Curiosity on its way to Mars!

By Phil Plait | November 27, 2011 7:05 am

Yesterday morning, NASA successfully launched the Mars Science Laboratory — named Curiosity — toward the fourth planet. If, like me, you missed the launch itself (^%$#@&! sinuses) why then, here’s some pretty dramatic video of the liftoff:

[Make sure to set it to 720p resolution!]

The cool parts to watch are: about 2 minutes in when the booster rockets fall by the wayside; 3:42 when the payload fairing is jettisoned, exposing the Curiosity spacecraft — as seen by the camera onboard the rocket, which is way cool; 4:38 when the entire rocket starts to slowly spin up, providing stabilization and allowing the Sun to heat the assembly evenly; then a few seconds later when the upper stage Centaur rocket ignites, leaving the booster behind (also extremely cool).

But wait! There’s more!

There’s also a video taken a few minutes later, showing the view from the Centaur stage as the Curiosity spacecraft separates, a crucial moment in the mission. The Centaur is what boosted the spacecraft up to speed, putting it on the right trajectory to Mars.

I love that we can get video like this now!

As of right now, the spacecraft is headed toward Mars. Tucked away inside is the rover, but there’s also a heat shield to protect it as it enters the Martian atmosphere, and a rocket that will slow its descent even more… but why describe it when there’s another video that shows you what will happen:

The beginning of the video may help you make sense of the second video, too, since of course we don’t get that great third-person view from cameras on board the rocket. There’s a longer version of this video (11 minutes) with no narration, as well.

I’ve heard some folks wondering why NASA is using such a crazy complicated way to land the rover. The reason has to do with the gravity and atmosphere of Mars, as well as the mass of the rover itself. Landing on Mars is difficult. It has just enough gravity to make it hard to land with just rockets; it would take a lot of fuel, and that means you have to lug that all the way there, which in turn means less mass available for the science package. Mars also has air, which means you can use parachutes, but the air is too thin to make it practical to use them all the way down like we do on Earth. So we’re stuck having to use both rockets and parachutes.

And if you think Curiosity’s landing is crazy, don’t forget that Spirit and Opportunity used giant airbags to literally bounce their way down to the surface! That method wouldn’t work with Curiosity, which is too big for airbags.

My congratulations to everyone on the Curiosity team for a successful launch. Now we just have to sit back and wait 8+ months for it to reach Mars… and then the fun really begins.

CATEGORIZED UNDER: Cool stuff, NASA, Space
MORE ABOUT: Curiosity, Mars

Comments (78)

  1. Chris

    Somehow airbags don’t seem so crazy after seeing the Curiosity landing. I’m sure they checked and tested their landing system to the nth degree, but still I’m going to be very nervous next August.

  2. Patrick

    I couldn’t help but notice, in the third video, that there are no solar panels. Where does it get its energy? A small nuclear reactor? Batteries? Super-efficient solar panels that are too small for me to notice? Video inaccuracy?

  3. Lusus Naturae

    I always thought the airbag method was an elegant simple solution for the problem at hand. It certainly wouldn’t work for Curiosity, and I’ll join you in a little anxiety come August, but we’ve got a pretty good track record on Mars (assuming we all use metric!). Safe journey, Curiosity!

  4. Robert

    I hope everyone used the same units this time.

  5. How soon until this video shows up on the UFO nut websites? ‘Cause there were those obvious alien sprites tagging along round about when the upper stage took off.

    //snark

    The landing will indeed be a nail biter. I wonder if any of the orbiters will be able to catch the descent?

  6. Pepijn

    Question: why do the exhaust fumes become clear, a few minutes in, instead of producing thick white smoke? Does it have to do with the lower air pressure? Or is the composition or amount of fuel burned changing?

  7. Terry

    Those are great videos! Thanks for sharing them all in one place.

    One thing I wonder is about all those joints on the gizmos on the Curiosity. Presumably, NASA has used the experience with the other two probes to figure out how to combat the effects of dust on the devices? I’d be interested in learning how they’re doing that. Also, the mobility system – what did they learn from the previous projects about how to build the chassis to keep the thing from hanging up or having other mobility problems?

  8. sarat

    does anyone know where I can track current Curiosity position?

