NASA’s Mars Reconnaissance Orbiter reached the red planet in March 2006, and entered into a highly elliptical orbit– the type of orbit easiest to achieve in that it requires the least amount of fuel to enter. MRO is pretty big, about the size of a bus, so fuel was at a premium.
The probe’s orbit had to be lowered to get it into position to be able to map mars. To do this, the low point in the orbit was manipulated using on-board rockets to dip the probe into the upper part of the martian atmosphere, a maneuver called aerobraking. This idea was used in the movie "2010" to get the Leonov into a Jupiter orbit. In the movie, the effect was very dramatic and scary. In real life, MRO only dipped its toes into the air, so to speak, slowing itself gently every time it reached its closest approach to Mars. This changed the shape of the orbit, lowering it and making it more circular.
And now, finally, on September 11, MRO’s orbit is where it needs to be to start the science! Initially, the high point of the orbit was 45,000 km over Mars’ surface, but now it’s at 486 km. Imagine– at first, the orbits were very long, and the aerobraking maneuvers took place over a day apart. But as the orbit changed, and got smaller and shorter in period, the maneuvers got closer and closer together in time. Eventually they were every two hours! it’s hard to imagine the nightmare it must have been to watch over that, and how exhausting it would have been… and so once again we see that the heroic efforts of the JPL teams have paid off.
Now the detailed work begins. The delicate instruments on-board the probe need to be switched on, tested, and unleashed. The most exciting one is arguably HiRISE, a very high-resolution camera that will be able to see objects as small as a meter across on the surface of Mars! The images will be incredible. I can’t wait– but I’ll have to, since it’ll be the end of the month before we start to see those images. Stay tuned here as usual, and I’ll post ‘em as I get ‘em.
Image credit: NASA/JPL
September 13th, 2006 at 1:42 pm
I didn’t know that MRO was as large as a bus. Isn’t that about the size of Cassini too? Least the large class of probes aren’t dead.
Anyway, it’ll be facinating to see what MRO turns up on Mars.
Might it be possible for the probe to spot the MERs, Vikings, and Pathfinder probes?
September 13th, 2006 at 2:17 pm
If I was in charge at JPL, I would make the first target the Cydonia region (the face on Mars) just to shut up Richard c. Hoagland!!!
September 13th, 2006 at 2:20 pm
“Might it be possible for the probe to spot the MERs, Vikings, and Pathfinder probes?”
Actually I was thinking along the lines of Beagles and Polar Landers (both AWOL).
September 13th, 2006 at 2:21 pm
You know that wouldn’t make Hoagie shut up.
As I recall, the long-range shots from HiRISE were incredible. I’m similarly impatient to see some of the close-range stuff. This is SO cool.
September 13th, 2006 at 2:36 pm
I too can hardly wait for the ‘good stuff’ to start showing up. I expect that this is gonna be incredible!
September 13th, 2006 at 2:55 pm
The size of a bus, huh?
Size I enjoy crashes I have to ask: How big was the probe that they crashed on the moon last week? And will they be crashing this one into mars?
September 13th, 2006 at 9:58 pm
Of course, the HBs will be crying foul that nobody has sent cameras with one-meter resolution to image the Apollo landing sites on Earth’s moon.
Anyway, looking forward to even more spectacular views of Mars in the months ahead!
September 13th, 2006 at 10:53 pm
When they were done with the aerobraking, they would have had to do a circularizing burn at the new apogee or else the perigee (uh, perimars? periares?) would stay within the atmosphere until the whole thing came down. How much fuel do they have remaining to do orbital maintenance? That is usually the limiting factor in an orbiting probe.
- Jack
September 14th, 2006 at 2:44 am
If that thing is the size of a bus, what happens if it finds something the size of a bus stop? And if someone is waiting there??
Ivan.
September 14th, 2006 at 3:53 am
“Of course, the HBs will be crying foul that nobody has sent cameras with one-meter resolution to image the Apollo landing sites on Earth’s moon.”
Yep, it indicates that mankind is more interested with Mars (actually 4 orbiters, 2 rovers, with more to come) than our nearby Moon. With Vision, this will change. For example, future LRO mission can spot largest artifical structures left on Moon by man.
September 14th, 2006 at 4:21 am
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You know that wouldn’t make Hoagie shut up.
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Yeah, I know. He’d probably say that JPL “doctored” the images before releasing them.
September 14th, 2006 at 5:52 am
Finally we wil lget hi-res pics of the Martian cities!!!
/just kidding, folks
September 14th, 2006 at 6:27 am
So now whats our total number of man-made objects that have been sent to Mars? That number seems to be climbing quite a bit lately.
September 14th, 2006 at 7:54 am
HiRes? At one meter? So how come our spy sats can read the image of a license plate but we can’t get such in orbit of MArs? Hardly seems fair that we spend so much keeping an eye on problem folks on earth, but can’t send that tech. to a major planet.
My idea of hi res is being able to read the numbers on your pocket calculator from orbit.
GAry 7
September 14th, 2006 at 11:15 am
“…My idea of hi res is being able to read the numbers on your pocket calculator from orbit…”
Then JPL would have to prepare a separate mission to send the pocket calculator down to Mars.
September 14th, 2006 at 11:21 am
Note to GAry 7…
From what I’ve read, our spy sats *CAN’T* read the image of a license plate; you need an SR-71 for that. Spy sats have resolution primarily limited by the size of atmospheric convection cells, about 4 – 6″. To get something like this at Mars, you’d need to send something about the size / mass of Hubble — WAY too heavy to send there, given current technology.
As for MRO, it about has the best resolution we can make use of, given limitations of the current DSN. Mind you, resolution doesn’t do you much good if you can’t get the pictures back. As a result, a trade that has to be made is resolution vs. coveerage. Even at MRO’s resolution (a lot better than for previous birds, but nowhere near 6″), bandwidth limitations mean that MRO can only image 2% of the surface of Mars at full resolution in its 5 year nominal lifespan.
Future missions will be able to send vastly more data back, once spacecraft are flying (and DSN is supporting) laser communications, but with the current state of RF technology, this is the best that can be done.
Lorne
September 14th, 2006 at 11:37 am
“Then JPL would have to prepare a separate mission to send the pocket calculator down to Mars.” Yeah, O.K. I’d be the “your” attached to the pocket calculator. For shure.
September 14th, 2006 at 2:33 pm
I was thinking, I want to see those glass worms at 1m res!
September 14th, 2006 at 6:09 pm
A few years back they actually did acheive better resolution images of the ‘face’ on mars…turns out the face looks more like a butte! Of course Hoagland prefers the lower resolution images; there’s always some way to see exactly what you want to see. I don’t have a link but should be easy to find on the internet.
September 14th, 2006 at 8:18 pm
Actually, I think there’s an entry or two about that right here at Bad Astronomy!
http://www.badastronomy.com/bad/misc/hoagland/face.html
September 15th, 2006 at 11:43 pm
The Lunar Reconnaissance Orbiter Camera (LROC) consists of 2 narrow angle camera heads (NACs) to provide 0.5 m-scale panchromatic images over a 5-km swath, a wide angle camera head (WAC) to provide images at a scale of 100 m in seven color bands, and a common Sequence and Compressor System (SCS) to sequence image acquisition by all camera heads and compress their data before transmission to the spacecraft.
I don’t know what Panchromatic means, but it looks like LRO will be able to image the S-IVB’s and LEM descent stages on the moon.