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IonStorm

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Posts posted by IonStorm

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    2 hours ago, AnTREXon said:

    I hope you don't get in trouble for playing so much KSP  :)

    Although admittedly, I do it at work all the time too. I'm a full time math teacher and convinced my principal to give me free reign in using KSP to teach concepts.

    No, I play on my own time.  And not that much lately.  

    But I compliment your strategy:

    orbital_mechanics.png

    Spoiler

    "To be fair, my job at NASA was working on robots and didn't actually involve any orbital mechanics. The small positive slope over that period is because it turns out that if you hang around at NASA, you get in a lot of conversations about space." https://xkcd.com/1356/

     

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    1 minute ago, Bev7787 said:

    Changed my entry to stock- built a decent Atlas V 411 as well, was also going to do a launch tower as well but gave up on it. I'm testing my replica now.

    Remember nothing is due until actual launch +30 days, so no earlier than October 8.  This allows people to use actual launch audio and to mimic the actual launch timeline, should anyone wish to.  Until then, no entry is considered final.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    6 hours ago, the_Demongod said:

    @IonStorm So how is the fuel tank pressurized in vehicles like this to avoid ullage problems? A membrane that separates the pressurized gas and the fuel? That's the only method I've heard of but I'm definitely no expert in reaction control systems.

    I really can't go into details about the propulsion system https://books.google.com/books?id=P5dBC_JgSLEC&pg=PA67 discusses how it us often done.  This post https://dslauretta.com/2014/12/16/integration-of-the-osiris-rex-main-propellant-tank/ (mentioned several times in this thread) explains much of what you are asking:

    Quote

    The helium tank is a high-pressure (4800 psi) composite overwrapped pressure vessel that supplies helium on demand to the propellant tank. The function of the overwrap is to evenly distribute pressure loads across the entire tank...The helium tank is needed because the OSIRIS-REx propellant system operates in a pressure-regulated mode for our large main-engine burns...For each of our major maneuvers the helium is used to maintain constant pressure in the propulsion system. Prior to the start of one of these burns an upstream latch-valve is opened, ensuring a steady flow of hydrazine to the rocket engines. The latch valve is closed at burn completion. With these regulated burns, OSIRIS-REx achieves a higher thrust. In addition, the precise control of system pressure allows us to accurately predict burn performance and timing prior to maneuver execution. For the maneuvers using the smaller thrusters, OSIRIS-REx operates in “blow-down” mode. In these instances, the latch valve to the helium tank remains closed, and the residual pressure in the main propellant tank is used to flow hydrazine to the rocket engines. This strategy works because the burns are very short, compared to the main-engine burns, and the thrusters use a very small amount of hydrazine.

     

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    5 hours ago, Bev7787 said:

    What are the specs for the thrusters?

    Details on the propulsion system are ITAR controlled, but here is some public information:

    https://dslauretta.com/2014/12/16/integration-of-the-osiris-rex-main-propellant-tank/

    Quote

    OSIRIS-REx propulsion system uses a total of 28 engines that are divided into four groups: a bank of four main-engine propulsion thrusters, six medium-thrust engines, sixteen attitude control thrusters, and two specialized low-thrust rocket engines.

    and https://dslauretta.com/2013/12/03/six-degrees-of-freedom/

    Quote

    The main engines are 200-Newton (N) thrusters directed at the spacecraft center of gravity. A Newton is a unit of force that is equivalent to the gravitational force exerted on a mass of roughly one-quarter of a pound on the surface of Earth.  These engines are used to perform the deep space maneuvers, the asteroid approach braking burn, and the asteroid departure burn.

    In addition, the spacecraft has a set of 22-N Trajectory Control Thrusters that provide attitude control (pitch and yaw) during the large maneuvers described above. These engines also provide thrust to perform smaller trajectory correction maneuvers, which are used to clean up the spacecraft state after the large burns.  Most importantly, two of these thrusters are used to accelerate the spacecraft away from Bennu after sample acquisition.

    The ultimate in spacecraft attitude control is provided by a series of 4.5-N Attitude Control System thrusters. These thrusters are mounted on each corner of the spacecraft and provide full 6-DOF control. They are used for small thrusting maneuvers. In addition, since the reaction wheels continuously build up momentum, these thrusters are fired to remove this momentum in a process called “reaction wheel desaturation” or “taking a momentum dump”.

    One of the most critical maneuvers that OSIRIS-REx will perform is the orbit departure burn leading to sample acquisition. It is essential that we line up the spacecraft orbit and the asteroid rotation with extreme precision, so that we fly over the desired sample site at the right time. For this ultra-fine maneuver, the spacecraft will thrust using a tiny 0.07-N low-thrust rocket engine. Fortunately for us, these engines were just recently developed and qualified for the NASA GOES-R mission.