  9. Donnie B.

    Pepijn,

    The smoke is produced by the solid-fuel rocket boosters (SRBs) that burn out and are discarded after the first few minutes. After that, all you can see is the exhaust from the liquid-fueled Atlas. Most liquid fuels produce nearly invisible exhaust plumes, especially in the upper atmosphere (and beyond) where there’s little or no interaction with air molecules.

    The Saturn V was a notable exception — its first stage burned a kerosene fuel that produced a highly incandescent exhaust plume. Its upper stages burned liquid hydrogen so they looked more like the Atlas (after SRB jettison).

    One thing I notice is how very different the current generation of Atlas is from the Mercury Program days. Back then it was a 3-engine booster with some other notable characteristics such as broad fairings and visible turbine exhaust jets. This Atlas seems to be a 2-engine booster with a simple cylindrical shape. I wonder how much else has changed? Is it still a thin-walled balloon as it was in its ICBM incarnation? That was considered an especially touchy machine, easily damaged by a dropped wrench and the like.

  10. Pepijn

    Interesting. Thanks Donnie B.!

  11. Donnie B.

    Patrick,

    All your “curiosity” should be satisfied here:

    http://www.jpl.nasa.gov/news/fact_sheets/mars-science-laboratory.pdf

    To answer your specific question, it has a radioisotope thermal generator, similar to those used on deep-space missions like Voyager. That gives it a steady power source day and night, with no worries about dust accumulation on PV panels. However, there’s a limit to its life span, so the mission probably won’t go 10 or more times its planned length as the previous rovers did.

  12. Bryan D

    It honestly looks way too complicated of a landing, but it’ll certainly be nice if it works out.

  13. Blargh

    That CG video is great – not only does it do a great job of explaining how Curiosity is supposed to land safely on Mars, but it also makes it all look cool. Wait, scratch that: it makes it look awesome. Kudos to its creators!

    @ Patrick:

    Where does it get its energy? A small nuclear reactor?

    Almost: an RTG (radioisotope thermoelectric generator); a generator that produces electricity directly from the heat of radioactive decay.

  14. DanO

    Are they aiming for a July 4th landing date? If so, how much extra money does it cost to make a landing happen on a date coincident with a significant day in history? Wouldn’t it be cheaper to time missions for orbital windows?

  15. Fletcher

    Patrick: The rover is powered by an RTG using Plutonium 238, which we are running out of: http://www.cbsnews.com/8301-205_162-57330362/plutonium-shortage-threatens-future-space-research/

  16. It saddens me that NASA didn’t require the producer of this last video to consult with an acoustical physicist. Tools on Mars wouldn’t sound the same as on Earth. I’m used to the insult of the sound of rockets in space, but I’d really like to hear a simulation of Martian sound propagation.

  17. Donnie B.

    DanO, the landing date is in August, not July.

    I found a Wikipedia article on the Atlas V. It does not use a balloon-type tank, so it’s presumably easier to handle than the old Atlas II and III. The first stage does in fact use a 2-chambered engine rather than the earlier 3-engine configuration.

    However, that engine uses RP1 fuel, the same kerosene-like fuel as the Saturn V. Why its plume is so much less incandescent than the Saturn’s is not explained. I would speculate that (a) its engine may be more efficient, burning the fuel more completely and therefore leaving less unburned carbon in the plume, and (b) we only see the plume at high altitude (after SRB burnout) where there is less oxygen for that unburned carbon to interact with.

  18. rob

    this version of the atlas actually uses a Russian engine, the rd-180. it also burns a kerosene-like fuel so perhaps the lack of smoke is due to the upper atmosphere. and Patrick, it has a small thermoelectric plant powered from the heat of a decaying nuclear source. plutonium I think.

  19. Paul

    Why its plume is so much less incandescent than the Saturn’s is not explained.

    The mixture ratio (mass of oxidizer:mass of fuel) on the RD-180 is 2.72:1. On the F-1, the ratio was 2.27:1. So, the F-1 left more fuel unburnt.

    The RD-180 operates at a higher chamber pressure than the F-1, so the expansion ratio is higher, and the gas at the nozzle exit is cooler, as more of its thermal energy has been converted to kinetic energy.

    Also, the engine is a staged combustion engine, so there isn’t a fuel-rich stream of gas from the gas generator (which in the F-1 was dumped into the nozzle skirt about halfway down; you can see the manifold for it wrapped around the nozzle in pictures of the engine.) In a staged combustion engine (like the SSMEs that were used on the shuttles) all the propellant goes through the main chamber of the engine.

