The Space Communications and Navigation (SCaN) program places the three prime NASA space communications networks, Space Network (SN), Near Earth Network (NEN) (previously known as the Ground Network or GN), and the Deep Space Network (DSN), under one Management and Systems Engineering umbrella. It was established in 2006. It was previously known as the Space Communications & Data Systems (SCDS) Program.
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Transcription
[ Music ] Okay SIM control we're ready to go to run. Thank you. Well Jim, it looks like the GPS residual's down. They ought to be calling us here any minute. Yeah I agree. It's looking pretty good. Probably just waiting on C-band tracking. Discovery, take GPS. Copy. Take GPS. All right, looks like it took. Yup. Well Jim, you ready to get some lunch? That was a great run. Yeah I agree. Let's do it. All right. Maybe we can find that new restaurant. Navigation is the science of following a planned path from one point to another. This includes using a GPS, or Global Positioning System, to navigate your car to a destination, guide a hiker through the woods, or help first responders locate you in an emergency. GPS is also used by financial institutions to timestamp transactions like the swipe of a credit card or a cash withdrawal from an ATM. Accurate timing is also necessary to support critical applications in space such as NASA's communication and tracking networks. [ Music ] NASA's Small Business Innovation and Research, or SBIR program, supports the development of technologies that benefit NASA, encourages private sector commercialization of innovations, and in turn provides spin-offs that improve our lives every day. SBIR program is very important to developing technology for NASA as it insulates NASA programs from the risks associated with the far reaching technology development. It also gives NASA access to the efficiencies and the capabilities of small businesses. The small business innovative research program develops technologies in three phases. In phase one, a six-month conceptual study is performed to determine feasibility of the idea. In phase two, a two-year hardware development or software development is undertaken. At the end of that time, a prototype is delivered for NASA. Phase three is when the prototype is incorporated or adopted by an internal NASA program or by a large American business for further development. Most US rocket launches take place along the US eastern launch range at either Kennedy Space Center or Cape Canaveral Air Force Base. In the event of a failure, the NASA range flight safety systems provides a means to prevent that launcher from reaching populated areas. Three, two-- As part of the effort to improve safety during launches, NASA is developing a system that uses Global Positioning System Receivers placed directly on-board the launch vehicle to track its trajectory during ascent. The SBIR program allows us to help guide outside expertise and exploring fundamental problems and interests that NASA has. We're looking at ways to mitigate possible interference of the GPS signals on a launch vehicle using commercial GPS receivers. So it usually involves antenna technology to look at multiple satellites and compare different signals and be able to cancel out any potential interference. The SBIR program funds a number of initiatives that support navigation from the time of launch throughout interplanetary transfer. These initiatives may one day help navigate spacecraft in deep space using x-ray and gamma ray pulsar based navigation. Pulsars are rapidly spinning stars, which broadcast a repeating signal. They are, in fact, lighthouses in the cosmos that can be used to help spacecraft navigate through space. We do have a success to talk about through the SBIR program and that is with x-ray navigation we have developed a catalog of pulsars that are good for our purposes, and we've also developed first generation algorithms to analyze the data. We are in the process of building instruments for x-ray navigation-- one to fly on the space station and perhaps elsewhere. One area where we have a gap in our knowledge is in onboard autonomous navigation. So we want to have pinpoint landings on various objects and when the round-trip light time becomes prohibitive, you want on-board autonomous nav. And that's an area of focus that we would like to delve into more. The SBIR also funds a number of technologies that support navigation once we reach the surface of other planets. There have been a number of successes in the SBIR subtopic for planetary surface navigation. In particular, there's been a phase two effort that's developed a GPS-like capability that, for surface planetary navigation position fixing that operates over ranges between one and say 10 