to stand down Dawn was slated not to be more than $5 million dollars and hasn't been, Dantzler said. "Continuing Dawn is significantly more," he said.
Dantzler said that termination of a mission or a budget cut "is a very serious issue," with NASA doing everything it can not do that.
In terms of the technical problems of Dawn, Dantzler said that "it would not be wise to go into technical detail."
While the findings of a new review are yet to play out, NASA's cancellation of Dawn in the first place incensed scientists, not only those in the U.S. but in other countries taking part in the mission.
"It's totally unacceptable what's happening now," said Gerhard Neukum, professor of planetary sciences at Freie Universit?t Berlin in Germany and a member of the Dawn team.
There is international involvement in Dawn, Neukum pointed out. "NASA has responsibility to their cooperation partners first and foremost before they go to the last resort of canceling a mission," he told SPACE.com.
"It's absolutely ridiculous what NASA is doing," Neukum said, "because most of the money has been spent."
Neukum noted that "the mission is practically ready to go. There are a few technical problems that are overstated on NASA's side. It's not a well-based, neutral review in my opinion."
"We didn't know what was going on," Neukum said. "If there is cost-overrun you just can't go on," he admitted, but added: "You have to review it and see where it comes from and then try to remedy things. You find the cause and possibly save the mission. That should be the first goal."
The response from NASA officials here at the LPSC meeting concerning the cancellation of Dawn seemed to Neukum as if they cancelled the mission to free some money for other purposes.
"This is absolutely unacceptable what's going on there. It was unilateral, without prior warning and no discussion," Neukum said. "I know that there were some other technical problems, but no fundamental ones. They all could be fixed," he explained.
Dawn is under the rubric of NASA's econo-class Discovery program. It was selected in December 2001 to be developed on a fast-paced schedule and at modest cost compared to so-called "flagship" missions.
Using ion propulsion, Dawn's objective has been to reach asteroids 4 Vesta in 2011 and 1 Ceres in 2015. By surveying those mini-worlds up-close, scientists want to glean clues about the formation of the solar system.
Dawn is managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California with Orbital Sciences Corporation of Dulles, Virginia developing the spacecraft.
The mission was slated for liftoff in mid-June 2006, but late last year was placed in "stand down" mode. Mounting technical issues and cost growth in the project led to the stand down, with an independent assessment team tagged with the duty to look into the problems.
The scuffle over Dawn was spotlighted by Jonathan Lunine, Professor of Planetary Sciences and of Physics at the University of Arizona in Tucson during a major talk at LPSC on the future of solar system exploration.
"Dawn -- which actually did get canceled but is now on some kind of life-support...or there's some religious ceremony in which it's being resurrected -- if it does go to two very large asteroids, Ceres and Vesta, it is a very important mission."