  20. George Martin

    Donnie B. Said: DanO, the landing date is in August, not July.

    The JPL main web page for this mission has a “count down to landing” clock. At 12:35 EST,
    it was 251 days, 5 hours and about 25 minutes to landing.

    George

  21. Chris

    Amazing to see how far we’ve come since the Mars Pathfinder mission. And I don’t just mean the rovers themselves. Also look how much the animations have improved since then.

  22. I love how the lander protection cover + heatshield looks like a classic flying saucer. After so many movies is a sweet revenge when OUR flying saucers invade Mars.

  23. Ben

    The Saturn V is not an exception, it produced no plume either. When Atlas V launches with no SRBs, there is no plume. Only solid fuel produces a smoke trail.

  24. I wonder what that bright blue flare was for on the side of the rocket.

  25. Mike Saunders

    Well, 50% isn’t bad, right?

    Just an update on Phobos-Grunt:
    The ESA has lost contact again with Phobos-Grunt. They will try again on Monday.
    In the mean time, Medvedev, the president of Russia, has said heads will roll over the failure.
    “I am not suggesting that we line people up against the wall like we did when Joseph Vissarionovich was in power,” he added in reference to the firing squads that Stalin used to execute his political foes in 1930s purges.

    “Nevertheless, we have to punish them seriously.”

  26. Russ Taylor

    The half-life of Pu-238 is 88 years so after the planned 2-year mission the output of the RTG will still be 98% of it’s initial value. It does not seem that electrical power should be a limiting factor in extending the life of the rover.

  27. TSC

    I have to say, these little cameras attached to rockets are *exactly* the right way to make launches more interesting for the media and general public. They put you right there. It’s exciting in a way that watching a rocket disappear into the void just… isn’t.

  28. @#19 Rob and #20 Paul: One thing I think is fascinating about the RD-180 powering the Atlas is that it’s derived from the RD-170/171, which was developed for the Zenit rocket, used in various configurations to boost the Energia (also used in an analogous role to the SRBs in the US Shuttle program, boosting the Energia-Buran launch stack).
    There’s more history behind it, too, but in a nutshell, you have a very effective engine design that was originally intended to one-up the US and to launch Soviet military systems like the Polyus, which was intended to neutralize the strategic advantage of the US SDI.
    And now it’s powering NASA (as well as US military) launches!

    @26 Mike Saunders: I do hope that’s a joke.

  29. Sam H

    @25 Noel: took the words right out of my mouth. I remember them referencing pyros at that point in the video; would that blue light resembling a flare be related to those systems??

  30. Paul

    Joseph G.: it’s interesting to compare the RD-180 with Space X’s Merlin engine. The latter has lower chamber pressure, lower thrust, and lower specific impulse. And yet, it’s very cheap, and enables Space X to price their launchers below anyone else (even the Chinese).

    The contrast between performance optimization and cost optimization has sparked a running debate in the aerospace industry since the 1960s, when the late Arthur Schnitt started asking the right questions. Some of his reports are available online:

    http://www.dunnspace.com/home.html

  31. Paul

    The half-life of Pu-238 is 88 years so after the planned 2-year mission the output of the RTG will still be 98% of it’s initial value.

    I think the output of the RTGs declines a bit faster than that, due to radiation damage to the semiconductors that convert heat to electricity.

  32. ND

    Is it me or does that rocket accelerate rather fast? I guess I’m used to seeing the heavier shuttle carrying humans cargo.

  33. Kurt Erlenbach

    The plutonium used to power spacecraft like these makes launches a bit more interesting. I live near KSC, and I biked out to the visitor center yesterday to watch the launch. The county has a “plutonium disaster plan” in case things go badly at the time of launch, which, needless to say, has not been needed. Cassini was the first spacecraft to use plutonium, and this place was crawling with protesters in the 90s when it launched. None in sight yesterday.
    http://www.floridatoday.com/article/20111127/NEWS02/311280002/Plutonium-disaster-plan-back-shelf?odyssey=mod|newswell|text|Home|p

  34. #34 Kurt:
    “Cassini was the first spacecraft to use plutonium”.
    Really??? Ever heard of Voyager???

  35. ND @33 — Yes, it certainly went upstairs in a hurry, even compared to a shuttle. Thirty years ago, when I watched the first STS launch, I was startled by how quickly it cleared its own length, compared to a Saturn V.

