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On-Orbit Mission Updates


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The two Orbital Express satellites have completed their end-of-life maneuver and have been decommissioned.

The end-of-life maneuver included a long-range sensor characterization and rendezvous experiment designed to demonstrate that the ASTRO servicer could transition between an absolute (externally supplied) navigation state to a relative navigation provided by its on-board sensors, at a range of up to 400 km, and then enter back into a track mode with the NextSat client satellite.

The maneuver was initiated July 16, with the ASTRO demating and moving away from the NextSat. The ASTRO sensor suite and navigation system lost track of the NextSat at a distance of 310 km. At that point, ground operations provided the ASTRO a Space Surveillance Network-derived navigation fix for the NextSat, and the ASTRO started moving towards that predicted position. The ASTRO’s on-board sensors were successful in acquiring the NextSat, and the ASTRO went into an track mode to stay between 500 and 1,000 m behind the NextSat.

The ASTRO remained in the track mode for approximately 24 hours, then maneuvered to 500 m in front of the NextSat. Ground operations then commanded the ASTRO to maneuver to a co-elliptic orbit, drifting backwards at approximately 70 km/hr. This maneuver will ensure that the ASTRO and NextSat will not re-encounter each other following the satellites’ decommissioning. The ground operations team next started the decommissioning sequence for the NextSat, opening solar array switches, turning solar panels away from the sun, and decommissioning onboard computers. The team confirmed successful decommissioning of the NextSat early July 21. Decommissioning for the ASTRO consisted of jettisoning remaining propellant and decommissiong its computers. Decommissioning of the ASTRO was confirmed July 22.

The DARPA Orbital Express program met all of its mission success criteria. The end-of-life maneuver demonstrated a capability for long-range rendezvous and track. (Posted 7/23/07)


On-orbit video of scenario 7 (the 4 km separation demonstration conducted June 22). The jumps in the video are due to that fact that it is made up of a composite of still pictures; the video runs faster than real-time. The video shows views taken from both the visual and infrared cameras. (Posted 7/12/07) Video High (.avi format 56MB)


On-orbit video of scenario 7 (the 4 km separation demonstration conducted June 22). The jumps in the video are due to that fact that it is made up of a composite of still pictures; the video runs faster than real-time. The video shows views taken from both the visual and infrared cameras. (Posted 7/12/07) Video High (.avi format 56MB)


On-orbit video of scenario 5 (conducted June 16). The jumps in the video are due to that fact that it is made up of a composite of still pictures; the video runs faster than real-time. (Posted 7/12/07) Video High (.avi format 34MB)


“Family portrait” picture of both the ASTRO and NextSat, taken from the robotic arm during the 4 km separation demonstration conducted June 22. (This is the only on-orbit picture that includes the ASTRO since the NextSat does not have any cameras.) (Posted 7/12/07) Picture


We are continuing to process pictures and videos from past demonstrations and will be posting them as they become available. (Posted 7/12/07)


The Orbital Express has completed its final and most challenging unmated rendezvous and capture scenario (scenario 8-2). The operation was completely autonomous, with the two satellites operating at distances of up to 7 km apart, and often with only passive optical and infrared imaging for guidance. The mission marked the second successful grapple and capture of the NextSat by the ASTRO, using its robotic arm.

The scenario started early June 27. The ASTRO demated from the NextSat and retreated along the negative velocity vector (-V-bar), this time to a distance of 7 km. Sensor performance was excellent.

Upon reaching the the 7 km turnaround point, the ASTRO autonomously fired its thrusters to initiate a return to the NextSat. Upon reaching the 4 km point, the ASTRO entered an extended "racetrack" mode, demonstrating the spacecraft's ability to perform precision standoff at medium ranges. After six hours, the ASTRO departed the racetrack for a 1 km hold point, then fired again to reach 120 meters.

The ASTRO then performed a 3x orbital rate circumnavigation of NextSat, allowing ASTRO to visually inspect its client from various attitudes. The ASTRO executed a hold at 120 meters (on the +V-bar), and then entered the NextSat approach corridor and grappled NextSat with the robotic arm.

The first intervention from the ground occurred at this point, when the ground operations team observed a misalignment of the two spacecraft and sent a series of commands to properly translate and align the NextSat for final mating. The direct capture mechanism was automatically engaged and the arm released and retracted, and the two satellites were once again mated together.

In the mated configuration, the satellites performed battery and propellant transfers, and the ASTRO removed and re-inserted a spare flight computer with its robotic arm. This spare had functioned as ASTRO's primary sensor processor for the past three unmated scenarios. During the flight computer re-insertion process, there was a misalignment between the computer and its ORU Interface Assembly. The ground operations team halted the re-insertion attempt, extended the robotic arm back out slightly to restart the re-insertion activity. This second insertion was successful, concluding the demonstration and the Orbital Express mission.

Video 1 is a compilation of VisSTAR sensor data as the ASTRO approaches NextSat. The VS2, or wide field of view camera, is shown at bottom left in the video, with VS1, the narrow field of view or long range camera, shown at top left. The infrared camera is at the top right.

