Speaking Percy's Language: How to Talk so Perseverance Will Listen
Perseverance's Selfie: NASA’s Perseverance Mars rover took a selfie with the Ingenuity helicopter. This image was taken by the WATSON camera on the rover’s robotic arm on April 6, 2021, the 46th Martian day, or sol, of the mission. Credits: NASA/JPL-Caltech/MSSS. Download image ›

If you’ve ever watched a basketball game, you might have seen a lucky fan be brought out to half court and given one chance to sink a basket – if they do, a grand prize awaits them. Most of the time they miss. But every so often, miracles happen.

The large antennas of NASA's Deep Space Network provide two-way communications with spacecraft at Mars and other bodies in the solar system.
Deep Space Network antennas at Goldstone's "Apollo Valley": Antennas of NASA's Deep Space Network provide two-way communications with spacecraft exploring the planets. Credits: NASA/JPL-Caltech. Download image ›
At JPL, we have to achieve a minor miracle every day. Sending commands to the Perseverance rover is a bit like sinking that half-court shot, but much harder: we need to get a signal all the way from Earth to Mars, which can be as far as 250 million miles away. The Deep Space Network (DSN) is a corner stone NASA infrastructure made up of giant 34m and 70m diameter antennas in California, Australia and Spain that enables radio communication with spacecraft at these incredible distances.

At the end of each and every operations shift, the engineering team reviews the day’s commanding strategy. After making sure that we’ve included all of our expected commands for the rover, we review exactly how we will get these commands to Mars. This is done in the form of a creating and reviewing a “Radsheet,” or Radiation sheet, which contains instructions on exactly how and when to send our commands to the rover. This is how we make the miracle of sinking the half-court shot to Mars happen every day.

Cropped photo showing the rover’s 3 antennas, with the HGA in the front (the hexagonal paddle).
Perseverance's Selfie: Cropped photo showing the rover’s 3 antennas, with the HGA in the front (the hexagonal paddle). Credits: NASA/JPL-Caltech/MSSS. Download image ›
Perhaps the most important information in the Radsheet are the exact times that each set of commands should be sent to Mars. These times are a culmination of known events: commanding the rover can only happen using reserved time on a Deep Space Network (DSN) antenna, which must be pointed in the direction of Mars at the exact moment that Perseverance wakes up and points its High Gain Antenna towards Earth to listen for our daily instruction. Synchronizing these events is further complicated by the time it takes for commands to reach Mars. Although radio waves travel at the speed of light, Earth and Mars are so far apart that it takes between 3 and 22 minutes for commands to reach Perseverance depending on where Mars and Earth are in their orbits around the Sun.

What marks the end of operations shift is when the Radsheet is provided to the Mars2020 Ace, the mission controller responsible for sending commands to Mars from the JPL space flight operations facility through the DSN. After a long day of planning, the operations team celebrates this by a tradition of hitting the gong that sits in our operations room!

Communication engineers at NASA’s Jet Propulsion Laboratory
Monitoring Spacecraft: Communication engineers at the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory in Southern California. Credits: NASA/JPL-Caltech. Download image ›

About This Blog

These blog updates are provided by self-selected Mars 2020 mission team members who love to share what Perseverance is doing with the public.

Dates of planned rover activities described in these blogs are subject to change due to a variety of factors related to the Martian environment, communication relays and rover status.

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  • Mariah Baker
    Planetary Scientist, Smithsonian National Air & Space Museum
    Washington, DC
  • Iona Brockie
    Sampling Engineer, NASA/JPL
    Pasadena, CA
  • Sawyer Brooks
    Docking Systems Engineer, NASA/JPL
    Pasadena, CA
  • Adrian Brown
    Deputy Program Scientist, NASA HQ
    Washington, DC
  • Denise Buckner
    Student Collaborator, University of Florida
    Gainesville, FL
  • Fred Calef III
    Mapping Specialist, NASA/JPL
    Pasadena, CA
  • Alyssa Deardorff
    Systems Engineer, NASA/JPL
    Pasadena, CA
  • Kenneth Farley
    Project Scientist, Caltech
    Pasadena, CA
  • Brad Garczynski
    Student Collaborator, Purdue University
    West Lafayette, IN
  • Erin Gibbons
    Student Collaborator, McGill University
    Montreal, Canada
  • Louise Jandura
    Chief Engineer for Sampling & Caching, NASA/JPL
    Pasadena, CA
  • Lydia Kivrak
    Student Collaborator, University of Florida
    Gainesville, FL
  • Rachel Kronyak
    Systems Engineer, NASA/JPL
    Pasadena, CA
  • Matt Muszynski
    Vehicle Systems Engineer, NASA/JPL
    Pasadena, CA
  • Pegah Pashai
    Vehicle Systems Engineer Lead, NASA/JPL
    Pasadena, CA
  • David Pedersen
    Co-Investigator, PIXL Instrument, Technical University of Denmark (DTU)
    Copenhagen, Denmark
  • Vivian Sun
    Science Operations Systems Engineer, Staff Scientist, NASA/JPL
    Pasadena, CA
  • Jennifer Trosper
    Project Manager, NASA/JPL
    Pasadena, CA
  • Roger Wiens
    Principal Investigator, SuperCam / Co-Investigator, SHERLOC instrument, LANL
    Los Alamos, NM

Tools on the Perseverance Rover+

The Perseverance rover has tools to study the history of its landing site, seek signs of ancient life, collect rock and soil samples, and help prepare for human exploration of Mars. The rover carries:


Where is the Rover?

Image of a rover pin-point at Perseverance's location on Mars, Jezero Crater

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