Mars: What to expect on landing night

CALTECH (US) — NASA’s rover Curiosity is scheduled to land on the surface of the Red Planet on Sunday, August 5.

Curiosity should actually touch down around 10:17 p.m. PDT, but with nearly 14 minutes of radio-transmission time between Mars and Earth at the time of landing, mission control at the Jet Propulsion Laboratory (JPL) at Caltech does not expect to receive confirmation of the rover’s landing until 10:31 p.m. PDT at the earliest.

Want to be a witness to this historic landing? NASA TV coverage online begins August 5 at 8:30 p.m. Pacific/11:30 p.m. Eastern.

Museums, science centers, and NASA visitor centers around the country will be hosting viewing parties and events. The NASA TV coverage will even be broadcast on the Toshiba Vision screen in New York’s Times Square.

First several minutes

During its atmospheric entry, descent, and landing, the Mars Science Laboratory spacecraft will transmit simple signals called X-band tones (so named because they fall in the X-band portion of the radio spectrum).

For the first several minutes of the landing sequence, those tones will be picked up by the antennas of NASA’s Deep Space Network, and will thus reach Earth directly.

Part way through the hair-raising sequence, however, Earth will set below the Martian horizon, making it impossible to use the X-band tones for any further confirmation of the craft’s progress.

At that point, the focus will shift to the link between the MSL spacecraft and NASA’s Mars Odyssey orbiter, one of three satellites currently orbiting the planet. Odyssey is scheduled to receive transmissions from the spacecraft in the ultrahigh-frequency (UHF) portion of the radio spectrum beginning about two minutes after MSL enters the Martian atmosphere and continuing through its scheduled landing.

The orbiter will relay the information directly to Earth via X-band links. The Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express are also scheduled to receive transmissions from MSL during landing, but those orbiters will record the information and forward it to Earth hours later.

The first postlanding news conference at JPL is scheduled for no earlier than 11:15 p.m. PDT.

First Martian day

The day Curiosity touches down on Mars is designated the rover’s “sol 0.” (A sol is a Martian day, which lasts about 40 minutes longer than an Earth day.) After landing, Curiosity has several other tasks on its to-do list for sol 0: it will check its health and measure its tilt, fire all of its pyrotechnic devices (to trigger deployments such as the removal of dust covers from its hazard-avoidance cameras, or Hazcams), and take images with its front and rear Hazcams.

The mission team says that it is “possible but unlikely” that we will get to see one or more of those first images on landing night.

Indeed, it may be days or weeks until full video footage of the landing from the spacecraft’s perspective will be available for viewing. That footage will come from one of Curiosity’s 10 scientific instruments, the Mars Descent Imager, which will record full-color video of the ground below as Curiosity descends to the surface, shooting at about four frames per second with close to 1,600 by 1,200 pixels per frame.

Thumbnails and a few samples of the full-resolution frames are expected to reach Earth in the first few days after landing.

By the end of the night on Sunday (PDT), we should know whether Curiosity touched down safely on Mars, we might get the first images from the parked rover, and we will be looking forward to receiving much more information in the days, weeks, and months ahead.

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