More on Orion to NEOs

Boris_Badenov · Feb 8, 2007

WOW, Apophis has a great close pass between Sep. 2020 & Feb 2021. On the orbital simulation it is within .3 AU the whole time. <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

j05h · Feb 8, 2007

> WOW, Apophis has a great close pass between Sep. 2020 & Feb 2021. On the orbital simulation it is within .3 AU the whole time. Yeah, and has a non-zero collision risk in 2036. It passes really close to Earth often, it is the best candidate IMHO for a first asteroid to move, but that is beyond the first Orion. Not sure what the delta-V is to meet up with it, but shouldn't be to aggresive. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

spacester · Feb 9, 2007

I'm pretty sure that Apophis is a perfect illustration of the trade-off between dV and launch windows I mentioned. With the orbital periods being so close, if the timing is off for your Hohmann transfer, you're going to be waiting multiple orbital periods, i.e. years, for them to line up. All other current-technology-dV-trajectories are just variations on the Hohmann transfer, at least when it comes to Earth/Mars and Earth/Venus, so the waiting time is essentially the same. I know this from the simulations I've run. But I've never run many simulations on NEOs, mostly because when the orbits get more than a bit eccentric, my timing algorithm breaks down. (The software is in mothballs.) I know the dV penalty of the more direct (shorter trip time) trajectories will be a lot less due to the small difference in periods (i.e. semi-major axis), but how much less I can only guess. It is going to be very interesting and not simple. There are ways to work around the timing so that you can launch more or less when you want to, but they all take more dV and it's a question of how much. In some cases certain launch periods will be just ridiculous in terms of high dV AND a long trip time. IOW theoretical solutions will exist with very high dV requirements but if you launch later you spend less dV and get there about the same time. There are lots of tricks: Lambert's solution; something called a "biconic" approach (having nothing to do with re-entry vehicles); multiple patched conic transfers (several engine burns on the way, a staging orbit approach); combined constant thrust (ion engines) and periodic high thrust (storable propellants, solids even?) come to mind. I am *really* looking forward to seeing what Mr. Griffin's folks come up with on this subject. BTW, did I mention I'm a Solar System? <img src="/images/icons/laugh.gif" /> <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

spacester · Feb 9, 2007

Thanks. Hmm. . . I appear to be a red giant, not an Orange star. But of course I disagree about the moot point thing. It is clear that your idea of moot and mine are worlds apart. I strongly disagree on several levels actually, in fact that statement kinda strikes a nerve. And I respectfully observe that you are dead wrong about any comet being within the dV of an Orion. Not even close, by my reckoning. Remember, we're talking NEOs here, not main belt, let alone things falling into the gravity well from the top. It's a matter of orbital energies. When a comet is in the inner solar system the angle between its flight path and *anything* from cislunar space will be a HUGE angle and vector arithmetic will show HUGE dV requirements for rendezvous. I'll guess 15 - 20 km/s !! The dV capability of the Orion is known, as least from inference, is it not? That is the only parameter needed to start talking about the possibilities for that capability. I find your statement rather bizarre, actually, I must be reading more into it than intended? I'm not here to argue, just accurately explore the title topic . . . . <div class="Discussion_UserSignature"> </div>

darkenfast · Feb 10, 2007

My previous ideas involving missions to LEO's involved the Ares V and a mod LSAM: the descent stage was stripped of landing gear, the ascent stage was just the cabin (no engine), functioning as a hab/airlock/storage module, with other consumables outside. Landings would be accomplished with MMU's. If a mission is desired sooner than Ares V is available, I was wondering what sort of hardware could be used to expand the volume of the CEV at a low cost? How about the airlock module from the ISS? It contains two rooms: the airlock itself, and the compartment where the suits are stored and EVA preps are done. If the airlock is packed with food and other supplies, I think we have enough volume for a 2-3 man crew to function, and at a fairly low cost (especially if a back-up unit from the ISS program is available to be modified). The next problem is: how to get it to the asteroid? I don't think it's worth spending the money to upgrade the Delta IV further (as suggested in one of the references). Perhaps this is another reason to get the Ares V built. This would allow much more flexibilty in mission planning and we do need the heavy lift capability anyway. Summing up, I think I still like my Ares V/mod-LSAM best. The EDS performs the burn that sends the craft to the LEO. The LSAM descent stage puts the craft into orbit near the LEO and performs at least part of the TEI burn, with the CEV engine available if neccessary (CEV/mod-Ascent stage, minus Descent stage at that point). I'm not sure of the Dv requirements, perhaps someone can make a better guess. Boil-off of the LSAM's hydrogen might be a problem. And, of course increased shielding is another issue. However, it might allow a four-man crew, perhaps two regular astronauts and two scientist-astronauts. I'd go! Comments?