    Wow, that landing process is something. Sure hope it works. (I guess the descent rocket-crane stage simply crashes; wonder how far away from the rover it’ll be. Maybe they can roll over and take a look.)

  36. Blargh

    “Cassini was the first spacecraft to use plutonium”.
    Really??? Ever heard of Voyager???

    Heck, Pu-238 RTGs were already in use in the Apollo program

  37. Donnie B.

    Ben,

    Quite right about the S-I stage not leaving a smoke trail. However, I was referring to its incandescent exhaust plume or “flame tail”, which it certainly did exhibit. The Atlas in this video shows a “clear plume” and that’s the distinction I was curious about.

    Thanks to Paul for his explanation, which supports my speculations.

    As to the F1 engine, it was certainly the “dirtiest” liquid fueled rocket motor I’m aware of. The turbine exhaust was so nasty there was a region extending at least a meter below the nozzle where the plume was completely shrouded and “dark”. For years, when watching the launch videos, I thought this dark-plume region was a physical nozzle extension. It was something of a revelation when I learned the real explanation — an opaque cooling layer that hides the real exhaust.

  38. ND

    The payload fairing jettison is neat. Around 3:40m mark. It’ passes awfully close to the rocket as it fall off.

  39. Torbjorn Larsson, OM

    #31:

    As I remember it SpaceX will attempt to up the engine efficiency by staged combustion (reuse the turbine propellant) to adapt to the reusable landing gears that will lower launcher efficiency.

    Added development and engine cost, but lowered launcher cycle cost.

    #32:

    “I think the output of the RTGs declines a bit faster than that, due to radiation damage to the semiconductors that convert heat to electricity.”

    I just had to estimate the Voyager’s RTG lifetime from the latest curves during a discussion of how far they will go. Those RTGs last ~ 60 years until mere watts remains. (Then it comes down to their 5 V (presumably) electronics.)

    Now the new MMRTG were developed since the old high quality thermoelectric elements weren’t available, I believe. I dunno how the new elements stack up.

    Voyager has an added element of higher cosmic radiation levels, which we know hurts semiconductor materials. While Curiosity has added Mars’ surface natural radioactivity minerals, which I presume is negligible.

    Also, Curiosity will need more than “mere watts”, if it wants to walk the walk instead of just talk the talk. (O.o)

    #34:

    RTGs were used on Apollo missions for site experiments, and on Viking 1&2 , Pioneer 10&11, Voyager 1&2 (and probably more, taking from memory) and countless military crafts.

    It is routinely used post Mars orbit AFAIU.

  40. vince charles

    # 24. Ben Said:

    “The Saturn V is not an exception, it produced no plume either. When Atlas V launches with no SRBs, there is no plume. Only solid fuel produces a smoke trail.”

    No, Paul (#20) had it. Early kerosene rockets were fairly “dirty,” and left much partially-burnt fuel in the exhaust. Carbon-carbon bonds emit in the visible-light range, and thus give yellow-orange plumes. You can see this in most kerosene heaters. Cleaner flames, such as high-purity natural gas and methanol, cannot have much carbon-carbon bonds, and give dim, bluish flames. In the middle are clean-burning hydrocarbons, such as high-purity propane or efficient kerosene, as the RD-180 is.

    What solid-fuel motors leave is a combination of high-carbon molecules, particles of fuel that are large enough to still be burning even down the exhaust trail, and droplets of aluminum. The aluminum may still be hot enough to glow, adding more light. Even the (relatively) cool aluminum adds opacity, and a “thick” trail.

  41. vince charles

    # 25. Noel Said:

    “I wonder what that bright blue flare was for on the side of the rocket.”

    Hydrogen vent. The boiled-off hydrogen gas is piped off, otherwise the fuel tank would burst. Here’s the terrestrial equivalent:

    http://en.wikipedia.org/wiki/Gas_flare

  42. vince charles

    40. Torbjorn Larsson, OM Said:

    “As I remember it SpaceX will attempt to up the engine efficiency by staged combustion (reuse the turbine propellant) to adapt to the reusable landing gears that will lower launcher efficiency. Added development and engine cost, but lowered launcher cycle cost.”

    Meh, it depends on the details of the implementation. Higher-efficiency engines may or may not pay back their development and manufacturing costs with operational savings. The SSME didn’t, but its Soviet response seems like it did (at least, if it had kept flying).
    .

