gdp's Comments

The Space Review: essays and commentary about the final frontier : The Space Review: Moon and Mars advocates find peace

Tue, 15 Sep 2020 06:50:09 +0000

Gateway isn't necessary, as we have the capability to determine zero-g effects on the human body on the ISS It's not the zero-g effects, it's the full dose of galactic cosmic rays and testing "storm shelter" shielding for (potential) solar proton events. Realistically, SLS/Orion will be ready to fly a lunar mission before SX Starship is wrung out and ready to fly a crew in cislunar space, Starship will be harder and take longer than you think.

The Space Review: essays and commentary about the final frontier : The Space Review: “Artemis 8” using Dragon

Thu, 6 Aug 2020 23:12:57 +0000

"No numbers for the real designed-in deep space radiation protection..." Crew Dragon Capsule dry mass: 9,525 kg Crew Dragon Capsule habitable volume: ‎9.3 m³ Orion CM dry mass: 9,300 kg Orion habitable volume: 9.0 m³ "and propellant mass..." Propellent mass is essentially irrelevant. Orion's SM fuel is separated from the CM by the Crew Module Adapter, and since (at the scale of the s/c) solar protons are isotropic, Orion's CM doesn't get any significant radiation attenuation from the SM fuel. Both s/c have some fuel tanks surrounding their habitable volumes. However, the Crew Dragon's much larger propellant tanks for the SuperDraco Escape system actually surround the "well" in the base of the cabin where the crew would huddle during a CME event. Advantage: Dragon. Again -the improvised radiation shelters in both Orion and Dragon surround the crew on five sides with boxes of supplies, with the sixth side protected by the s/c heat shield. Since the SpaceX Dragon retains its Martian return velocity capability, the Dragon heat shield is a much thicker (better) shield than the Orion's shield. Again: advantage Dragon. This series of comments is ostensibly about Zurbin's "Artemis 8” Lunar mission using Dragon vs. waiting for(ever) for the EM-2 (aka Artemis II) SLS/Orion mission. In reality, the radiation protection offered by these two s/c is very similar, with a slight advantage offered by Dragon's structure. The BIG difference in crew radiation exposure is due to the mission models. The mission model for EM-2 is the comparatively "high risk Russian Roulette Lunar mission" Artemis 8 uses earth orbit rendezvous to assemble the elements, then performs a direct TLI and gets "the hell out of Dodge" rapidly. In comparison, EM-2 (Artemis II) using the sad SLS interim cryogenic propulsion stage will do a double orbit pass through the lower Van Allen radiation belts at 35,000 kilometers. I'm sure the crew will be fine, I'd go without hesitation. James, you don't know what you're talking about -as usual. Draft horses -flogging? What? What are you even doing commenting on The Space Review?

The Space Review: essays and commentary about the final frontier : The Space Review: “Artemis 8” using Dragon

Sun, 2 Aug 2020 05:13:53 +0000

"Your hand waving away a LEO mission design Dragon's spacecraft's inherent radiation shielding didn't offer any direct radiation comparison with the deep space design and inherent radiation shielding of the Orion spacecraft" There's no "hand waving", just the simple facts that anyone can see. The document you linked to, 2016WRMISS-RGaza.pptx (WRMISS 2016) is clear as a bell... to everyone but you. The chart at the top of page 3, SPE Response Scenario, of WRMISS 2016: 2006: -Safe haven partially in the bays -Cabin reconfigured to optimize shielding -216 kg of dedicated radiation shield 2016: -Safe haven completely in the bays -Cabin reconfigured to optimize shielding -0 kg of dedicated radiation shielding (emphasis added) 0 kg. Zero. Zip. Nada. What part of ZERO don't you understand? Really James, what part? As the WRMISS 2016 makes crystal clear in both text and graphics, Orion's "Designed for Exo-LEO, Current baseline improved the crew protection" is the result of added radiation sensors (and their software) plus extra bungee cords. That is it Moon Miner, sensors and extra bungee cords. "LEO spacecraft are not necessarily designed to be beyond LEO spacecraft because to do so would add unwanted mass that is not needed or desirable for LEO missions". As usual, there's unintentional irony in your comments. The original 2006 Orion designed for Project Constellation, was destined for LEO use as crew transport to ISS AND beyond LEO flights to the Moon. But in order to shave weight for the underperforming Ares I re-design, NASA jettisoned that 216 kg of dedicated radiation shielding in the original Orion airframe. In short, the 2006 Orion actually had"...unwanted mass that is not needed or desirable for LEO missions". You are such a rocket scientist James. Bottom line: the not necessarily designed to be a beyond LEO spacecraft SpaceX Dragon, only requires Orion's radiation sensor suite and extra bungee cords to be functionally equivalent to Orion in the crew radiation protection department.