Boris_Badenov · Feb 10, 2007

This sounds like a pretty good plan, but. How about the airlock module from the ISS? The Shuttle is the only lift vehicle capable of putting this into orbit. Boil-off of the LSAM's hydrogen might be a problem IIRC the LSAM will use hypergolics. <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

gunsandrockets · Feb 10, 2007

"...the LSAM will use hypergolics." The baseline LSAM uses hypergolics in the ascent stage and LOX/LH2 in the descent stage. It's the big load of high ISP propellant in the LSAM descent stage which provides a lot of the improved mass delivery of the project Constellation lunar architecture compard to Saturn V/Apollo. In fact I'm waiting to see just how the contractors and NASA go about solving the design problem of huge liquid hydrogen tanks on the descent stage. The size of the tanks makes the baseline LSAM (which uses the old LM configuration) into a towering lander. Previous NASA studies for landers which used liquid hydrogen settled on a lunar-crasher stage configuration to solve the problem. I still think that's the best way to go short of the sophisticated Lockheed solution of a 'dual-axis thrust lander'.

gunsandrockets · Feb 10, 2007

"I don't think it's worth spending the money to upgrade the Delta IV further (as suggested in one of the references). " The improved launch capability mentioned isn't some new design, it's existing capability by strapping on a few small solid rockets onto the 3-core heavy lift configuration. Any real new capability would involve larger and more efficient versions of the Centaur upper stage, and that capability might be developed for purely business reasons regardless of what NASA does with the Orion. But the final and most important factor is -- until we know exactly what the target mission is and therefore what kind of delta V is required it's impossible to know the best booster choice. It could be that any likely candidate for a NEO mission would require the much higher capability of an Ares IV or Ares V launch.

gunsandrockets · Feb 14, 2007

"Its working fine for me. " Still not working for me.

gunsandrockets · Feb 14, 2007

"Perhaps any of these 433 Eros, 1036 Ganymed, 1620 Geographos, 3908 Nyx, 4179 Toutatis, 4183 Cuno, 25143 Itokawa, 99942 Apophis, etc." Using orbital period as a shorthand for the delta V needed to reach the object, only 99942 Apophis with an orbital period of 323 days looks promising of those objects you listed. The next closest had a period of 507 days. But I have some more candidate NEA's! 2002 AA29 60 m object made close approach in 2003 http://en.wikipedia.org/wiki/2002_AA29 3753 Cruithne 5 km object http://en.wikipedia.org/wiki/3753_Cruithne 2000 PH5 1998 UP1 What's interesting about these objects is they are essentially in the same orbit around the sun as the Earth, but in what's sometimes called a 'horseshoe orbit'. http://en.wikipedia.org/wiki/Horseshoe_orbit Since these objects are essentially in the same orbit as Earth, delta V should be minimal. The only complication might be travel time. I'm guessing Cruithne is about 1/4 orbit behind the Earth right now. UPDATE Apparently there is a term for these objects which closely mimic the path of the Earth, 'co-orbital objects'. It's the co-orbital NEA which should be the easiest targets for Orion to reach.

spacester · Feb 14, 2007

G&R, you got me to poking around my archives. (I have got to find the time to bring some of my files to the light of day. Somewhere I have a list of candidate NEOs circa 2002.) Ever hear of the Earth Grazing Opportunity Mission to Analyze Newly Identified Asteroids and Comets probe? <img src="/images/icons/smile.gif" /> <img src="/images/icons/laugh.gif" /> Now that's MY kind of spacecraft design! <div class="Discussion_UserSignature"> </div>

gunsandrockets · Feb 14, 2007

Here is an interesting link... http://en.wikipedia.org/wiki/List_of_NEAs_by_distance_from_Sun ...making it easy to find more potential NEA candidates.