Video 2 is from the VS2 or wide field of view camera. It starts after the ASTRO’s robotic arm has grappled the NextSat, as the arm moves the NextSat to preberth and then to berth and mate. (Posted 7/20/07)
Video 1 High (.avi format 38MB)
Video 2 High (.avi format 112MB)


Over approximately 18 hours, the Orbital Express spacecraft conducted the first-ever autonomous capture of a satellite by another satellite using a robotic arm.

The ASTRO satellite backed away from the NextSat and autonomously retreated along the negative velocity vector (-V-bar) to a distance of 4 km. All sensors worked well throughout. Once it reached its turnaround point, the ASTRO initiated a series of maneuvers to close with the NextSat and remate. The firing plan first targeted 1 km, then 120 meters, where the ASTRO stationkept for one orbit before proceeding. The ASTRO transitioned from 120 meters to 60 meters, entering the NextSat approach corridor and deploying the robotic arm in preparation for grappling. The NextSat maintained a solar inertial pointing state during the approach. The ASTRO then entered the capture box (< 1 m separation) and successfully grappled the NextSat. The ASTRO's arm script then executed a move to bring the NextSat to the pre-berth position, and later, berth position. Next, the direct-capture mechanism was engaged, the arm released and retracted, and the ASTRO and NextSat were fully remated.

DARPA’s Orbital Express program will conduct its final demonstration, a 7-km autonomous rendezvous and capture, later this week. (Posted 6/25/07)

For updated video and a “Family portrait” picture of both the ASTRO and NextSat please see the 7/12/07 posting.


IRC IRCAM View during approach to FFC

IRC IRCAM View of NextSat during approach

IRC IRCAM View of NextSat at 120 meters

VisCam 1 View of NextSat during approach

VisCam 1 view during approach operations

VS2 Viscam 2 view of NextSat

Viscam 2 view during Approach operations

Nextsat at 14 meter range during departure




Early on June 16, the Orbital Express team successfully executed Scenario 5, in which the ASTRO servicing spacecraft conducted a 60 x 120 meter circumnavigation of the NextSat client satellite.

The ASTRO autonomously demated from the NextSat and retreated to a separation distance of 60 meters. The ASTRO's guidance then executed a flawless circumnavigation of NextSat at distances of up to 120 meters and as much as 40 meters out of plane. Approximately 4.5 hours after demating, the NextSat was commanded to a -R-bar attitude (nadir pointing, with its capture mechanism pointing at

This is an extremely demanding approach trajectory, from the standpoint of orbital mechanics (natural motion tends to force the vehicles apart) and client visibility (Earth is in the field of view at all times, and represents a source of potential false targets). The ASTRO entered the approach corridor at the top of the R-bar and successfully captured and mated with NextSat.

The scenario was conducted without any intervention from the ground-based mission operations team.

All of the ASTRO's sensors, including both wide-field and narrow-field optical cameras, the infrared camera, the laser-based Advanced Video Guidance Sensor, and a laser rangefinder, were engaged during this difficult series of maneuvers, and all performed well. (Posted 6/18/07)

For updated video please see 7/12/07 posting.

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Orbital Express has resumed its demonstration activities. The NextSat transferred a battery orbital replacement unit to the ASTRO, and the ASTRO transferred fuel to the NextSat. The Orbital Express team hopes to resume unmated activities following the review of Scenario 3-1 events. (Posted 5/31/07)


Updated information on the 5/19 remating of the ASTRO and the NextSat is available in today’s press release. (Posted 5/21/07)


ASTRO and NextSat are again mated together. More details will be available on Monday or Tuesday. (Posted 5/20/07)


During Scenario 3-1 execution on the evening of May 11, Orbital Express encountered a serious sensor flight computer anomaly on the ASTRO while stationkeeping at 10 meters separation distance from the NextSat. Onboard fault protection reacted immediately, placing the ASTRO into an abort trajectory which carried it to a hold-point 120 meters from the NextSat. The Orbital Express team has spent the past several days recovering from this fault and from problems associated with loss of relative navigation at the longer-than-anticipated separation distances for this scenario. The ASTRO has since coasted at distances of up to several kilometers from the NextSat. Both vehicles are safe. The ASTRO powered up its redundant sensor flight computer and is processing sensor data nominally. The team is in the process of developing a recovery scenario for ingress and remate, and hopes to execute this ingress in the next several days. (Posted 5/15/07)


The ASTRO and the NextSat completely unmated and separated to a distance of 10 meters apart from one another. They flew in formation for approximately an hour, and then re-mated again. All activities were conducted for the most part out of contact with the ground and were accomplished by the satellites operating autonomously. This is the first step toward Orbital Express’ final goal of separating to a distance of 7 km and remating. The video is a composite of still pictures and events happen faster than actual time. (Posted 5/7/07) Video High (.wmv format 18MB)
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In late evening April 26, the Orbital Express team encountered an anomaly while completing a camera characterization procedure.

