NASA | Dawn Mission - Discussion and Updates

Dawn Spacecraft Prepares for Launch July 7, 2007
Spacecraft Mated to Third Stage, and Second Stage Mated to First Stage, June 18 - 22

Dawn spacecraft damaged but still set for launch
* 20:37 13 June 2007
* NewScientist.com news service
* David Shiga

NASA managers got a scare this week when a wayward wrench damaged the Dawn spacecraft. But the mission's chief scientist says the damage can be fixed in time for the spacecraft's planned 7 July launch.
image source: http://space.newscientist.com/data/images/ns/cms/dn12060/dn12060-1_600.jpg

Countdown To Dawn
by Dr. Marc D. Rayman
Cape Canaverl FL (SPX) Jun 27, 2007

Now only two weeks away from its planned launch, Dawn is eagerly awaiting the beginning of its cosmic adventure. Once the xenon and hydrazine propellants were loaded the spacecraft was ready for its final balancing and weighing. As we will see below (that direction applies only for those of you reading this in a gravitational field), during part of its flight on the Delta 7925H-9.5 rocket, the spacecraft will be spun, and it is crucial that it satisfy certain requirements on how well balanced it is so the rocket remains stable.

image source: http://www.spacedaily.com/images/dawn-asteroids-bg.jpg

image source: http://dawn.jpl.nasa.gov/portal_images/nasa_logo.gif

Spacecraft Mated to Third Stage, and Second Stage Mated to First Stage
June 18 - 22
The spacecraft was connected to the third stage of the launch vehicle at Astrotech. At Space Launch Complex 17B, the second stage was lifted into place on the first stage.

Hydrazine Loaded, Spin Test Completed, Operations Rehearsals Conclude
June 11 - 15
Hydrazine propellant, used as one means to rotate the spacecraft in space, was loaded. Spin tests were completed and balance masses were added to the spacecraft. During preparations for the spin tests, minor damage to the back of a solar panel occurred when a tool made inadvertent contact with it. The small affected area was patched over the weekend, and the process did not affect the launch date.

The mission operations team conducted more simulations of activities to be conducted in flight. The entire set of simulations to be executed before launch has now been completed.

New Launch Date Set, Xenon Loaded, Operations Rehearsals Conducted
June 4 - 8, 2007
Because of delays in assembling Dawn's rocket at Cape Canaveral, Dawn's new launch date is July 7. Xenon propellant for the ion propulsion system was loaded into the spacecraft. Meanwhile, the mission operations team conducted additional simulations of launch and early flight activities.

Dawn Spacecraft Prepared for Fueling
May 28 - June 1, 2007
In preparation for loading xenon and hydrazine propellants, the Dawn spacecraft was moved to the fueling area at Astrotech.

(Continued...)

Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity ten times that of chemical rockets.

image source: http://dawn.jpl.nasa.gov/mission/images/ion_head.jpg

image source: http://dawn.jpl.nasa.gov/mission/images/CR-1845.gif

image source: http://dawn.jpl.nasa.gov/mission/images/CR-863.gif

The Atlas delay is not expected to move the
Sept. 26 launch of the Dawn spacecraft
on a $450 million mission to the asteroid belt.

Sept. 26 Dawn
The Dawn Mission will be the first time a spacecraft will orbit two planetary bodies
on a single voyage as it studies Ceres and Vesta.
Launch window: 7:25 to 7:54 a.m. EDT

Dawn Spacecraft Returned to Launch Pad
September 10 - 14

On September 11, Dawn and the mated third stage were moved from Astrotech to Cape Canaveral's Space Launch Complex 17B where they were hoisted into place atop the second stage of the Delta launch
vehicle. Brief tests of the spacecraft subsystems showed Dawn to be in good health. As part of the planned preparations for launch on September 26, the Kevlar cords that have held the solar arrays in their stowed position since prior to the planned June/July launch were replaced with fresh ones, and the new cords were adjusted to the correct tension for launch.

SOURCE | dawn.jpl.nasa.gov | Read more...

NASA Spacecraft Is a Go for Asteroid Belt

09.25.07

CAPE CANAVERAL, Fla. -- Launch and flight teams are in final preparations for the planned Sept. 27 liftoff from Pad 17-B at Cape Canaveral Air Force Station, Fla., of NASA's Dawn mission. The Dawn spacecraft will venture into the heart of the asteroid belt, where it will document in exceptional detail the mammoth rocky asteroid Vesta, and then, the even bigger icy dwarf planet Ceres.

SOURCE | dawn.jpl.nasa.gov | Read more...

Image right: Inside the mobile service tower on Launch Pad 17-B at Cape
Canaveral Air Force Station, technicians secure both halves of the fairing
around the Dawn spacecraft to the upper stage booster of the Delta II
rocket below. Image credit: NASA

+ Larger view

The 13-story rocket, which is equipped with supersized solid rocket boosters,
is scheduled to blast off from Launch Complex 17 on the south end of the Cape
at 7:20 a.m. EDT.
The launch window will extend until 7:49 a.m. EDT.

Live NASA TV coverage of the countdown and launch will be webcast here in The Flame Trench
beginning at 5:15 a.m. EDT.