    Further searching finds http://www.aiaa-space.org/OSIRIS-REx/ which states:

    Quote

    The propulsion system on OSIRIS-REx is a monopropellant hydrazine system “borrowed” from the Mars Reconnaissance Orbiter, the Juno probe that’s scheduled to arrive in orbit around Jupiter on July 4, and Maven, the Mars Atmospheric and Volatile Evolution probe that has been orbiting Mars.

    Additional searching gives http://spaceflight101.com/maven/spacecraft-information/ which states that Aerojet is the vendor for MAVEN.

    5676892_orig.jpg

    A search for GOES-R thrusters comes up with http://www.moog.com/products/thrusters.html as the vendor and a search for Aerojet gives http://www.rocket.com/propulsion-systems/monopropellant-rockets. 

    So other you can study Moog and Aerojet brochures to get all kinds of details.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    23 hours ago, IonStorm said:

    For those striving for spacecraft aesthetic authenticity...

    It may not be obvious, but the red things are remove-before-flight covers as the the plate (with sticker) over OVIRS.  For example in this image you can see the RCS thrusters on the corners are covered in red, there are red lifting eyelets, PolyCam and MapCam have red jackets, and OVIRS has a tan plate with a logo sitcker.  All removed before flight.  Obviously, so is the bag over the SRC at OTES.

    AurO657.jpg

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    4 hours ago, TheUnamusedFox said:

    Rather than go with the cube shape of the actual osiris, I made it egg shaped and rearranged instrument locations.

    So this looks a little like an early OSIRIS concept.  Have fun.

    osiris-2004.png

    https://dslauretta.com/2014/03/06/ten-years-of-spacecraft-design/

    For those striving for spacecraft aesthetic authenticity, here are a couple hundred images (all approved for release).  They are roughly in reverse chronological order of the construction, integration, and testing phase of OSIRIS-REx.

     

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    7 minutes ago, TheUnamusedFox said:

    Dangit! I was hoping to leave off on KSP for a few more months while mods update and bugs get fixed, but I've got to try this. Got to install so many mods, and I don't trust ckan... I'll hopefully be popping back into this thread sometime soon with my mission attempt, failure or not. But first I have to get an RSS install stable with far too many mods ;.;

    Note that any version after 1.0 is permitted, so if you have an older stable build that is fine.  It is also not due until October, so you can still stick to your schedule.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    27 minutes ago, Jetski said:

    @IonStorm it can save you some repetition if you post the rules above on the opening page (in a spoiler tag if it's getting cluttered), plus a the link to grab the RSS and stock version of the Bennu mod. The way the forum pages work here its hard to find stuff without reading every single post in a challenge. 

    My plan exactly.  Once I hear if the rules I created are reasonable.

    28 minutes ago, Jetski said:

    If anyone goes through the trouble to Hyperedit a probe there (as a target to simplify manouvers), share your savegame!  

    Please.  And one for both RSS and stock.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted · Edited by IonStorm
    Edited wet mass requirements for cat1 and KSP version number

    On June 16, 2016 at 0:07 PM, Dman979 said:

    how do you want the thing presented? And in which version of KSP? Are there points for visual mods? DO you want documentation? A design notebook?

    Do you think you could lay out the rules a bit more formally? I like making replicas that are true-to-life, but since this follows engineering principles, I'd rather aim for a balance between accuracy and points here.

    These are good questions and I don't have immediate answers of what is fun, challenging, and reasonable, as my personal experience is messing around in stock KSP and watching Scott Manley and Bob Fitch videos.  

    Categories:

    1. Most accurate spacecraft reproduction in stock KSP with no mods
    2. Most accurate spacecraft reproduction with unlimited use of mods
    3. Most accurate reproduction of OSIRIS-REx mission design in the KSP universe (unlimited mods)
    4. Most accurate reproduction of OSIRIS-REx mission design in RSS/RO (unlimited mods)
    5. Lowest ∆V OSIRIS-REx mission design in the KSP universe to (unlimited mods)
    6. Lowest ∆V OSIRIS-REx mission design in RSS/RO (unlimited mods)
    7. Consolation prize for funniest and most epic fail

    Proof: For 1 and 2 the .craft file (and list of mods for 2) and images are sufficient, but additional explanatory video appreciated. For 3-6 images or a single explanatory video of launch, maneuvers, and each mission phase.  Please read the posts in the thread, http://www.asteroidmission.org, https://dslauretta.com, http://gsfcir.gsfc.nasa.gov/colloquia/4942/touchstone-the-osiris-rex-design-reference-mission, https://www.nasa.gov/mission_pages/osiris-rex/index.html, https://www.facebook.com/OSIRISREx/, https://www.youtube.com/osirisrex, https://www.instagram.com/osiris_rex/, https://plus.google.com/+OSIRISRExMission/posts, https://twitter.com/OSIRISREx, etc. for the details on these phases, the spacecraft, the payload, and the sampling system.