    “Now the new MMRTG were developed since the old high quality thermoelectric elements weren’t available, I believe. I dunno how the new elements stack up.”

    Dunno, but it seems to me the new RTG design is mostly just better “customer service” on the part of the engineers. The thermocouples use some odd materials, but nothing truly exotic.
    .

    “Voyager has an added element of higher cosmic radiation levels, which we know hurts semiconductor materials. While Curiosity has added Mars’ surface natural radioactivity minerals, which I presume is negligible.”

    Mars radiotopes are negligible compared to its shielding effect- when you’re on a body, space radiation is by definition coming at you from half as many directions. And this is ignoring an atmosphere, which even on Mars is still not something to ignore. Mars is also deeper inside the Sun’s sphere of influence, which contributes electrons and protons but decreases cosmic rays. The electrons and protons, being “softer,” are then decreased significantly by Mars.
    .

    “RTGs were used on Apollo missions for site experiments, and on Viking 1&2 , Pioneer 10&11, Voyager 1&2 (and probably more, taking from memory) and countless military crafts.”

    Soviet military craft, sure. But both US and Russian organizations soon found they were more trouble than they were worth, particularly as solar arrays and batteries kept getting better and better.
    .

    “It is routinely used post Mars orbit AFAIU.”

    Less and less. NEAR pushed that boundary, and Rosetta is smashing it.

  43. Grand Lunar

    Weren’t you at home then with sinus trouble, Phil?
    If so, how could you miss it? Could you use NASA’s TV website to catch the launch?

    Anyway, nice video, especially to see what I missed (had to leave for work just after the first MECO of the Centaur).

    I still wish we could get views of these types of rocket launches similar to what we lately had with the shuttle (i.e, multiple external views from the rocket itself during ascent).
    But I suppose that’s too costly, and you have a problem with receiving quality footage.

  44. vince charles

    44. Grand Lunar:

    We’re getting views of these types of rocket launches- the Shuttle just buys and installs more cameras, on more vehicle locations, from the same vendors. Other than quantities, the ground and onboard cams are pretty much the same for both vehicle types.

  45. Seems like an awful lot of things have to go right in that landing. Hope they do.

  46. @31 Paul: Joseph G.: it’s interesting to compare the RD-180 with Space X’s Merlin engine. The latter has lower chamber pressure, lower thrust, and lower specific impulse. And yet, it’s very cheap, and enables Space X to price their launchers below anyone else (even the Chinese).
    The contrast between performance optimization and cost optimization has sparked a running debate in the aerospace industry since the 1960s, when the late Arthur Schnitt started asking the right questions. Some of his reports are available online: [snipped]

    That’s an interesting site! I’ve only read a couple of those essays, but the one on the SSTO really made me rethink what I thought I knew about launch economics (admittedly very, very little) :)
    I thought this bit was interesting:

    As far back as 1959, while employed by Space Technology Laboratories (split in 1961 to form The Aerospace Corporation and the TRW Systems Group) I was astonished to discover that ballistic missiles, space launch vehicles and payloads (satellites) have been and are being incorrectly designed to airplane design criteria that calls for the minimization of weight and maximization of performance. The criteria is ingrained in all aeronautical engineers, and its use results in minimizing the cost of most winged aircraft. At that time, I introduced a more appropriate criteria for the design of space systems that I called design for minimum cost, or, minimum cost design (MCD). I crudely showed that the application of the new criteria has the potential for appreciably reducing the costs of space operations.

    That makes a lot of sense – if you’re designing an airliner, for instance, fuel is going to be one of your primary costs (if not THE primary cost) in the long term, so fuel efficiency is a key design parameter. It’s understandable to invest in expensive, light composite construction and high-tech, high-efficiency engines.
    On the other hand, when designing a rocket, only a relatively tiny percentage of launch costs are related to fuels, particularly if it’s not a reusable vehicle, so ISP isn’t necessarily your best measure of efficiency in terms of dollars per kilo.
    That probably explains why the Shuttle used liquid hydrogen – it gives you (pretty much) the highest specific impulse you can get out of chemical engines. Your fuel systems have to be more expensive, and you need a huge fuel tank, but as the Shuttle was originally intended to be a “spaceliner” that would make lots and lots of flights, it made sense to try and minimize fuel weight and consumption.
    Amirite? :)

  47. @43 vince charles: Meh, it depends on the details of the implementation. Higher-efficiency engines may or may not pay back their development and manufacturing costs with operational savings. The SSME didn’t, but its Soviet response seems like it did (at least, if it had kept flying).
    Then at the other end of the scale, you have the OTRAG approach (those who are interested should Google it – I’m trying to give the moderator a break from links ;) ). Based on what little I’ve read about it, it looks like the whole program was trashed, so unfortunately, it looks like we’ll never really know how well it would have actually worked. Who knows, though, maybe the new Libyan government will dig up some old stuff on it.

