How does nasa communicate with the mars rovers

It generally takes about 5 to 20 minutes for a radio signal to travel the distance between Mars and Earth, depending on planet positions.

The mass- and power-constrained rover can achieve high data rates of up to 2 megabits per second on the relatively short-distance relay link to the orbiters overhead. The orbiters then use their much larger antennas and transmitters to relay that data on the long-distance link back to Earth.

The X-Band High-Gain Antenna The high-gain antenna is steerable so it can point its radio beam in a specific direction. This distance is accurate to about five to ten meters feet , even though the spacecraft may be billion meters away! Delta DOR is similar to ranging, but it also takes in a third signal from a naturally occurring radio source in space, such as a quasar, and this additional source helps scientists and engineers gain a more accurate location of the spacecraft.

Quasars are a few billion light years away and a few billion years in the past. Quasars are used as extremely well known positions in the sky to provide a calibration for the same measurements made within a few tens of minutes of each other on a spacecraft. Being able to do quasar and spacecraft ranging near the same time and subtracting the answers cancels a lot of errors that are the same in both measurements from the atmosphere and the equipment.

The "ranging" is not really ranging, but differenced ranging. What is measured is the difference in the distance to the source between two complexes on Earth for example, Goldstone and Madrid or Goldstone and Canberra.

From that an angle in the sky can be determined relative to the stations. The angle for the quasar is subtracted from the angle of the spacecraft, giving the angular separation of the quasar and the spacecraft.

That angle is accurate to about five to ten nanoradians, which means when the spacecraft is near Mars, say million kilometers away, it can determine the position of the spacecraft to within one kilometer 0. During the entry, descent and landing phase of the Mars Exploration Rover mission, engineers listened anxiously for distinct tones that indicated when steps in the process were activated; one sound indicated the parachute deployed, while another signaled that the airbags had inflated.

These sounds were a series of basic, special individual radio tones. The Mars Science Laboratory spacecraft transmitted in X-band during its entry, descent and landing process, which was the expected path for confirmation of the initial events in the process.

Due to signal strength constraints, these transmissions were simple tones, comparable to semaphore codes, rather than full telemetry. The Deep Space Network listened for these direct-to-Earth transmissions. By then, the bent-pipe relay via Odyssey had begun.

Not only does the rover send messages directly to the DSN stations, but it is also able to uplink information to other spacecraft orbiting Mars, utilizing mainly the Mars Reconnaissance Orbiter and Mars Odyssey if necessary spacecraft as messengers that pass along news to Earth for the rover.

The respective spacecraft mainly "talk" via their UHF antennas. These specifications split the baseband unit, which is responsible for processing and transferring data to or from the core network, into two smaller components.

One component is the distributed unit, which takes over the data-processing responsibilities. The other component is the centralized unit, which handles the connection to the core network. The advantage of splitting the baseband unit in this way is that the centralized unit no longer needs to be located at the cell tower itself. Instead, a single centralized unit can sit in a local server farm, maintaining the connection to the core network for multiple cell towers in the area. Each of these additional splits creates a division somewhere amid the many steps between a signal's arrival from the core network and its transmission to a cellphone.

It's a bit like taking a lunch break: You can take an early lunch and thus shift many of your responsibilities to the afternoon, or work for several hours before opting for a later lunch. One important split, called Split 7. On the other side of the split, the radio is responsible for some light processing duties like beamforming, which establishes the specific direction of a transmission. The radio is also still responsible for converting digital signals to analog signals and vice versa.

Another split, Split 8, shifts even the responsibility for beamforming to the distributed unit, leaving the radio responsible only for converting signals. In contrast, Split 2 would push encoding, decoding, modulation, beamforming, and even more processing responsibilities to the radio, leaving the distributed unit responsible only for compressing data to a smaller number of bits before transferring the data to the centralized unit.