The Space Review: essays and commentary about the final frontier : The Space Review: “Artemis 8” using Dragon

Sat, 11 Jul 2020 06:02:29 +0000

“…Dragon that was designed for short duration missions in the lower LEO radiation environment have the same heavy radiation protection for astronauts as the Orion” Whatever gave you the idea that Orion is designed with some sort of “heavy radiation protection”? In the event that Orion’s crew is caught in a solar proton event (SPE), the plan is to gather up boxes of the ship’s provisions (food, water, clothing, poop, urine etc.) and form a “storm shelter” where the crew can huddle with the boxes on five sides with the s/c heat shield and service module facing the sixth side. Here's a short YouTube clip in which two chipper NASA gals show Orion's rad shielding: https://youtu.be/70GrihLXmSs A lunar mission Dragon crew that’s caught in a SPE, can do exactly the same improvised storm shelter procedure as an Orion crew.

The Space Review: essays and commentary about the final frontier : The Space Review: Orbital use fees won’t solve the space debris problem

Mon, 29 Jun 2020 06:21:40 +0000

Starship could explode: 1) depressurization of one of the main tanks 2) failure of the LCH4 header tank 3) through one tank and through the bulkhead 4) mix in the enclosed tail-to-tail 5) good old fashioned ramming So what. These are not hypergolic propellants, you need an ignition source for a deflagration (not explosion) to occur. So on top of your fantastically unlikely impact event, you have to somehow have an even more unlikely ignition source. This is just more James Moon Loon FUD. Three of Four times a year a Progress s/c with over 3000 lbs of actual hypergolic propellent docks with the enormous ISS in LEO, but I don't see James spouting FUD over the possibility of an accident with that.

The Space Review: essays and commentary about the final frontier : The Space Review: Why a business case for Mars settlement is not required

Mon, 6 Apr 2020 06:38:15 +0000

"Currently, Blue Origin's upcoming New Glenn has a clean and green hydrolox upper stage. Maybe the New Glenn will eventually have a hydrolox first stage, too. Blue Origin's Blue Moon Lunar Lander is also powered by a propellant efficient hydrolox rocket engine…" “clean and green hydrolox upper stage…Blue Moon Lunar Lander ” You bring up hydrolox upper stages a lot James, soooo you’re worried about CO2 polluting outer space and the moon?? Really?? “New Glenn will eventually have a hydrolox first stage, too” NO James, it will NOT eventually have a hydrolox first stage. New Glen, like Vulcan and Star Ship, are clean sheet, modern designs using the ideal fuel for affordable, reusable launch vehicles -methane.

The Space Review: essays and commentary about the final frontier : The Space Review: Why a business case for Mars settlement is not required