kilometers. Here we have an example of a piece of hardware that could be deployed on a suit or perhaps a vehicle or, and would also be deployed on the fixed nodes on towers. This was developed as part of the phase two and delivered to us. There's also been successes in the areas of celestial navigation for planetary surface navigation as well as Bayesian filtering for surface navigation. The development of these cutting-edge mission-critical technologies not only help us navigate our way through deep space, they help us get to where we're going right here on earth. Turn left on second street. I'm not an expert on GPS's but it looks like Tim, we've arrived. Yeah, this place looks incredibly good. Well that was some of the best driving I've ever seen Bob. It's not quite as good as your flying of the space shuttle but- I try to do my best. So whether you swipe your ATM card, make a call on your cell phone, or try to find your way to a new restaurant, many of the advancements in communication and navigation technologies that we enjoy today started with technology developed in partnership with NASA. [Music]
History
Before NASA's administrator Michael D. Griffin created SCaN to direct an integrated networks program, different organizations at NASA Headquarters have managed the Agency's space communications capabilities and functions under separate Programs using a variety of administrative approaches.[2]
The SCaN Office was established by direction of Griffin in a Memorandum entitled "Establishment of a Space Communications and Navigation Office," dated July 19, 2006.[3] SCaN operates as a central organization within the Human Exploration and Operations Mission Directorate (HEOMD):
The Office's responsibilities encompass the management of existing space networks including the Tracking and Data Relay Satellite system, the Deep Space Network, the Ground Network, the NASA Integrated Services Network; implementing any improvements and upgrades to those systems and networks; and developing any future NASA communications and navigation architectures.
The Ground Network (GN) has since been renamed the Near Earth Network.
Services
SCaN is viewed as a service provider supporting interfaces and performing a standard set of functions, including:[4]
- Forward data transfer (uplink to spacecraft)
- Return data transfer (downlink from spacecraft to ground)
- Dissimilar voice communications
- Emergency communications
- Post-landing communications
- Radiometric measurement
- Time correlation
- Service monitoring
- Ephemeris exchange
- Operational coordination
- Service scheduling.
Communications schemes
Communications with spaceborne platforms is performed by RF, with a selection of spectra, modulation, and encoding methods, enumerated below.
Spectra
The Space Network communicates with spacecraft using S-band, Ku-band,[5] and Ka-band with planned laser/optical communications.
The Deep Space Network communicates with spacecraft using S-band, X-band, and Ka-band.
Modulation
SN uses phase-shift keying and phase modulation of the carrier signal.[6]
Encoding
The Space Network (used for near-Earth communications) supports the following encoding schemes:[7]
- BPSK
- QPSK/SQPSK
- 8PSK
- Rate 1/2 convolutional coding
- SQPN
- PRN coding - used to reduce power spectral density for low bit rate signals, and for time transfer.
The Reed–Solomon method is used as the initial error-correcting block code prior to the selected secondary encoding scheme.
See also
References
- ^ SCaN Testbed homepage at NASA Glenn Research Center
- ^ NASA. Space Communications and Navigation (SCaN) Program Plan. National Aeronautics and Space Administration.
- ^ NASA (January 30, 2009). SCaN Systems Engineering Management Plan (SEMP). NASA Space Communication and Navigation Program Office. SCaN-SEMP.
- ^ NASA (June 28, 2008). Constellation Design Reference Missions And Operational Concepts (ConOps), Annex 1: Constellation Communications and Tracking Concept of Operations (Baseline ed.). National Aeronautics and Space Administration. CxP 70007, ConOps.
- ^ NASA, Exploration and Space Communications Projects Division; Goddard Space Flight Center (August 2007). Space Network User's Guide (SNUG), 2.3, Elements of the SN (Rev 9 ed.). National Aeronautics and Space Administration. 450-SNUG.
- ^ NASA, Exploration and Space Communications Projects Division; Goddard Space Flight Center (August 2007). Space Network User's Guide (SNUG), 6.2 SSA Forward Services, and 6.2.3 Phase Modulation (PM) Signal Parameters (Rev 9 ed.). National Aeronautics and Space Administration. 450-SNUG.
- ^ NASA, Exploration and Space Communications Projects Division; Goddard Space Flight Center (August 2007). Space Network User's Guide (SNUGx) (Rev 9 ed.). National Aeronautics and Space Administration. 450-SNUG.
External links