Mars Exploration Rover Mission

JPL ^ | 1-3-04 | JPL

[bonesmccoy]

Mission Timeline: Entry, Descent, and Landing

The entry, descent, and landing (EDL) phase begins when the spacecraft reaches the Mars atmospheric entry interface point (3522.2 kilometers or about 2,113 miles from the center of Mars) and ends with the lander on the surface of Mars in a safe state.

The rovers will arrive during the latter half of the northern winter/southern summer on Mars. Rover A will land at approximately 2:00 p.m. local time on Mars (with Earth set an hour after landing), whereas Rover B will land at around 1:15 p.m. local time on Mars (with Earth set as long as two-and-a-half hours after landing). That means that both rovers will land in the Martian afternoon while the Earth is still in view, allowing the Earth to receive the landing signal if the lander is on the base petal.

Entry, descent, and landing for the Mars Exploration Rover mission is an adaptation of the Mars Pathfinder method:

An aeroshell and a parachute decelerate the lander through the Martian atmosphere.

Prior to surface impact, retro-rockets are fired to slow the lander´s speed of descent, and airbags are inflated to cushion the lander at surface impact.

After its initial impact, the lander bounces along the Martian surface until it rolls to a stop.

The airbags are then deflated and retracted, and the lander petals and rover egress aids are deployed.

Once the petals have opened, the rover deploys its solar arrays, and places the system in a safe state. Communications during entry, descent, and landing will occur through a pair of low-gain antennas, one mounted on the backshell and the other on the rover itself. About 36 ten-second radio tones will be transmitted to Earth during descent through the atmosphere, which takes approximately six minutes. These tones are coded to indicate the accomplishment of critical steps in the entry, descent,and landing timeline. [More on these tones in the communications section]

A step-by-step guide to everything that will happen will be provided prior to entry, descent, and landing.

[bonesmccoy]

The aeroshell protects the rover from fiery temperatures as it enters the Martian atmosphere in January, 2004.

____________

With the parachute deployed, three retrorockets fire their engines, suspending the lander 30 - 50 feet above the Martian surface.

____________

Protected by large airbags, the lander falls away from the parachute, landing safely on Mars.

__________________

After bouncing to a stop, the lander's petals unfold and the Mars Exploration Rover drives onto the surface of Mars.

Good luck guys!

For a great on-line video of what this vehicle has to do in the next 24 hours, please visit this link:

http://marsrovers.jpl.nasa.gov/gallery/video/movies/mer_ch_edl_TerrorComb.mpg

Entry, Descent, and Landing Navigators must safely maneuver Spirit and Opportunity to their precise atmospheric entry points to reach their landing targets on the surface of Mars. In only six minutes, the spacecraft must slow down from an incredible speed of 12,000 mph to nearly zero. In this three-part episode of "The Challenges of Getting to Mars," spacecraft engineers give a play-by-play of the Entry, Decent, and Landing mission phase that they refer to as their nailbiting "Six Minutes of Terror."

Impact to Egress Even after the landers and airbags safely bounce to a complete stop on Mars, the challenges of getting to Mars continue. It will take each rover a minimum of nine days to emerge from its lander cocoon, stand up, orient itself, safely unlock its body from the lander, and roll down to the martian ground. In this last episode of the Challenges of Getting to Mars video series, the rover team describes the Impact to Egress phase of getting six wheels on the surface.

http://marsrovers.jpl.nasa.gov/gallery/video/movies/mer_ch_egress_part1.mpg

http://marsrovers.jpl.nasa.gov/gallery/video/movies/mer_ch_egress_part2.mpg

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[Howlin]

I cannot help it, bones; I am compelled to post this cartoon!

[CasearianDaoist]

I am so pumped about this mission - I sure hope it goes well.

[glock rocks]

I cannot help it, bones; I am compelled to post this cartoon!

I was thinking the same thing, Howlin ...

[leadpenny]

Thanks for posting. I'm sure NASA-TV is carrying this. Yesterday when I called Comcast and asked why they had dropped the channel some months ago, I was met with silence. I might as well have said I was from Mars.

[bonesmccoy]

Given the number of failed missions over Mars, don't laugh.

Back a few years, there was considerable discussion of the gremlins on Mars.

Gremlins seem to popup at the worst time and in the worst way during Mars missions.

The international community sent a flotilla of spacecraft to Mars during this launch opportunity. The Japanese and the British lost their spacecraft.

Now, JPL is holding all the cards for the entire international scientific community.

They need alot of luck in the next few hours to get the rover on the surface safely.

[bonesmccoy]

Good point... I'll check on line and see. brb

[NormsRevenge]

Thanks for the thread and 'toons!

Touchdown 8:35 PM PT tonight 1/3/04

[Howlin]

I am anxiously awaiting the landing!

[bonesmccoy]

looks like a conference is being webcast where a teacher is discussing space station.

[Howlin]

GUFFAW........I forgot about that!

[Howlin]

Can you catch the live streaming on the internet?

[InvisibleChurch]

Go USA!

[bonesmccoy]

It's important for freepers to understand that there will not be immediate confirmation of landing.

A delay of about 10 minutes will exist in the timing of the communication because of the distance between the two planets.

In addition, if the lander is not aligned correctly, the antenna could be blocked. If the lander does not land on it's base, it will need to rotate during the deployment of the petals.

I'm not an engineer on this mission, but with all of the gears and motors involved, you have to worry about a single point of failure screwing up the entire mission.

[Phil V.]

Just stoppit!

Yer wastin' bandwidth.

[leadpenny]

Thanks, I'll try the web.

[blam]

"Touchdown 8:35 PM PT tonight 1/3/04"

Yup. Fox News just announced landing time is 5:35PM EST this evening. Good Luck.

[Howlin]

What's the matter with you? I have a GOD GIVEN RIGHT to post on this forum and use all the bandwidth I want to! (Even though Free Republic and/or bandwidth isn't mentioned in the United States Constitution, as we all know!) :-)

[Howlin]

Oh, it's 5:30 our time? Glad you pointed that out! I would have missed it!