Mon, 6 Apr 2020 06:17:19 +0000

"If you knew half as much as you pretend to know, you would know that Japan's upcoming Lunar mission supporting H3 Heavy is a clean and green all hydrolox launcher." The H3 Heavy is fantasy, there is essentially zero chance the Japanese government will fund this extremely expensive development effort for a vehicle with no commercial uses. Liquid hydrogen for Japan’s JAXA launchers is made by the Iwatani Corporation in Sakai. The hydrogen is made from natural gas feedstock using the high-temperature (~2000F) steam-methane reforming process. The Liquid hydrogen made in Sakai, is transported 960 miles to the Tanegashima Space Center by convoys of insulated diesel trucks. The making of hydrogen in the reformers, cooling it to cryogenic temperatures to liquefy it, then hauling to the Space Center is extremely energy and CO2 intensive. A quick back-of-the-envelope calculation shows that from 5 to 7 times more CO2 is put into the atmosphere by your so-called “clean and green hydrolox” launchers than by the new state-of-the-art methane fueled launchers. The 5 to 7 times more CO2 from the Hydrogen fuel does not count the filthy Solid Rocket Boosters that the parallel burn hydrogen launchers need to get off the ground or the huge amount of energy and materials used to manufacture these throw-away rockets. And NO James, steam reforming natural gas is the only source for industrial-scale hydrogen production. Electrolyzing water takes fantastic amounts of electricity and there are NO plans by JAXA, NASA or ESA to invest $billions in electrolysis systems for a few, antiquated, government-subsidized launch vehicles.

The Space Review: essays and commentary about the final frontier : The Space Review: Balancing astronomical visions with budgetary realities

Fri, 17 Jan 2020 01:58:33 +0000

Welp, I'm envisioning the (most likely) sort of failures similar to what happened in 2018 where there were some ≈4" rips and tears with less than taut cables. You, on the other hand, are promulgating a 100%, total failure scenario in order to prove your point. So it goes.

The Space Review: essays and commentary about the final frontier : The Space Review: You can’t take the sky from me

Thu, 16 Jan 2020 17:23:36 +0000

"...attention to tiny numbers of protesters, Well said.

The Space Review: essays and commentary about the final frontier : The Space Review: Balancing astronomical visions with budgetary realities

Thu, 16 Jan 2020 17:16:58 +0000

Sorry, for those in Rio Linda: the propellant for the reaction control thrusters is used to desaturate the momentum wheels. Even if everything goes perfectly with the s/c, the supply of hydrazine is a life-limiting consumable. I would be so painful to see such an expensive, productive "discovery machine", simply run out of gas. This, of course, opens the door to a future servicing mission of sorts. As JWST runs low on propellent, a modified Mission Extension Vehicle (MEV) could dock to the s/c bus and extend its life by providing reaction control.

The Space Review: essays and commentary about the final frontier : The Space Review: Balancing astronomical visions with budgetary realities

Thu, 16 Jan 2020 07:13:02 +0000

"But the unfolding of the sunscreen doesn't go well" No. Webb's coverage is 0.6-28 microns; Yes. Christ, I should have worded this as "The telescope would do most of its observation..." and included documentation. Obviously the telescope's primary science mission would be devastated if the sun shield doesn't deploy, but some observations in the red to yellow end of the visible range could still be done. There is some overlap, at the shorter end of the spectrum, the limitation is the color of the gold plated mirrors. The last time I looked with my lying eyes, I could, in fact, see gold in visible light. If the sunshade malfunctions, the telescope probably could be re-tasked with a lot of Solar System observations, giving that group an unexpected bounty. In science, you mine data wherever you can. Of course, it costs a lot of money for ground support of an asset like JWST, and if the primary science mission is ruined, NASA may well cut its losses and de-commission the s/c. Finally: if Webb were to be left with mostly Solar System observations, that would be quite the irony. The telescope was originally slated for astrophysical observations only, but in the 2005 National Academy Webb re-design "near-death experience", Solar System observing was added to "broaden" the appeal and gain more support for JWST. The additional filters, baffles, and tracking software changes, added dramatically to the cost and complexity. More tracking of fast-moving targets or opportunities like Mars and outer Solar System objects will burn through more propellent than mostly astrophysical observations too, making the powerful astrophysical community unhappy even in the best of times.

The Space Review: essays and commentary about the final frontier : The Space Review: Balancing astronomical visions with budgetary realities

Wed, 15 Jan 2020 02:30:19 +0000

"But the unfolding of the sunscreen doesn't go well" The telescope will do most of its observations in optical wavelengths, while the IR science would suffer. This often happens in space science, one group's misfortune is another group's gain. For instance, when Hubble first launched with its flawed mirror, some astronomers in the High-Speed Photometer teams had a field day with lots of extra observing time, because their observations didn't require a super sharp image.

