This story was originally published by U.S. NASA Space Agency:

This story was originally published by U.S. NASA Space Agency:
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The Mars Relay Network Connects Us to NASA’s Martian Explorers

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Over the Horizon

As Perseverance enters the Martian atmosphere inside its protective aeroshell, the rover will switch between several of its onboard antennas to stay in contact with Earth. Some of these antennas use powerful X-band transmissions that can send small amounts of data directly to the DSN. Others use ultra high frequencies (or UHF) to communicate with MRO and MAVEN.

Managed by JPL for NASA’s Space Communications and Navigation program (SCaN), the DSN consists of several parabolic radio antennas at ground stations in Southern California, near Madrid, Spain, and outside Canberra, Australia. This configuration allows mission controllers to communicate with spacecraft throughout the solar system at all times throughout Earth’s daily rotation. During Perseverance’s landing, Madrid’s antennas will be trained on Mars, taking the lead when receiving data. The Goldstone complex near Barstow, California, will also be listening in as a backup.

Since the landing of NASA’s Mars Exploration Rovers Spirit and Opportunity in 2004, science data has been routinely relayed via the Mars orbiters to the DSN, beginning with MGS and then NASA’s veteran Odyssey orbiter, which has been circling Mars since 2001.

Because the final two minutes of Perseverance’s descent and landing will be mostly beyond Mars’ horizon from Earth’s perspective, “direct-to-Earth” X-band communications will be impossible, and the rover will communicate with Earth solely via MRO and MAVEN when it lands.

In orbit since 2006, MRO was designed as a science mission and to act as a communications relay for landed surface missions. But it received an upgrade to prepare for Perseverance’s landing.

“In the past year, the software of the MRO spacecraft and its UHF radio have been updated to allow the near-immediate return of data collected during EDL. MRO will capture the telemetry transmitted by Perseverance and use its 3-meter [10-foot] dish to transmit it immediately to Earth,” said Roy Gladden, manager of the Mars Relay Network at JPL. “We call this a ‘bent pipe’, which allows us to get word from Perseverance even though Mars is blocking our view from Earth.”

First Word From Jezero

As MRO relays Perseverance’s landing in near-real-time, engineers in mission control hope to confirm landing – and receive the first image – soon after 12:55 p.m. PST (3:55 p.m. EST). Because of the distance the signal has to travel from Mars to Earth, the spacecraft will have landed (known as “spacecraft event time”) 11 minutes and 22 seconds earlier.

Later, at about 4:27 p.m. PST (7:27 p.m. EST), Odyssey will fly over the landing site and communicate with the rover to confirm its health. The next relay session after that will be at about 6:36 p.m. PST (9:36 p.m. EST) by ESA’s (the European Space Agency’s) Trace Gas Orbiter (TGO), which will also check in on Perseverance’s health and relay any images the rover has transmitted from the landing site.

In addition, MAVEN will capture the entire landing with a data-rich broad spectrum recording, and will send the information back to Earth several hours after landing. This data could be used to fill in any telemetry (engineering data) from the rover during EDL that was missed by MRO during the initial relay, and provide other measurements of the event.

This buddy system helps ensure that little data is lost during Perseverance’s historic landing in Jezero Crater while also confirming the health of the rover and its precise location.

[1] Url: https://www.jpl.nasa.gov/news/the-mars-relay-network-connects-us-to-nasas-martian-explorers

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