December 17 - 21, 2007 - Interplanetary Cruise Begins

With the successful completion of the initial checkout phase of its mission, Dawn began the interplanetary cruise phase. While other activities will be conducted occasionally, the project's focus now is on thrusting with the ion propulsion system to reach asteroid Vesta (and later dwarf planet, Ceres).


December 10 - 14, 2007 - More Instrument Tests Completed

The backup science camera was powered on for the first time this week and verified to be healthy and operating well. The primary science camera and the visible and infrared spectrometer completed additional tests, and both instruments continue to perform extremely well.


December 3 - 7, 2007 - Additional Camera Tests and Software Loads Completed

The primary science camera was operated again, acquiring images of stars as a further test of its performance. All indications are that it is operating excellently. Software that had been uploaded earlier in the mission continues to work well, so the same software was loaded this week into some of the backup locations.


November 26 - 30, 2007 - Updated Software Loaded in Main Computer

This week was devoted to updating the software on the main spacecraft computer. This was planned before launch. Files were transmitted to the spacecraft, computer memory was checked, and other activities were conducted on Monday and Tuesday in preparation for rebooting the computer on Wednesday to start using the new software. On Tuesday night, the computer rebooted on its own. All diagnostic information has been returned from the spacecraft and the event is being investigated. With the new software operating as expected, controllers have verified that the spacecraft is healthy and activities are proceeding as scheduled.


November 19 - 23, 2007 - Main Antenna Checked Out and New Software Uploaded

This week, the spacecraft was commanded to use its main antenna for the first time and measurements showed that it is in fine condition. New software was installed in one of Dawn's computers (and its backup), correcting a minor bug that was discovered shortly after launch.


November 12 - 16, 2007 - More Ion Thrusting Tests Completed

The week-long systems test of interplanetary cruise thrusting completed successfully on Monday. The third ion thruster was tested this week, and like the other two, it performed perfectly. The thruster operated at 4 throttle levels, including full power. In a separate activity, the mission operations team powered off the reaction wheels to test pointing control with hydrazine thrusters during ion thrusting.


November 5 - 9, 2007 - Dawn Begins Cruise Thrust Test

To test the readiness of all systems for the interplanetary cruise phase of the mission (planned to begin in mid-December), Dawn is conducting a one-week execution of all the activities that will be typical of a week in that phase. As most of the time will be spent thrusting with the ion propulsion system, the spacecraft began thrusting on Monday and now has thrust for 4 days without interruption.


October 29 - November 2, 2007 - More Checkouts Completed

The operations team conducted tests of special modes of the attitude control system while the ion propulsion system is thrusting. All tests showed excellent performance. Two of the three ion thrusters have been fully checked out. Tests began with the third thruster this week, and all were completed successfully. The device that emits electrons to ionize xenon was heated to drive off contaminants, and then the thruster ionized xenon (but was not commanded to accelerate it). In addition, the gimbal system that points the thruster in the required direction was operated for the first time in flight. The first test of thrusting with this thruster is not scheduled to occur until after other spacecraft tests are completed.


October 22 - 26, 2007 - Second Ion Thruster Checkout Completed Successfully

The mission operations team completed the checkout of a second ion thruster this week. In one of the tests, the thruster was operated for 27 hours continuously at 5 different throttle levels, and in two other tests it was operated at maximum power for 4 hours each time. All spacecraft systems performed extremely well.


October 15 - 19, 2007 - Science Instruments Checked Out

Dawn's science instruments were powered on and given their first health checks this week. The gamma ray and neutron spectrometer, imaging camera, and visible and infrared mapping spectrometer all operated perfectly.


October 8 - 12, 2007 - Ion Propulsion System Testing Continued

The ion propulsion system performed extremely well as Dawn operated two of its three ion thrusters this week. Testing of the second thruster included placing the spacecraft in an orientation in which sunlight gradually warmed some other components more than mission controllers wanted, and the spacecraft was commanded to end the activity early. The spacecraft remained healthy throughout.


October 1 - 5, 2007 - Ion Propulsion System Tested

Mission controllers completed the configuration of the spacecraft for routine operations on September 29. During the week, all the steps were completed to prepare for the first test of ion thrusting.


September 24 - 28, 2007 - Dawn Launches!!