3488 · Feb 14, 2007

Thanks gunsandrockets. Interesting link. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

j05h · Feb 14, 2007

Of all the objects you listed, Apophis is the one NEO that should command our interest. It would be beneficial to understand as much about it (human mission) as soon as possible, so that we are ready to act if it becomes a collision problem. Basically, if it doesn't hit in 2036, it will hit sometime geologically-soon. Apophis might have significant industrial potential. Instead of "nuking" it, we can build space infrastructure out of it, consuming the asteroid before it can damage the Earth. Interesting news that there are more "horseshoe" objects. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

mithridates · Feb 14, 2007

Which one is that, not 2002 AA29 is it? <div class="Discussion_UserSignature"> ----- http://mithridates.blogspot.com </div>

mrmorris · Feb 14, 2007

"Basically, if it doesn't hit in 2036, it will hit sometime geologically-soon." That's an unfounded statement. The fact that currently its path generates a 'near-miss' with earth around 2036 doesn't guarantee that it will collide at some point in the future. Close encounters with Earth will cause the trajectory of the asteroid to change -- but that change is not necessarily *closer* to Earth. I recall reading an article a few months back -- I *believe* it was about KBOs, that was talking about how near-misses with Jupiter during the formation of the solar system could have flung objects to the edge of the solar system. Likewise a near-miss involving Earth and Apophis at some point in the future could change its path in such a fashion that it no longer even crosses Eath's orbit. Mind you -- stating *that* will be the case would be unfounded as well. The best that can be said at the moment is that the scientific community is confident that it poses no immediate danger.

j05h · Feb 14, 2007

> That's an unfounded statement. No, if the 2029 "keyhole" isn't reached, it will likely encounter the same issue in 2036, becoming a collision hazard later in the century. There are many possible dates, depending on orbital conditions. This has been in the news in the past, but I don't have time to look it up. I understand your logic (it is correct, per se) but the hazard from Apophis is none-zero and potentially growing after 2029. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

subzero788 · Feb 14, 2007

"I understand your logic (it is correct, per se) but the hazard from Apophis is none-zero and potentially growing after 2029." The chance of an impact in 2036 is currently estimated at about 1 in 45,000 and classified Level 0 on the Torino Scale, which means "The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage." Apophis poses no more threat than any other known NEO and shouldn't be considered a higher priority target for a human mission than any other NEO.

solarspot · Feb 14, 2007

If you're looking for NEA names... look up this bunch... all relatively easy to get to from Earth: 1991 VG (between 5-15m diamater) 1998 KY26 (20-50m) 2002 NV16 (90-230m) 2002 AW (200-450m) 1991 JW (350-800m) 2004 MN4 (350-800m) And Finally 2006 GB Shouldn't be too hard for everyone to find info on those 7 based on the names... right?

mrmorris · Feb 15, 2007

"I do not think you can say his statement was unfounded..." His statement that I quoted specifically states "it will hit sometime geologically-soon". That statement is unfounded, period. You cannot state with certainty that this will be the case because it is not certain that Apophis will *ever* hit Earth, much less in any given timeframe.

mrmorris · Feb 15, 2007

"I understand your logic (it is correct, per se) but the hazard from Apophis is none-zero and potentially growing after 2029." This is a perfectly valid statement. Mind you, it's also possible to state: "The hazard from Apophis is non-zero but potentially shrinking after 2029." <img src="/images/icons/smile.gif" />

