Atlantis gifts TriDAR to Orbital’s Cygnus for ISS rendezvous and docking

by Chris Bergin

Adding to the long list that is her legacy, Atlantis’ successful final test of Neptec’s TriDAR rendezvous and docking system has resulted in Orbital completing a deal to use high tech sensors on their Cygnus spacecraft. With the orbiter’s also testing DragonEye for SpaceX’s Dragon spacecraft, the two commercial vehicles will “Tally Ho” the ISS via the path finding conducted by Shuttle.

STS-135’s TriDAR tests:

The Neptec TriDAR vision system – with the support of NASA and the Canadian Space Agency – provides real-time visual guidance for navigation, rendezvous and docking procedures. The system has proved its worth by flying on three shuttle missions, previously with Discovery on STS-128 and STS-131, prior to the recent trip with Atlantis on STS-135.

For the Atlantis mission the flight hardware – based on a combination of high-precision, near-field triangulation with a long-range Time-of-Flight (LiDAR) system – was modified to improve thermal stability of optics and add a calibration shutter to the thermal imager.

“Purpose: Demonstrate Rendezvous and Docking (AR&D) sensor technology that does not require cooperative targets.TriDAR provides 6 degree of freedom relative position and attitude without using reflectors. Operates by matching 3D data from a LIDAR to the known shape of the ISS,” noted Neptec’s STS-135 TriDAR presentation (L2).

“A Thermal imager is used to provide guidance data for long range operations. All tracking performed and displayed to the crew in real-time. Fully automatic target acquisition (no external seed). Enabling technology required for future exploration activities (satellite servicing, non-cooperative, tumbling targets etc).”

Its performance with Atlantis during rendezvous was impressive, with the TriDAR-created video of the acquisition of the International Space Station, showing how the system tracked the orbital outpost from 34km out, all the way through to Atlantis’ docking.

Arguably more impressive was the footage from the undocking and half lap flyaround of the Station, with TriDAR operated in imaging mode.

Given real-time tracking of undock and flyaround had already been previously performed during STS-131, the Neptec TriDAR team took the unique opportunity to produce 3D and thermal movies of the last Shuttle based ISS flyaround operation.

“Imaging mode constantly acquires 3D point cloud and thermal imager data. Acquired 3D data and range to centroid was displayed to the crew in real-time. Data collected can be used post flight to test algorithm enhancements and support system simulation validation.”

Neptec noted that the 3D Triangulation and LIDAR Laser Range images were collected simultaneously, utilizing a triangulation subsystem based on OBSS (Orbiter Boom Sensor System) LCS (Laser Camera System) technology.

The system worked so well that Commander Chris Ferguson took time during the undocking and flyaround phase to pass on thanks to the TriDAR team, before CAPCOM noted they were most likely listening in live – as they were.

STS-135 Specific Articles:

“Thermal Imager Data: Intended for longer range operation. Can generate “star tracker” type bearing data day or night. Acquired ISS images throughout undock and flyaround. Excellent performance from new shutter and IR camera. Collected ~1500 Thermal images,” added the presentation.

“Video Summary: All thermal images collected automatically. IR camera performed periodic self-calibration using internal shutter. 640×480 native resolution. Color coded to enhance visuals (red warm, blue cold).”

TriDAR has applications beyond rendezvous and docking, with short and long-range sensing capabilities. The system is being developed as a navigation system for lunar rovers, vehicle inspection, and will enable helicopter pilots to land in inhospitable and obscured environments.

However, an already confirmed role will be with Orbital’s Cygnus vehicle, which is tasked with carrying out cargo runs to the ISS from next year as part of the Commercial Resupply Services (CRS) contract with NASA.

“We are thrilled to be a part of this exciting next step of space exploration,” said Mike Kearns, Neptec VP for Space Exploration.

“With our operations on STS-135 wrapping up, we are proud to say TriDAR exceeded our expectations on its three separate shuttle flights and we are pleased to announce that the system will be an integral part of the ISS fleet of resupply vehicles.”

The Cygnus advanced maneuvering spacecraft is being developed by Orbital to conduct eight missions by 2015, carrying approximately 20,000 kg of cargo to the ISS as well as disposal of ISS waste.

It will ride uphill on the Orbital Taurus II launch vehicle from its Wallops launch site.

The Cygnus system is based on heritage from Orbital and its partners’ existing, flight-proven spacecraft technologies. The spacecraft consists of a common service module and a pressurized cargo module. Cygnus will carry crew supplies, spares and scientific experiments to the ISS.

The pressurized cargo module is based the on the Multi-Purpose Logistics Module (MPLM), developed by Thales Alenia Space for NASA, a common payload to be featured in shuttle missions – with the shuttle tested TriDAR now added to the list, a legacy respected by Neptec.

“The TriDAR program is a textbook example of what can be done when government and the private sector work together,” said Neptec president and CEO Iain Christie.

“It is bittersweet for all of us involved with the space program as we wrap up the Shuttle era, which has been a central part of our lives.

“(However,) this announcement shows we are taking our knowledge and experience from that program and continuing to make important contributions to the Space Station and beyond.”

To read about Atlantis and her sisters – from birth, processing, every single mission, through to retirement, click here for the links:

Click here for the amazing MaxQ Entertainment STS-135 Mission Review Music Video:

(Images: Via L2, Neptec and Orbital. Further articles on Atlantis will be produced during her down processing, driven by L2′s STS-135 Special Section which is continuing to folow the mission at MMT/MER level through to post flight IFA, surrounded by a wealth of FRR/PRCB/MER/MMT and SSP documentation/pressentations, videos, images and more.

(As with all recent missions, L2 is providing full exclusive level mission coverage, available no where else on the internet. To join L2, click here:

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