    Limits: KSP version 1.0 or newer is permitted, the most recent version is preferred.  Propulsion systems for 1-4 are chemical and the spacecraft is monoprop.  For 5-6 propulsion systems are limited to those plausibly available (e.g. chemical, ion, nuclear, aerospike, etc.) but not future technologies with no real-world prototype (e.g. no fusion, fission, warp, etc.).  For 5 and 6, mission duration cannot be longer than 15 years.  Low ∆V missions which to not adequately survey Bennu will not be considered. In categories 2-7 all mods/plugins must be listed.  Any custom-made mods/plugins and .craft files must be supplied.  All missions (categories 3-7) must have a launch wet mass of 2110 kg and encounter an object of Bennu's mass and size, such as the one generously created by @KillAshley's Kopernicus.

    Judging: I will judge the fidelity of the submission to the mission and reserve the right to solicit the input of members of the OSIRIS-REx team.

    Are these rules fun and fair?  If so, I'll add them to the front post or accept suggestions to modify them to maximize your entertainment and education.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    1 hour ago, Dman979 said:

    I wonder if it's possible to let us know the times for any midcouse corrections, if there are any. I'd like to match that up, if I can.

    Details are in a presentation by our Deputy Systems Engineer, Ron Mink at http://gsfcir.gsfc.nasa.gov/colloquia/4942/touchstone-the-osiris-rex-design-reference-mission at about 22:45 into the lecture.  The first Deep Space Maneuver (DSM-1) is January 9, 2017.  There is an Earth Gravity Assist (EGA) September 22, 2017.  DSM-2 is November 21, 2017.  

    1 hour ago, Dman979 said:

    Also, if I read correctly, the due date is in September? Is that right?

    I picked launch+30 days as the due date, which puts the due date no earlier than October 8, 2016 (depending on the weather in Florida the previous month).  If that is widely believed to be insufficient, I can be persuaded to extend it

    P.S. Congratulations on going to Philmont.

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted

    35 minutes ago, DaMachinator said:

    From watching the video of the trajectory, it looks like the one-way trip time is about 1.5 years. Is this correct?

    (For my year estimate I was watching Earth's orbit.)

    This schedule from https://dslauretta.com/2015/02/08/the-osiris-rex-heavy-launch-opportunity/ is a bit out of date, but the arrival and departure dates are still accurate, so closer to two years to "arrive."  The definition of arrive depends on if you define it as first imaging by a camera, navigating based on Bennu landmarks, or entering an orbit.  This is between 712 and 826 days in this figure.  (We have since moved around some margin based on solar distance, Sun-Bennu-Earth angle for telecom, and "human factors" aka letting people sleep a little.)  

    A complexity I think ignored by RemoteTech (though I haven't done much outside stock KSP myself) is there are certain positions a spacecraft cannot be in.  Many spacecraft, such as OSIRIS-REx  (or Hubble for that matter) have "keep-out" zones to prevent the cameras and other optical instruments from looking at the Sun and damaging them. Since the OSIRIS-REx high-gain antenna (HGA) is fixed there are orientations where pointing the antenna at Earth also risks pointing the instruments at the Sun.  We do have movable solar arrays (S/A) so the constraint of pointing the HGA at Earth, not pointing the instrument deck at the Sun, but pointing the S/A at the Sun is easier for us.  RemoteTech might handle the problem of the Sun being between the Earth and the spacecraft, I don't recall.

    Good luck!

    heavy-launch-timeline-impacts.png?w=1276

    OSIRIS-REx Asteroid Sample Return

    in KSP1 Challenges & Mission ideas

    Posted · Edited by IonStorm

    Here is a video of the spacecraft being spin-balanced at K(ennedy)SC.  It is critical to keep the center of area and the center of mass at the same spot since the solar pressure close to the force of gravity at Bennu.  For anyone making an OSIRIS-REx model, this should give a nice view.

     

    In the news

    in KSP1 Discussion

    Posted

    1 hour ago, Matuchkin said:

    Did I just seriously get quoted in a NASA article? Thanks for notifying me, @IonStorm.

    And you know what? Is the challenge still up? I'm trying to do it in realism overhaul.

    The challenge is still up. 

    Also, OSIRIS-REx is currently at Kennedy Space Center, ahead of schedule and under budget.

     

     

    In the news

    in KSP1 Discussion

    Posted

    18 minutes ago, Archgeek said:

    Aw man, I never heard about that challenge.  'Would've loved to participate in it.  I'm guessing nukes were off the table for the design? :D

    Its still on:

     

    NASA's OSIRIS-REx

    in Science & Spaceflight

    Posted

    5 minutes ago, insert_name said:

    is the spacecraft going to reenter as well or will it be able to continue exploring 

    Like on Stardust, the SRC is spin-stabalized and ejected from the spacecraft.  The SRC lands at the Utah Test and Training Range (Utah, USA) 8:53 am MDT September 24, 2023, while the spacecraft is diverted into heliocentric orbit.  After that the spacecraft is available to be used as NASA sees fit--though at that point the warranty would have expired :).

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