Dawn had a beautiful ride to space on September 27. Launch was delayed one day from bad weather, and liftoff was delayed 14 minutes from a boat in the range safety zone. Following liftoff at 7:34 am EDT, all systems performed well, and the operations team at JPL received signals from the spacecraft about two hours later showing that it was healthy. Since then, operators have been checking telemetry and configuring the spacecraft for routine operations.


September 17 - 21, 2007 - All Systems Preparing for Launch

Despite two days of delays from bad weather, the payload fairing was installed on the Delta rocket this week, and all systems are on schedule for launch on September 26. The operations team has now tested and verified all computer files necessary for launch and early operations. All that needs to be completed before launch is fueling and other final preparations of the launch vehicle.


September 10 - 14, 2007 - Dawn Spacecraft Returned to Launch Pad

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.


September 3 - 7, 2007 - Preparations for Mission Operations Continue

The operations team continued development of command sequences to be used during the first phase of the mission, known as initial checkout. These commands will guide the spacecraft through activities to provide data for engineers to use in evaluating the health and performance of all subsystems. Meanwhile, plans were completed for transporting the spacecraft back to the launch pad next week.


August 27 - 31, 2007 - Operations Team Simulates Launch and Operations

The operations team conducted simulations at JPL this week covering the last 16 hours of countdown, launch, and early operations. The simulation supervisor intentionally created some problems, all of which the team handled successfully.


August 20 - 24, 2007 - Launch Period Established

This week, NASA chose September 26 to October 15 as Dawn's launch period. Computer files that will be used during the final countdown were tested on the spacecraft, demonstrating that they work correctly.


August 13 - 17, 2007 - Dawn Team Continues Preparing for New Launch Date

The Dawn operations team continued to develop new sets of commands and other computer files for the spacecraft to use, accounting for differences between the previous launch period and the new September - October launch.


August 6 - 10, 2007 - Launch Coordinates Calculated

Engineers completed calculations of the coordinates needed for the rocket to deliver Dawn to space for a launch on any day from September 7 through October 15. (The dates for Dawn's launch period will be established soon.) These data will be used to program the rocket and to compute the open and close times of the daily launch windows. Now, with the details of the new trajectory early in the mission, the operations team is refining commands it will use during the first few weeks of Dawn's flight.


July 30 - August 3, 2007 - Spacecraft Tests Completed

Engineers completed a series of tests that verified all subsystems are healthy after transportation from the launch pad back to Astrotech.


July 23 - 27, 2007 - Spacecraft Moved to Astrotech

The spacecraft and third stage were removed from the launch pad and transported to a clean room at Astrotech. The first and second stages of the launch vehicle will remain on the pad (until liftoff).


July 16 - 20, 2007 - Preparations Continue for Removal of Spacecraft from Launch Pad

The payload fairing (the rocket's nose cone) has been removed. Tests confirmed that the third stage may be moved safely without removing any of its liquid propellant, clearing the way for the spacecraft and mated stage to be transported from the launch pad to Astrotech.


July 9 - 13, 2007 - Preparations Underway for September Launch

Work has begun to remove the spacecraft from the launch pad and return it to the clean room at nearby Astrotech Space Operations. (The spacecraft will remain mated to the third stage.) Launch trajectories for September are being designed


July 2 - 6, 2007 - Launch Rescheduled for September

Because of consistently bad weather and technical problems with launch vehicle tracking systems off the coast of Africa, Dawn's launch has been rescheduled to September.


June 25 - 29, 2007 - Dawn Moved to Launch Pad

The Dawn spacecraft and third stage were transported from Astrotech to Space Launch Complex 17B at Cape Canaveral and installed on the second stage. Final checkouts and preparations for launch continue on all three stages of the launch vehicle and the spacecraft.
- Feature Story


June 18 - 22, 2007 - Spacecraft Mated to Third Stage, and Second Stage Mated to First Stage

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.


June 11 - 15, 2007 - Hydrazine Loaded, Spin Test Completed, Operations Rehearsals Conclude

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.


June 4 - 8, 2007 - New Launch Date Set, Xenon Loaded, Operations Rehearsals Conducted

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.


May 28 - June 1, 2007 - Dawn Spacecraft Prepared for Fueling

In preparation for loading xenon and hydrazine propellants, the Dawn spacecraft was moved to the fueling area at Astrotech.


May 21 - 25, 2007 - Final Operations Test with Spacecraft and Attachment of Solar Arrays

The final mission operations test with the spacecraft was completed successfully. Dawn's solar arrays were attached to the spacecraft and the system for deploying them in space was given one final test, which went very smoothly.