The goal in creating open standards for multiple kinds of splits is that operators can then purchase better-tailored components for the specific kind of network they're building. For example, an operator might opt for Split 8 for a large-scale deployment requiring a lot of radios. It's technically possible to put together a disaggregated RAN with open interfaces using only hardware, but defining the components in software has some advantages.

So every time we need to have an upgrade, or new release, or new fractional release, it takes years. In order to move away from a hardware-centric attitude, the O-RAN Alliance is also encouraging the wireless industry to incorporate more software into the RAN. Software-defined networks, which replace traditional hardware components with programmable software equivalents, are more flexible.

Upgrading a virtual component can be as simple as pushing out new code to the base station. The emphasis on software is also making it possible for the industry to consider entirely new technologies, the most important of which is the RAN Intelligent Controller. The RIC collects data from the RAN components of dozens or hundreds of base stations at once and uses machine-learning techniques to reconfigure network operations in real time.

It bases the modifications on whether particular cell towers are under a heavy traffic load, for example, or transmitting in a heavy rainstorm that might dampen signals. Since its founding in , the O-RAN Alliance has ballooned from its five founding members—all operators—to more than members.

Of the big three vendors, only Huawei is not a member, citing its belief that Open RAN systems cannot perform as well as the company's proprietary systems. Other Open RAN groups are growing at a similar pace. Rakuten's engineers can install a 4G base station for its Open RAN deployment in as little as 8 minutes. After a mandate from the British government to strip all Huawei components from wireless networks, England-based Vodafone is replacing those components in its own networks with Open RAN equivalents.

Because of similar mandates, local operators in the United States, such as Idaho-based Inland Cellular , are doing the same. These deployments haven't always gone as planned. Rakuten, in particular, faced some initial setbacks when its Open RAN network's performance didn't match the performance of a traditional end-to-end system.

The operator remains optimistic, however, and hasn't given up on it. Many in the industry aren't concerned about these kinds of issues, arguing that the only way to actually iron out the wrinkles in the technology is to deploy it at scale and see what works and what needs improvement. There are also still lingering questions over where the buck stops. When an operator buys an end-to-end system from Nokia or Ericsson or Huawei, it also knows it can depend on that vendor to support the network when problems crop up.

Not so with Open RAN deployments, where no single vendor is likely to claim responsibility for interoperability issues. Larger operators will likely be able to support their own Open RAN networks, but smaller operators may be reliant on companies like Mavenir, which have positioned themselves as system integrators.

Critics, however, see that approach as just creating another kind of end-to-end vendor—and adding additional expense—for operators that don't have the expertise or resources to support their own networks. In the end, Open RAN's true test may come when it's time to implement the next generation of wireless.

It remains to be seen how far the movement will go to disaggregate the RAN, to open up new interfaces, or even to bring new technologies into the mix. What's important is that the movement has already gained substantial momentum. Even though some corners of the industry still have reservations, operators and small-scale vendors have put too much weight behind the idea for the movement to fizzle out.

Open RAN is here to stay. As it matures, the wireless industry will be open for a new way of doing business. Explore by topic. The Magazine The Institute. IEEE Spectrum. Our articles, podcasts, and infographics inform our readers about developments in technology, engineering, and science. Join IEEE. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Enjoy more free content and benefits by creating an account Create an account to access more content and features on IEEE Spectrum, including the ability to save articles to read later , download Spectrum Collections , and participate in conversations with readers and editors.

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Besides the Mars missions, the Deep Space Network also tracks missions headed toward Saturn, comets and asteroids, so the astronomers have to do some careful scheduling to ensure that spacecraft don't get busy signals. Once on Earth, the data is transmitted to the Jet Propulsion Laboratory in Pasadena, California, and then distributed to science teams around the world.

As of Feb. Only 18 percent of that data was transmitted directly to Earth; the rest was sent through the Mars Odyssey and Mars Global Surveyor relays.

The intra-Mars wireless network has an additional node in orbit. Europe's Mars Express also has a UHF relay, and it was tested with Spirit to verify that the international spacecraft could communicate with each other, providing an additional path back to Earth.