The Space Review: essays and commentary about the final frontier : The Space Review: The challenges facing Artemis in 2020

Sun, 12 Jan 2020 23:53:25 +0000

"Show us the peer reviewed literature and environmental numbers on the risks..." "Show us the peer reviewed literature on the safety and risk numbers..." "show the peer reviewed "math" and careful LEO environmental risk evaluations" -James Moon Miner What exactly do you want, (in normal grown-up language)? peer reviewed literature peer reviewed peer reviewed... You never offer "peer reviewed literature" to support your endless FUD (fear, uncertainty, and doubt). Are we to assume you belong to AIAA? AAAS? I post a lot on AIAA forums, but I don't recall ever seeing your distinctive, grade-school level, paragraph long run-on sentence style. What gives? There's so many relevant papers, you need to be specific. Bayesian Cloud Extraction for Assessment of Space-Debris Impact Using Conditional Entropy -Kanjuro Makihara and Yoshihiro Oki Journal of Spacecraft and Rockets201754:6, pp. 1235–1245 Solutions to Rapid Collision-Avoidance Maneuvers Constrained by Mission Performance Requirements -Jason A. Reiter and David B. Spencer Journal of Spacecraft and Rockets201855 Optimization of Active Debris Removal Missions with Multiple Targets Hong-Xin Shen, Tian-Jiao Zhang, Lorenzo Casalino and Dario Pastrone Journal of Spacecraft and Rockets201855 Hypervelocity impact in thin sheets and semi- infinite targets at 15km/sec D. SAWLE May 5-9 AIAA/ASCE/AHS/ASCHypervelocity Impact Conference Investigation of Cyclic Behavior and Structure-property Relations of a 304 Stainless Steel Marcos Lugo, Jonathan W. Pegues and Nima Shamsaei 5-9 January 201556th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics Parametric Analysis of Single-Stage Earth-Departure-Stage In-Orbit Refueling -Alessandro A. Golkar and Edward F. Crawley 20 February 2014Journal of Spacecraft and RocketsVolume 51, Issue 2 Computational Design of Metal–Fabric Orbital Debris Shielding Eric P. Fahrenthold Journal of Spacecraft and Rockets201754:5, pp. 1060–1067

The Space Review: essays and commentary about the final frontier : The Space Review: The challenges facing Artemis in 2020

Sun, 12 Jan 2020 07:51:00 +0000

In November 1992, flight rule 2-77 instituted a tail forward, nose down preferred flight attitude; STS-53 was the first Orbiter to fly this orientation with a subsequent decrease of 40%, on average, in the number of windows replaced from 1 per 6 days on orbit (approximately) to about 1 per 9.5 days per orbit.2 Other Orbiter attitudes have also been used for other reasons such as extravehicular activities, payload bay shielding, or ISS protection. These attitudes typically put the base of the Shuttle normal to the v bar (velocity vector). -NASA Orbit Flight Techniques Flight Rule 2-77 Constraining On-Orbit Attitude: Because of the geometry of orbital conjunctions, the shuttle orbiter’s forward-facing (in the direction of the orbiter’s velocity vector) surfaces will be subject to the great majority of collisions with orbital debris. Therefore, the orbiter’s attitude relative to the orbital vector. will have a major influence on the effects of impacts of meteoroids and orbital debris. One of the most significant factors in window replacement, for example, is the length of time that windows face in the direction of the velocity vector (Smith, 1995). Figure 6–1shows how the orbiter’s attitude affects the predicted number of window replacements, and Figure 6–2 shows how the assessed risk of critical penetration (a penetration anywhere on the orbiter that could result in the loss of the orbiter or crew) varies with orbiter orientation. Developers of orbiter attitude time lines take into consideration the possibility of critical damage, damage that would force early termination of a mission, and damage to orbiter windows, and balance the potential for damage against the need to accomplish mission objectives. -Shuttle Flight Rule A2.1.3–32 preferred attitude for orbiter There are many mitigation measures to reduce the probability that collisions with small debris will disable the spacecraft and prevent successful postmission disposal. These measures use the fact that the debris threat is directional (for man-made debris, highly directional) and that the directional distribution can be predicted with confidence. Design responses to reduce failure probability include addition of component and/or structural shielding, re-arrangement of components to let less sensitive components shield more sensitive components, use of redundant components or systems, and compartmentalizing to confine damage -NASA Management Instruction (NMI) 1700.8 In order to protect crews from debris during flight, operational procedures have been adopted. In the case of the Space Shuttle, the orbiter is often oriented during flight, with the tail pointed in the direction of the velocity vector. This flight orientation was adopted to protect the crew and sensitive orbiter systems from damage caused by collisions with small debris. 59. Operational restrictions have also been adopted for extravehicular activities (EVAs). Whenever possible, EVAs are conducted in such a way as to ensure that the EVA crew is shielded from debris by the orbiter. -Technical Report on Space Debris: United Nations Scientific and Technical Subcommittee of the Committee on the Peaceful Uses of Outer Space

