[MikeHOU]

The next rover to explore Mars, named Curiosity, is nearing Mars.

Here is a snapshot of the current trajectory:



Landing is scheduled for August 5.

Source: YouTube

It should be a very exciting two year mission to study the region around Gale Crater for evidence of microbial life.

Source: YouTube

[Nancy]

The next rover to explore Mars, named Curiosity, is nearing Mars.

Which is it? Is it the laboratory one?

[donnah]

Very exciting. Thanks for posting that Mike.

[MikeHOU]

Originally Posted by Nancy

Which is it? Is it the laboratory one?

Yes, Nancy, that's the one:

Mars Science Laboratory

[Margo]

Thanks for the pics, very interesting.

[Nancy]

bump

[MikeHOU]

Since I linked my very first image to the NASA web site, it is current as of now.

[ARIES3032]

Thank you Mike for this information. It is exciting!!

[Gregory]

That's really cool. So much they can learn about Mars.

[MikeHOU]

It is really cool stuff.

Being a trajectory guy it's interesting to note that we can't go to Mars anytime we want.

Because of the orbits of the earth and Mars about the sun, opportunities for a minimum energy trajectory (what is known as a Hohmann transfer) only occur about every 2 years and is based on the synodic period.

Lets say that Mars is at it's closest point to the Earth. Because the earth orbits the sun in one year and Mars takes 1.88 years, they will move away from each other. The synodic period is the amount of time it would take Mars to return to it's closest point to earth. The formula is pretty simple:

S = 1/(1 - 1/1.88) = 2.14 years

The period for minimum energy (and thus minimum fuel) launches is called the launch window. Curiosity was launched during the window that opened in November of 2011. The next window won't occur until December 2013. If you launch outside the window you will need a much larger launch vehicle will lots and lots more fuel.

[MikeHOU]

Since shortly after leaving earth the spacecraft has been traveling basically under the influence of only the sun's gravity.

When it gets within a distance of about 170 Mars radii (577,000 km or 359,000 miles) the gravitational tug from Mars will be about equal to that of the sun. And as the spacecraft gets closer the gravity well of Mars will increase and so will the speed of the spacecraft.

Relative to the sun the orbit at this point is still an ellipse, but relative to Mars it is on a hyperbola. So, if nothing is done, the spacecraft would leave Mars as fast as it arrived. However, the spacecraft will use it's rockets to slow down the trajectory such that it will enter the Martian atmosphere.

The angle of entry at the top of the atmosphere is critical. If the angle is too shallow it will skip off and the mission is probably a failure. If the angle is too steep it will exceed heating loads and be coming in too fast for a successful landing.

Everything has to be just right which makes it all very exciting!

[MikeHOU]

This will happen about a month from now:

Source: YouTube

For me this is very exciting stuff - exploration at its best.

[Nancy]

Relative to the sun the orbit at this point is still an ellipse, but relative to Mars it is on a hyperbola. So, if nothing is done, the spacecraft would leave Mars as fast as it arrived. However, the spacecraft will use it's rockets to slow down the trajectory such that it will enter the Martian atmosphere.

I really wish I could understand all of this. It's a different language for me.

[MikeHOU]

Happening later this week:

Source: YouTube

[MikeHOU]

Originally Posted by Nancy

I really wish I could understand all of this. It's a different language for me.

Let me try to make it clearer.

Mars (like all the planets) travels in an orbit about the sun that is an ellipse. For most of its journey the spacecraft is under the gravitational influence of predominantly the sun and it is trying to rendezvous with Mars.

At a certain distance close to Mars called the sphere of influence (SOI), the gravitational tug from Mars equals that from the sun. At that point the predominant force is now Mars but because the vehicle is traveling so fast the path it follows relative to Mars is a hyperbola. This means that if nothing is done the vehicle will leave the Mars SOI as fast as it entered - back out to a region predominantly influenced by the sun's gravity again.

So, what they do is turn on the engines to slow the speed down. At some point the speed becomes slow enough that the hyperbolic trajectory becomes an elliptical trajectory. At that point the vehicle has been captured by Mars!

I hope this helps.

[voice1]

Good luck tonight with the landing. Very exciting.

[Ace917]

CURIOSITY HAS LANDED !!

[Nancy]

WOO HOOOOOOO

USA USA USA

[Nick_Bradley78]

As Obama said, an amazing feat of technology, a million things needed to work....and they did. Nice job.

[Keith]

It slowed down with the help of a supersonic parachute before an elaborate sky crane powered by rocket blasters kicked in and, in a technological first, the rover - the size of a Mini - was lowered with nylon cables into a giant crater.

"Touchdown confirmed," said engineer Allen Chen. "We're safe on Mars."

That is a seriously impressive piece of kit!

Nice to wake up and read this sort of news for a change - very exciting stuff.