As part of the procedure, the ASTRO satellite's robotic arm grappled the NextSat satellite. The ASTRO then released the capture mechanism holding NextSat to ASTRO and used the robotic arm to move the NextSat into a series of positions and attitudes in front of the ASTRO’s cameras for sensor characterization. This effort was fully successful.

When the arm returned the NextSat to its capture position, the ASTRO's capture mechanism engaged the NextSat but the arm failed to properly release the NextSat when commanded to do so. Instead, as the arm retracted, it canted the NextSat to one side by several degrees, eventually triggering an abort in the arm's software script.

Throughout, the NextSat remained captured to the ASTRO via the capture mechanism.

Within 24 hours, the team was able to free the arm from the grapple fixture on the NextSat, and reseated the NextSat onto the capture mechanism, and both satellites are in excellent condition.

The Orbital Express team continues to investigate the phenomenology behind the binding. Scenario 2 activities, which includes a 10-meter rendezvous and capture operation between the ASTRO and the NextSat spacecraft, are still expected to start May 5. This will be the first time that the Orbital Express satellites are fully separated from one another. (Posted 5/1/07)


Orbital Express will conduct its first truly unmated operation, Scenario 2-1, on 5/5/07. During this experiment, the ASTRO will release the NextSat and retreat to a distance of approximately 10 meters, then hold position for an extended period. The ASTRO will then rendezvous with the NextSat and capture it, using the Starsys capture mechanism. Further hydrazine and battery transfers are planned following the remating event. Orbital Express will conduct additional unmated operations throughout May and early June. The video is a computer animation illustrating Scenario 2-1. (Posted 4/27/07) Video High (.wmv format 73MB)
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Video of the remating is now available. Video (a composite of still pictures) shows NextSat held by the robotic arm and moved into berthing position. The robotic arm releases NextSat, which is then grabbed by the ASTRO capture mechanism and pulled into a mated position. (Posted 4/23/07) Video (.wmv format 2.3MB)


ASTRO and NextSat today separated for the first time, and the launch ring between them was safely ejected. The two spacecraft are now back in the mated configuration. See the 4/18/07 press release for details. The video of the separation is a composite of still pictures, and shows NextSat separating from the launch ring and then the robotic arm closes in on the satellite and grapples it. The ring eject video is also a composite of still pictures. (Posted 4/18/07) Video High NextSat separates
Video Med NextSat separates
Video Low NextSat separates

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Picture Ring eject
Picture Ring eject

Picture NextSat prepares to remate with ASTRO
Picture NextSat prepares to remate with ASTRO


Orbital Express will begin unmated operations on 4/16/07. The video is a computer animation of the first activity planned, during which ASTRO’s robotic arm will grapple NextSat and move it out the way. Following jettison of the launch ring, the robotic arm will move NextSat to enable sensors onboard ASTRO to be checked and calibrated. The experiment concludes with NextSat again in a mated configuration with ASTRO. On-orbit video from the experiment will be posted next week; the on-orbit video will provide a view of the experiment from cameras onboard ASTRO. (Posted 4/13/07) Video High (.wmv format 70MB)
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Orbital Express performed the first autonomous battery Orbital Replacement Unit (ORU) transfer. This first transfer moved the battery from ASTRO, where it has been since launch, and placed it on Ball's client satellite, NextSat, where it is now integrated into NextSat's power system. When installed on NextSat, this extra battery allows NextSat to hold Local Vertical Local Horizontal for longer durations; this will become important during unmated operations, when NextSat is not tracking the sun. This transfer marks the first time one satellite has autonomously transferred a battery to another spacecraft using a robotic manipulator arm. Video depicts the survey of ORU locations following the transfer. (Posted 4/12/07) Video High (.wmv format 7.5MB)
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The first Orbital Express demonstration, Scenario 0-1, was very successful. The ASTRO spacecraft autonomously completed a coupler system mating and leak check on March 31, and then performed a pressure-fed hydrazine propellant transfer to NextSat, early on April 1. ASTRO transferred just under 32 pounds of hydrazine to the NextSat client, meeting the scenario objective.

This first transfer was performed at the lowest autonomy level, which requires multiple ground approvals for the spacecraft to execute the operation. In the case of Scenario 0-1, a total of 23 approvals were needed during this first coupler mate and hydrazine transfer operation.

On the afternoon of April 2, ASTRO successfully used its pump to transfer 19 pounds of hydrazine to NextSat. The spacecraft will perform a reverse transfer (NextSat to ASTRO) on April 4.

Later this week, ASTRO will transfer a battery from its bay to a similar bay onboard NextSat. The battery is fully functional and will integrate into NextSat's electrical power system. April 16 marks the ejection of the separation ring joining the two spacecraft. This will allow the operations team to perform unmated rendezvous and capture activities. (Posted 4/4/07)


Global mated survey of the two spacecraft by the arm camera. The video was created from 1,600 still pictures taken by the camera. (Posted 3/30/07). Pictures
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