The Space Review: essays and commentary about the final frontier : The Space Review: The challenges facing Artemis in 2020

Sat, 11 Jan 2020 06:14:00 +0000

“…small piece of LEO space debris …slams into a thin-skinned 120 tonne dry mass Starship and its 100+ tonne dry mass payload and 1,000+ tonnes of volatile propellant and its hooked up to 120 tonne dry mass and thin-skinned tanker” “…endlessly risky LEO volatile propellant robotic tanker refueling attempts” “…plans for SpaceX's Starship do require it to loiter to be refueled in risky debris rich LEO” ---ad nauseam Sigh. The production version of Starship will have to endure the rigors of atmospheric EDL (entry, decent and landing). The nature of any aerospace vehicle capable of EDL is not egg shell thin and fragile, the Starship airframe must survive the extreme dynamic pressures of entry as well as the mechanical loads of landing. The “belly” of Starship will be covered with durable, reusable thermal protection tiles, and the forward section with the flight deck must be at least as robust as any other manned spacecraft. Starships will conduct LEO operations with either their tile covered bellies, or one spacecraft’s long axis facing into the velocity vector, whichever experience dictates. 1,000+ tonnes of volatile propellant… … volatile propellants …risky LEO volatile propellant robotic tanker refueling …loiter to be refueled in risky debris rich LEO…loiter …loiter…loiter - - -ad nauseam Starship will be fueled by relatively harmless LOX and liquid methane, a punctured tank would just vent the propellant to the vacuum of space, and then the large, low density airframe would deorbit naturally in a few weeks (if it’s totally disabled). Starship is under development, but you know what has already been routinely conducting refueling opps in low earth orbit for the last 22 years? The Russian Progress resupply/tanker for the International Space Station is what. ISS, you know…that big fragile thing in Low Earth Orbit. So tell us Moon Miner, what- every few months do you curl up in a fetal position waiting for the sky to fall whenever a Progress resupply/tanker with its ≈4000lbs of hypergolic fuel “loiters” in LEO with the ISS??

The Space Review: essays and commentary about the final frontier : The Space Review: Nuking Moscow with a Space Shuttle

Thu, 9 Jan 2020 02:39:18 +0000

fleet of robotic, launch on demand, fully reusable, super enormous, vertically landing, and LEO optimized launchers

In other words, in normal adult English, a "fleet of SpaceX Starship/Super Heavy (collectively referred to as Starship)". In your mind, you're oh so coy and clever with your paragraph-long run-on sentences denouncing the Starship, but you're just annoying and weird. Yeah yeah yeah, SpaceX Starship is going to destroy the world because:

A. launch on-demand gliding prompt global strike nuclear weapons and kinetic impactors B. Destroy space travel because of orbital debris from loitering in LEO to refuel causing an explosion C. Destroy the atmosphere because of CO2 polluting and warming the "Home Planet"

As time goes on, fewer and fewer Space Review readers bother to argue with and your bizare rants, mostly because it as hopeless as trying to argue geopolitics with a fourth grader.

The Space Review: essays and commentary about the final frontier : The Space Review: A work in progress

Mon, 16 Dec 2019 19:22:58 +0000

"$1 Billion vehicles winds up at the bottom of the Atlantic" Please - SLS will fly an ascent similar to the Space Shuttle, the SRBs will fall into the Atlantic, but the SLS core will destructively enter half way around the planet over the Southern Indian Ocean.