  48. Paul

    The radiation damage in RTGs comes mostly from radiation from the RTG itself, I believe. 238Pu emits 2600 neutrons per second per gram, since it occasionally decays by spontaneous fission (and that will also cause gamma emission). Neutrons from (alpha,n) reactions are minimized by making the oxide using isotopically pure 16O and by avoiding low atomic number contaminants.

  49. Messier Tidy Upper

    I love that we can get video like this now!

    Me too – and I love seeing it live on a computer screen that doubles as a TV even more. ;-)

    Thankyou NASA-TV. :-)

    Congratulations again to all the folks who designed, constructed, are now flying and will – all going to plan – soon be driving this new awesome, best-yet of Mars Excursion Rovers. Bon Voyage Curiosity, here’s hoping you have a safe, smooth and successful flight and landing. Can’t wait till August 2012 to see what you find! 8)

  50. Kevin

    #42
    I appreciate your answer, but the fountain sparkler is still bugging me. I can understand the process of vent hydrogen on the ground, but while in powered flight I thought hydrogen was vented via the engines.

    Also, why would one want burning hydrogen shooting out of the side of a rocket and all the uncontrolled lateral forces that presents?

    I’m not a rocket scientist so you can say “it’s just how it works” and I’ll be placated.

  51. zeke

    @52 Kevin,

    Its a LH2 vent fin — a small pipe. The RL-10 engine, which powers the second stage of the rocket and is enclosed inside the fairing, uses liquid hydrogen as fuel. The LH2 is constantly boiling off producing gas, some of it is used to keep the tank pressurized, the rest must be vented overboard as a gas (it is not ignited) to avoid an explosive situation in the enclosed and confined interstage area while the RL-10 engine is inactive.

    After the fairing is jettisoned, the H2 gas is simply vented directly to space causing the flare/glow that you see.

    As far as any thrust is concerned resulting from the venting, it is trivial compared to the muscle of the RD-180 engine which powers the first stage — there is a lot of control authority from it.

  52. Kevin

    @53

    Makes sense. Thanks!

  53. artbot

    I’ve watched that landing animation at least 15 times over the last few months and I still can’t figure out the reason behind lowering the lander on cables at the end. From the way the engine unit flies off, I’m guessing that it’s either to avoid the rockets kicking up dust into the lander (were it to stay attached), or to avoid contaminating the landing site with rocket fuel/exhaust. Anyone know ?

  54. @55 artbot: Well, I don’t think local exhaust contamination is a concern – the engines are already pretty darn low, and this rover has legs (figuratively speaking) and is probably going to roll quite a ways before taking any soil samples anyway.
    Now, this is just a guess, but my bet is that it’s because most liquid rocket engines don’t have an “idle” – that is, even though they can almost all be throttled, their minimum thrust setting might be something like 50 percent. It’s apparently difficult to design pumps and engines so that lower flows of fuel/oxidizer don’t cause combustion instabilities. Anyway, these rockets are designed to slow this heavy rover down from something like 1000 kph, so I’m betting that they start off at full power, then throttle down when it’s time to drop off the rover. Without the weight of the rover, the engines probably can’t be throttled down enough to land, period. They’re already at the low end of their thrust range, so when the lander disconnects, the engine platform HAS to fly away. It doesn’t have any choice :)

  55. Donnie B.

    The alternative would be to have the rockets carry the rover all the way to the ground, as with the Surveyors. But that leaves you with the problem of how to get the rover off the lander. I can think of several methods (ramps, motorized “garage doors” and the like) but they all seem like they would add weight, bulk, and/or complexity.

    Imagine how you’d feel if you got the lander safely on the ground, but then your garage door jammed!

  56. Hevach

    Looking at the engine platform, I can imagine a lot of things they could do with that system besides dropping a single rover.