The Dawn project had a large display at JPL's Open House, attended by more than 32,000 people.


May 14 - 18, 2007 - Telecommunications Tests Conducted and Observations of Vesta Completed

The spacecraft conducted a successful series of radio communications tests with MIL-71, the facility at the Kennedy Space Center that replicates a Deep Space Network station. The Hubble Space Telescope observed Vesta, the first of Dawn's two destinations.


May 7 - 11, 2007 - Spacecraft Alignments Completed and Launch Rehearsal Conducted

The alignment of spacecraft components was verified and finalized this week, ensuring that antennas, ion thrusters, scientific instruments, and other devices are properly oriented. With mission control at JPL connected to the spacecraft at Astrotech in Florida, mission controllers conducted another successful simulation of the final 4 hours of countdown, launch, and the first 4 hours of spacecraft operations once Dawn is in space. (This was a test of the procedures used to control the spacecraft and assess its condition; the launch vehicle was not involved.)


April 30 - May 4, 2007 - Comprehensive Performance Tests Completed

The spacecraft successfully completed two weeks of comprehensive performance tests. In these tests, each engineering subsystem and each instrument is operated extensively to verify it continues to function as required. The first run of the same tests was conducted in 2006, so engineers can verify that now that the spacecraft is in final preparation for launch, no unexpected changes have occurred as a result of the environmental tests or the shipment of the spacecraft.


April 23 - 27, 2007 - Mission Control Simulation of Ion Thrusting Completed

Mission controllers completed a four-day simulation of the procedures to be used to command and monitor the spacecraft for the first firing of the ion propulsion system after launch. This activity, known as an operational readiness test, used a simulator of the spacecraft to provide realistic responses to commands as well as signals for engineers in mission control to interpret. This simulation included the steps that would be followed to check the validity of the commands if the launch were delayed by a day, which would cause the alignment of the ion thruster relative to Earth to change. (A launch delay can occur as a result of bad weather or problems during the final countdown that cannot be resolved during the daily launch window.) Meanwhile, the final comprehensive performance tests are being conducted on the spacecraft in Florida to verify that each subsystem is still working correctly.


April 16 - 20, 2007 - Work on Spacecraft in Full Swing in Florida

Dawn's solar arrays, which convert sunlight into electricity, arrived at Astrotech Space Operations this week, where work continues on the spacecraft. (The solar arrays were removed from the spacecraft in December.) Version 6.1 of the software for the main spacecraft computer was loaded into the computer. Tests to show that software could be loaded onto the spacecraft while it is in space were completed successfully.


April 9 - 13, 2007 - Dawn spacecraft shipped to Florida

The spacecraft was trucked from the Naval Research Laboratory in Washington, DC to Astrotech Space Operations near Cape Canaveral this week.  It was unpacked and moved into a clean room, and inspection showed it to be in fine condition after the trip.


April 2 - 6, 2007 - Completion of Additional Testing and New Launch Date

An acoustic test, in which powerful sound was directed at the spacecraft (similar to the noise of launch), was completed at the Naval Research Laboratory. This verified that the work to remove and reinstall the high voltage electronics assembly did not harm the spacecraft. To accommodate a change in the schedule for assembling the components of Dawn's Delta II launch vehicle, the launch date is shifted 10 days to June 30. The change will have no effect on mission objectives or science.


March 26 - 30, 2007 - High voltage electronics reinstalled and leak checks completed

The high voltage electronics assembly (the unit that governs the delivery of electrical power from the solar arrays to the onboard subsystems) completed testing in a thermal vacuum chamber at JPL and has been reinstalled on the spacecraft at the Naval Research Laboratory. Tests of the ion propulsion system and the reaction control system (the system that uses small conventional thrusters to aid in orienting the spacecraft in the zero-gravity of spaceflight) verified their integrity, with no leaks being found.


March 5 - 9, 2007 - Successful completion of tests coordinating flow of information between the Dawn spacecraft and ground systems network

Dawn has successfully completed all of the tests focused on the flow of information between the spacecraft and the network of ground systems that could be conducted before the spacecraft is in Florida. (Testing in Florida will be conducted with a facility near the launch site that replicates the characteristics of NASA's Deep Space Network communications facilities.) The content of version 6.0 of the software that runs in the main spacecraft computers was finalized this week.