silylene old · Feb 15, 2007

Asteroid 1950DA is the most dangerous NEO, and is due to make a very close pass in seven centuries from now in 2880 (currently has a 1 in 300 chance of collision). This object is large and fast, and would be a continental level killer if it collides. We have 57 years worth of orbital information on this object currently, and so we know its future orbit, considering that which we understand quite well, and based upon the factors which we understand well, the chance of collision is uncomfortably high. What we don't understand very well for future trajectory predictions are several very small but important effects, such as the impact of solar radiation, solar wind, thermal re-radiation (Yarkovsky effect), mass distribution of the object, rate of rotation and how this impacts thermal re-radiation, etc. These very minor effects can cause significant orbital pertubations, especially 7 centuries into the future. So the chance of collision in the future is probably less than 1 in 300, but it could be more. If there is any asteroid which will require a future visit and mission, this is it. On the upside, we have 769 years to plan for this, if needed. But if a diversion of the object were necessary, it would be much , much easier to do sooner than later in terms of energy required. If we did send a mission to an LEO, I prpose we land a radar beacon, laser reflectors and instruments to monitor solar wind, radiation, temperature on the surface of 1950DA. Such instruments and beacons would allow us to track its orbit far more precisely. And even more important, by tracking its actual orbit versus its projected orbit, and with strong knowledge of irradiation and solar wind effects, we can then understand and model these minor trajectory perturbations and their impact on the object's future motion. This will allow a much better calculation into the future of 1950DA and a much better assessment of whether there actually is a risk. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

MeteorWayne · Feb 15, 2007

"If we did send a mission to an LEO, I prpose we land a radar beacon, laser reflectors and instruments to monitor solar wind, radiation, temperature on the surface of 1950DA. Such instruments and beacons would allow us to track its orbit far more precisely. And even more important, by tracking its actual orbit versus its projected orbit, and with strong knowledge of irradiation and solar wind effects, we can then understand and model these minor trajectory perturbations and their impact on the object's future motion. This will allow a much better calculation into the future of 1950DA and a much better assessment of whether there actually is a risk. " You hit the nail right on the head here. For something (which may be the most dangerous) to be 7 centuries in the future is a great opportunity to measure and test models. That is the best way for us to refine said models to be able to more accurately predict the motion of NEO's in the future. Besides, with 25 years to plan there should be a superb "most bang for the buck" mission possible. MW <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

gunsandrockets · Feb 15, 2007

"...he next near pass of 1950DA is in 2032. This would be an excellent time target for my proposed mission." For the reasons you cited 1950 DA is an excellent target for a science mission. But for some of the reasons you cited it also is a bad choice for a pre-2020 Orion manned mission. 1950 DA requires a fair amount of delta V to reach. The orbital period of 1950 DA is 809 days. Even so 1950 DA sounds like an excellent target for a near term unmanned mission.

Boris_Badenov · Apr 3, 2007

Here is a new article from The Space Review on possible NEO missions. Asteroid missions: be patient, or bring lotsa gas by Tom Hill Monday, March 26, 2007 There’s been an upsurge in interest in crewed missions to visit a near Earth asteroid. The prospects of new spacecraft, along with the more distant, yet still possible, larger rockets to push the new craft to the Moon, Mars, and beyond have fired the imaginations of scientists and laymen alike. Many say that a near Earth asteroid is the next logical step after the United States’ return to the Moon, sometime before 2020. Others say that an asteroid mission could be taken even before the return to the Moon. They say such a mission could alleviate the “been there, done that” feeling which some detractors love to bring up any time the Vision for Space Exploration is mentioned. The interest has led to a number of articles in space trade news (such as this SPACE.com article) and even in mainstream newspapers such as USA Today, where the classic but overstated “huge asteroid impact” graphic was placed above the fold on page 1, and missions to asteroids were part of the discussion within. Crewed asteroid missions also received a short mention in NASA’s report to Congress on the NEO threat. An asteroid mission is an exciting prospect. Its allure includes the possibility of using less propellants than a lunar landing mission and not requiring the development a separate landing vehicle. The idea of exploring new territory is always enticing and cannot be overlooked, while mission timelines are possible that are on the order of an extended lunar stay, serving as stepping-stones to much longer Mars missions. It turns out that two of the criteria used to argue for an asteroid mission—low propellant use and short timelines—are linked to each other through the mathematical dance of orbit mechanics and the rocket equatio <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

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