    Imagine instead of hovering, it had some means of horizontal thrust. It could skim over rough terrain where a rover couldn’t drive and a lander couldn’t see anything, collecting data from the air and releasing a number of impact probes like the ones the failed polar lander had.

    I’m a big fan of rovers, they’re cool for all kinds of reasons, but there’s places they can’t go. I can see this system being adapted to get the kind of area coverage you get with a rover in those places.

  57. Ben G

    Ok, this is a nit, but a big one of mine… NASA did not “launch” Curiosity, United Launch Alliance, launched Curiosity, which NASA built.

  58. @58 Hevach: I like the way you think :D Still, a rocket-lifted probe is going to have a flight time measured in minutes. I’d love to see a balloon of some sort, that could drift and gather data over a huge range. More ambitiously, I’d love to see one of those fabled nuclear isomer/stimulated gamma emission powered aircraft engines, powering a UAV!
    The flight sim/aircraft designer X-Plane has, for some time, simulated Martian flight as well as flight in the Earth’s atmosphere (it even comes with a fictional “jet sailplane” aircraft capable of flight on Mars). It’s tricky to design an airframe that works (your lowest possible stall speed winds up being something like 600 miles per hour!), and your aircraft ends up handling like a truck on ice, but it is possible.

  59. Cairnos

    @57 – It would be as frustrating as getting your vehicle into orbit and then having it shut down and just sit there

  60. I’m OK with the foley effects for the rocket and such. I like to think of it like this, the mic is attached TO the spacecraft itself and not floating in space beside it. Then you’d at least get something sort of like this. So long as you have a medium and a mic, you’ll hear something!

    This is a good example: http://youtu.be/LhnU3KB_fi0

    The air is pretty thin at 40 miles but we still hear the bolts fire. And even then, the SRBs are still traveling upwards but we continue to hear SRB fuel bits (I’m assuming) roll around inside the metal body. The sound isn’t traveling by way of air but by vibrating the actual SRB itself. The mic pics that up.

    It’s like tapping on a hard surface, we can hear it a bit but if we rest our ear on that same surface, it’s much louder. So even in deep space, as long as your ear was on the object, you’d hear it if you were banging it with a hammer. Sure, there’s that whole suffocating/decompression issue but dangit you’d hear it before you bought it!

    I’ll end by saying that to garner interest in these things, people need familiarity. You can better understand how sound travels, or doesn’t travel, in space after your interest is gained. Seeing a soundless video doesn’t make sense to us land dwellers where sound via air is plentiful. Finally, as a creative type myself, I’d feel so very weird putting a video together with no foley. It’s just plain fun. :)

  61. artbot

    @57. Donnie B. – Yeah, I wondered why they couldn’t just make a rocket powered platform that the rover would sit atop, then simply drive off. Then it occurred to me that perhaps the rover on cables acts like a pendulum stabilizer for the rockets. If the rover were atop a platform, it would require much more nuanced engine control to keep it stable, whereas with the “rocket crane” the load of the rover keeps the center of gravity low and more stable. Just another guess :-)

  62. John Kingery

    HI. Was wondering about the camera perspective above, looking at the lander from below.(behind?) What is the flattish corrugated surface we’re looking over? Where would this camera be on the rocket?
    Really enjoyed watching the launch, especially the reactions of the JPL crowd when separation occurred and Curiosity was safely on its way.

  63. Jim Baerg

    For more on the power source see:
    http://atomicinsights.com/2011/11/building-curiositys-power-source-at-idaho-national-laboratory.html

    Also for information on RTGs up to the mid 1990s see
    http://atomicinsights.com/article-file
    & scroll down to September 1996 for a few articles.

    Solar is best for many space applications, but on a planetary surface where you have to deal with night or if you’re a long way from the sun something nuclear is the way to go.

  64. Ben

    RTGs were also used on [US missions such as] Galileo, Ulysses, New Horizons, Cassini, the Apollo missions, Voyager 1 & 2, Pioneer 10 & 11, Viking 1 & 2 on Mars, and several other civilian and military missions and experiments such as Transit and Nimbus satellites. One mission in the 1960s was lost in a launch explosion; the reactor was recovered intact from the Pacific and flown again on another mission.

  65. Paul

    It’s apparently difficult to design pumps and engines so that lower flows of fuel/oxidizer don’t cause combustion instabilities.

    The bigger problem is with the injector. Conventional injectors don’t work well at low flow rates. However, it’s possible to design injectors that do work well; the pintle injector in the Lunar Module Descent Engine (LMDE) worked over a wide range of flow rates, enabling that engine to be throttled to 10% of max thrust.

    Space X’s Merlin uses a pintle injector, btw.

    Engines operated in the atmosphere also suffer from flow separation if the nozzle exit plane pressure is too low. This means that if they are highly throttled they either need variable geometry nozzles (plug nozzle, for example), or they need to be very underexpanded at high thrust. Engines operated in vacuum do not have this problem.

  66. Blargh

    @67 Ben

    One mission in the 1960s was lost in a launch explosion; the reactor was recovered intact from the Pacific and flown again on another mission.

    As a rad guy, I have to point out that an RTG is not a reactor – RTGs run on plain old radioactive decay. A nuclear reactor is one that contains a nuclear chain reaction: the only fission that occurs here is spontaneous (roughly twice per billion radioactive decays, a Pu-238 atom will spontaneously fission – split – instead of emitting an alpha particle) and unwanted, as Paul pointed out in comment #49.
    Although to add to/correct his post, Pu-238 does emit some gamma radiation through its “normal” decay as well. But it’s not a lot, and it’s low-energy, which makes it easy to shield against (which is why this particular isotope is used). It gets worse over time (timescale of years) as other radioactive decay products build up, though.

  67. kansel

    Surely I’m not the first to note that Curiosity launched on Caturday?

  68. @68 Paul: Interesting. I was wondering about that lunar descent engine!
    Here’s a blog post on pintle injector rocket engines that I found while Googling the term, if anyone else is interested.

    @69 Blargh: Am I correct to assume that an actual reactor would be able to get a heck of a lot more power out of that amount of plutonium? 125 watts doesn’t sound like a whole lot, for 2000 watts of waste heat. I assume that RTGs are used because no supervision (or moving parts) are needed?

    @70 kansel: Heh, here’s what I got when I did a search for “curiosity” on Cheezburger.

  69. Mathias R.

    @70.kansel: So, curiosity killed the cat?

  70. @71 Artbot: I did some image searches for diagrams on Google. It took awhile, but I found it – that’s the liquid oxygen feed line. Presumably it’s heavily insulated, which is probably why it’s so big. Kinda makes sense to put the camera there, as it’s slightly further out from the body of the rocket, giving a slightly better view.

  71. Blargh

    @ Joseph G:

    Am I correct to assume that an actual reactor would be able to get a heck of a lot more power out of that amount of plutonium?

    Wrong isotope of plutonium, I’m afraid. :)
    While you can technically burn Pu-238 in a reactor – it’s fissionable (capable of undergoing fission), and, more importantly, fertile (capable of capturing a neutron and turning fissile (with an extra neutron it turns into Pu-239, which is the isotope that’s used in bombs and mixed-oxide reactor fuel)) – it won’t make a reactor fuel on its own.
    Furthermore, even if the “right” isotope was used, I don’t think (this is a bit outside my particular field :)) the amount used in the MMRTG – 4.8 kg – is enough to sustain a chain reaction.

    125 watts doesn’t sound like a whole lot, for 2000 watts of waste heat. I assume that RTGs are used because no supervision (or moving parts) are needed?

    Yep. Without moving parts, and relying on relatively simple principles, RTGs are extremely reliable. They’re also much smaller and lighter (an order of magnitude or so) than the smallest reactors ever built.
    I know research has been carried out with Stirling engine-based RTGs, which would trade complexity for a much higher efficiency, but I don’t know what the current situation is with those.

  72. @75 Blargh: Thanks for the info! I had no idea Pu-238 wasn’t used in actual reactors.
    Still, I find nuclear tech fascinating (probably to an unhealthy degree). I’m the kind of nutball that in an earlier age thought that the Ford Nucleon was a wonderful idea :D

    I know research has been carried out with Stirling engine-based RTGs, which would trade complexity for a much higher efficiency, but I don’t know what the current situation is with those.
    That does make a lot of sense, especially for applications like a Titan probe where there’s no shortage of working fluid and plenty of cooling through conduction. Still, the image of a space probe with a big steam-age-looking piston moving back and forth somehow tickles my funny bone :)

  73. jt_flyer

    This is NASA’s most exciting mission in years… especially the landing sequence. Thankfully the military space truck has been retired we and can get back to real space exploration.

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