The Space Review: essays and commentary about the final frontier : The Space Review: Funding Europe’s space ambitions

Sat, 14 Dec 2019 23:15:41 +0000

"Perhaps an Ariane 6 with large reusable boosters similar to the Baikal rocket fly-back booster design but based on a future super extended P120 solid rocket motor stage could significantly increase payload mass performance while helping to reduce costs for the Ariane 6, Vega C, and future ESA launchers."

That’s ridiculous, and full of unintentional irony like most of your posts.

P120 solid rocket motor stage…” there you go again promoting solid rocket motors; Ariane 6, SLS, OmegA, H-IIA –if it’s got filthy "burning tire fire" solid rocket boosters, you love it.

You’re always going on about SpaceX’s “grossly propellant inefficient neoLuddite, CO2 spewing fossil fueled BFR/Starship” bla bla bla. Fossil fueled -right. What the h*ll do you think the propellant (called “grain” in SRBs) is made of? Magic unicorn candy canes?

The solid rockets grain are made of APCP (Ammonium Perchlorate Composite Propellant). The bulk of the grain is a solid synthetic rubber called polybutadiene acrylonitrile (PBAN) that allows it to be cast into the motor cases. PBAN copolymer, has a molecular formula: C15H17N. The butadiene is a byproduct of ethylene steam crackers. The hydrocarbon feedstock for the ethylene steam crackers is ethane, propane, butane, naptha and gasoil. The most energetic components in APCP is a witches brew of atomized aluminum powder, iron oxide with ammonium perchlorate oxidizer. The perchlorate is the worst part of SRB grain, perchlorate per chlorate.

It’s the chlorine in the APCP grain that’s the biggest problem (not to mention the horrible atomized aluminum, iron etc). Chlorine from chlorofluorocarbons (CFCs in your asthma inhaler) and from perchlorate SRB oxidizer, is the most potent ozone depleting chemical in existence. Chlorine is able to destroy so much of the ozone because it acts as a catalyst, chlorine initiates the excessive breakdown of ozone by interfering with the Chapman Cycle in the stratosphere.

The only way to make Ammonium Perchlorate Composite Propellant more harmful to the ozone layer, is by injecting it into the stratosphere together with ice crystals from combusting liquid hydrogen and liquid oxygen in “parallel burn” launch vehicles, like, Ariane 5/6, HII-A and the king of ozone destruction, SLS.

Future “fly-back booster” super extended P120 solid rocket motor stage that’s hilarious. ESA already has a next generation rocket engine program – Prometheus. ESA is concerned with future international regulations to limit solid rocket motor stratospheric pollution, and of course ESA is getting it’s a** kicked by SpaceX’s more affordable prices.

All the major space powers have reusable, METHANE fueled engine programs. They worry about meeting SRB pollution regulations as well competing with the more affordable Vulcan, New Glen and SpaceX launchers. Methane engine programs (in addition to the three big US methalox launchers):

ESA: Prometheus methalox JAXA: “LNG propulsion system” (methalox) Russia: RD-0164 methalox China: TQ-12 methalox

The expendable, ICBM derived kerosene/LOX & N2O4/UDMH launchers, AND the big throw-away, hydrolox government launchers, will become extinct in the early 2020s.

All the great space powers are working toward re-usable, clean, methane fueled boosters.

The Space Review: essays and commentary about the final frontier : The Space Review: Funding Europe’s space ambitions

Sat, 14 Dec 2019 18:10:00 +0000

"The European Space Agency began funding a reusable rocket engine anticipated to be ready for a test-fire demonstration in 2020, the same year as the first launch of the future Ariane 6 rocket. ESA and Airbus Safran Launchers, the 50-50 joint venture between Airbus and Safran that is rebranding as ArianeGroup, signed a contract to develop Prometheus, a liquid- oxygen-and-methane-fueled engine that would cost 1 million euros ($1.1 million) per copy, or a tenth of what Ariane 5’s Vulcain 2 first-stage engine costs to produce." -SpaceNews June 22, 2017