. 24/7 Space News .
A Rising Mercury For Japan


Tokyo - June 12, 1998 -
The Institute of Space and Astronautical Science [ISAS] is planning an ambitious mission to Mercury as soon as August 2005. The mission, which could involve significant articipation by the Jet Propulsion Laboratory, will end a dry spell of over twenty years during which visits to the sun's nearest neighbor have been put on the back burner.

"Why Mercury?... because it's the least known and least understood of the inner planets," said Hirobumi Saito, ISAS' project planner for the Mercury probe, when announcing the plan at the 21st International Space Technology and Science Symposium, Omiya, north of Tokyo, May 28.

Saito said that ISAS hopes to better understand the mechanics of solar system evolution and history by examining the size, make up and internal structure of Mercury's inner core and magnetosphere, collecting data on surface structure and composition, and mapping the arid planets' surface via a multiband camera.

The last visit to Mercury came with three Mariner 10 fly-bys over 1974 and 1975 as part of a secondary mission after the NASA probe's had finished with their main target - Venus. The discovery of a faint helium atmosphere and Mariner's incomplete monochrome mapping raised more questions than they answered, said Japanese scientists.

"There are many problems with understanding Mercury's atmosphere. We know Mercury is quite different to the other inner planets but we don't even know what Mercury's mass is," said ISAS' Ysunori Matogawa, director of external affairs.

To answer some of these questions, ISAS plans to park 12 mission instruments as part of a 50 kilogram package in a 300 km orbit and is actively seeking partners, particularly from JPL, to contribute expertise to the scientific missions, said Saito. The camera could produce 30 meter resolution pictures. A 300 kilogram mini-satellite firing projectiles into Mercury's surface is also a possibility.

"The most important thing to remember is that the last Mariner only mapped only 50 percent of the surface. The other half is a complete mystery. That's the most exciting part of this mission," said ISAS orbit design laboratory member Hiroshi Yamakawa, who has just returned from discussions with JPL over US scientific contributions to the mission.

"Absolutely nothing has been formally agreed on, but JPL are particularly interested in s mapping and studying Mercury's magnetosphere."

While still in the conceptual design phase, several difficult decisions have been made as to the probe's trajectory and how it will avoid being cooked in Japan's toughest expedition to date.

Firstly, assuming the August 2005 launch, ISAS has decided to use a triple swing-by trajectory which in 4 years will see the 1.5 ton probe loop around Venus in 2006 and 2007 and Mercury itself in Jannuary 2008 before reaching parking orbit on Sept. 30 2009. The probe will also be driven by new ion engines under development by Toshiba.

Approaching to within 37 million kilometers of the sun, the 2.2 meter diameter, 4.4 meter long probe will be spin stabilized and covered in reflective cells to disperse and shield it from 260 C. temperatures. This will avoid relying on a complex attitude control system and a heat shield as Mariner 10 did, delivering a simple reliable design, according to Saito.

"Mercury is tough to reach, but thermal control is always going to be the biggest problem. The harsh environment will be the driving force behind the design," he said.

While the project has yet to be funded, ISAS personnel say they are confident of getting a budget. Initially the probe, which will either be designated Muses-D or Planet-C, will have to be approved by ISAS' internal space science committee this summer with an application for funding to Japan's Space Activities Commission in 1999. The internal review is considered the higher hurdle as Japan's space budget is expected to recover after 2000.

"We're positive we'll get funding if we can pass the space science committee," said Junichiro Kawaguchi, ISAS' Muses-C asteroid return mission manager, May 28.

Development costs will be held down by extensively cannibalizing technologies developed from ISAS's growing family of probes and slicing a year off its traditional six year development program. The mission will also drive improvements in ISAS's communications infrastructure, with upgrades planned to the Institute�s 64-meter diameter antenna after 2001 at Usuda, said Saito.

Detailed cost estimates have yet to be worked out, according to Matogawa, but would be around 10 billion yen (70 million) for the mission, excluding launch costs either by ISAS' Mu-5 or the H2A.

  • ISAS

    Related Links



    Memory Foam Mattress Review
    Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
    XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


    California Wins Minotaur Launch Contract
    White Plains N.Y. - June 11, 1998 -
    Spaceport Systems International (SSI), a limited partnership between ITT Industries and California Commercial Spaceport, Inc. has been selected for the first Minotaur space launch. Under the contract awarded by the U.S. Air Force, SSI will provide commercial payload processing, and range and launch site services for payloads being developed jointly by the U.S. Air Force Academy and Weber State University. The satellite launch, scheduled for late 1999, will be the first launch from SSI's California Spaceport.























  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement