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The issue of the flight rate for SLS was known even before the rocket was officially announced, with a stuttered start mainly caused by political language.<\/p>\nSpace Launch System (SLS) managers are continuing to look at potential \u2013 and as yet unfunded \u2013 science missions to provide their monster rocket with a viable number of flights. The flight rate dilemma was recently highlighted when it was admitted NASA had looked into \u201chow slow\u201d a launch rate could be viable for the rocket that is expected to make her debut in 2018.
\nSLS Flight Rate:<\/p>\n
As SLS continues to make very good progress during her transition from the design phase to the actual bending of metal at the Michoud Assembly Facility (MAF), the rocket\u2019s projected flight rate remains a huge challenge that needs to be fixed to ensure her immense capability is fully utilized.<\/p>\n
As has been the case for a number of years now, only two missions are currently manifested, while her projected schedule in the 2020s remains threadbare.<\/p>\n
The issue of the flight rate for SLS was known even before the rocket was officially announced, with a stuttered start mainly caused by political language.<\/p>\n
The requirement for debuting SLS in 2017 had little to do with the rocket\u2019s Beyond Earth Orbit (BEO) exploration aspirations. It was the 2010 Authorization Act that called on SLS and Orion to provide a back up role to the Commercial Crew Program \u2013 actually calling for a 2016 operational debut, per the Act \u2013 in the event of a severe delay to what is now known as the USCV-1 (US Crew Vehicle -1) mission.<\/p>\n
Ironically, SLS\u2019 multi-billion dollar strain on the NASA budget has indirectly starved Commercial Crew funding, resulting in USCV-1 slipping to at least the end of 2017. <\/p>\n
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Also adding to the irony was the fact SLS and Orion were never likely to provide such a back up role, due to the obvious requirement the first SLS mission having to be uncrewed for safety reasons. The last time a crew rode on the debut of a NASA vehicle was in 1981, during Columbia\u2019s STS-1 launch.<\/p>\n
Notably, such a SLS and Orion mission to the ISS would have likely cost more money than it would to accelerate the Commercial Crew USCV-1 launch date.<\/p>\n
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The fallout of this political requirement for SLS to launch in 2017 was never solved, even when NASA made it clear Orion had been fully refocused on BEO missions. The result was a four year gap between the debut flight of SLS and the second mission, a flight that will involve a crew for the first time.<\/p>\n
Although this schedule remains the case via public statements by NASA, internally Exploration Mission -1 (EM-1) has slipped to at least the middle of 2018. <\/p>\n
Notably, the slip is specific to Orion\u2019s schedule issues, with some sources noting SLS may still launch in 2017 on a test flight with either a dummy payload or a boilerplate Orion. However, this is just one of several options under consideration.<\/p>\n
What remains the most likely scenario is a 2018 launch of EM-1, with Exploration Mission -2 (EM-2) accelerated to the end of 2020, as continues to be portrayed by internal documentation.<\/p>\n
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As if to convolute matters further, the second flight may change call signs, allowing for another test flight, this time with the powerful Exploration Upper Stage (EUS). Officials have noted it is unlikely they will allow a crew to ride on the new stage until it has been flight tested.<\/p>\n
Also, changing the current EM-2 mission \u2013 a crewed asteroid sample mission \u2013 into the third flight of SLS would make some sense, due to the initial requirement of a robotic mission \u2013 called the Asteroid Redirect Robotic Mission (ARRM) \u2013 to capture the asteroid and place it into an orbit near to the Moon.<\/p>\n
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It is highly unlikely that the ARRM objectives could be achieved in time for the second SLS launch in 2020. However, SLS-2 could be called upon to launch the ARRM spacecraft, as previously suggested by NASA managers.<\/p>\n
Once SLS is into the 2020s, the launch rate should see the rocket launching at least once per year, ramping up to a projected three times per year for the eventual Mars missions. However, the latter won\u2019t be until the 2030s.<\/p>\n
With no missions manifested past the EM-2 flight, the undesirable question of just how \u201cslow\u201d a launch rate would be viable for SLS and her workforce has now been asked.<\/p>\n
\u201cEveryone recognizes that safety issues can be induced with a fast launch rate; however, if the launch rate is too slow, people skills, processes, and equipment can degrade,\u201d as was noted at the latest Aerospace Safety Advisory Panel (ASAP) meeting. \u201cGenerally, there is an optimum launch rate with some limits on \u2018too fast\u2019 or \u2018too slow.’\u201d<\/p>\n
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It was then revealed to the meeting that \u201cThe (SLS) Program has considered this conceptually and has some ideas on how slow is too slow.\u201d<\/p>\n
It is understood that NASA believes one launch every two years is \u201ctoo slow\u201d and over two launches per year is \u201ctoo fast\u201d for missions in the 2020s, based on current SLS production limitations.<\/p>\n
In response, the ASAP encouraged the SLS Program to pursue this question and determine what the boundaries are, before references were once again noted about potential science missions.<\/p>\n
\u201cBudget limits will put pressure on launch rates,\u201d the meeting notes continued. \u201cOne thing that may help the launch rate is the growing interest by the science community in using the SLS for science missions. <\/p>\n
\u201cOne possibility that has arisen is the Europa mission. Missions like this can help fill the gaps and provide a safe and cost-efficient launch rate beyond a human mission to Mars.\u201d<\/p>\n
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Such a mission with a spacecraft bound for the Jovian moon Europa would be an even larger challenge to enable, mainly from a funding standpoint.<\/p>\n
However, it has been on the radar of SLS managers as one of the more steadfast attempts to attract science missions to their manifest, with previous L2 notes showing they have been working alongside the Jet Propulsion Laboratory (JPL) on a notional science mission to Europa. However, this was an exercise, as opposed to the opening plans for an action mission.<\/p>\n
Since then, a Europa mission has continued to be cited in both L2 and public documentation, including the more recent NASA Advisory Council (NAC) overview on SLS\u2019 status.<\/p>\n
\u201cEuropa exploration was identified as a high priority in the \u2018Visions and Voyages\u2019 planetary science decadal survey. SLS can provide direct injection to Jupiter, eliminating several years of planetary gravity assists to reduce flight time to Europa from 6.3 years to 2.7,\u201d noted the latest NAC presentations.<\/p>\n
\u201cAdditional benefits of SLS for Europa Clipper include reduced operational costs, reduced mission risk, and greater mass margin.\u201d<\/p>\n
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Internal evaluations have also placed the Europa mission as a potential addition to the manifest for the SLS Block 1B \u2013 the 105mT version of the Heavy Lift Launch Vehicle (HLV) \u2013 a configuration that is set to dominate the 2020\u2019s SLS manifest and potentially beyond.<\/p>\n
Known as the \u201cThree Degrees Of Freedom (3-DOF) Reference and Loads Trajectories\u201d evaluations, a Design Analysis Cycle (DAC) noted \u201cDesign Reference Missions (DRMs) addressed include the Europa mission configuration (27500),\u201d per L2 notes.<\/p>\n
Incidentally, it also involved two \u201cLunar mission configurations (27002 cargo and 28002 crew),\u201d which sources note is related to any potential change to the current political direction, one that is currently shunning a return to the Lunar surface.<\/p>\n
\u201cTwo loads trajectories (maximum dynamic pressure and maximum acceleration) were also generated for each DRM. The 3 reference and 6 loads trajectories will be presented to the Structures and Environments (StE) Ascent Flight Systems Integration Task Team (AFSITT).\u201d<\/p>\n
Also previously shown to be under evaluation is SLS\u2019 involvement in a Mars Sample Return (MSR) mission.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/11\/Z84.jpg\")
The evaluations depicted, the \u201c2024+ Single Shot MSR on SLS is based on \u201claunch cadence and availability providing a single-shot Mars Sample Return opportunity.\u201d<\/p>\n
This would not be a primary mission for SLS, with the \u201cMars SEP (Solar Electric Power\/Propulsion) Orbiter\u201d riding as a secondary payload. The cited alternatives of using a Falcon Heavy or a Delta IV-Heavy would see it become their primary payload, if selected.<\/p>\n
Based on such a projected timescale for the mission, the opportunity falls into the domain of SLS-5 or SLS-6, should the current manifest remain unchanged.<\/p>\n
Such notional overviews involve Orion being used on the second leg of the mission, picking up the samples in space.<\/p>\n
The idea was again touted in the recent NAC documentation, this time claiming the alternative vehicles would require multiple launches to achieve.<\/p>\n
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\u201cMars Sample Return was identified as a high priority in the \u2018Visions and Voyages\u2019 planetary science decadal survey. SLS offers single-launch option for Mars Sample Return, versus three launches with EELVs,\u201d the NAC presentation claimed.<\/p>\n
\u201cAdditional benefits of SLS for Mars Sample Return include reduced mission time, increased sample mass, and reduced mission cost, complexity and risk.\u201d<\/p>\n
Such claims are repeated for various other notional missions, including large probes to various deep space destinations. However, no such mission will become a reality without funding.<\/p>\n
Officials have yet to note how factoring in the cost of the SLS program impacts on the likelihood of such science missions ever becoming a reality.<\/p>\n
(Images: Via NASA and L2 content from L2\u2019s SLS sections, which includes, presentations, videos, graphics and internal \u2013 interactive with actual SLS engineers \u2013 updates on the SLS and HLV, available on no other site.)<\/p>\n
(L2 is \u2013 as it has been for the past several years \u2013 providing full exclusive SLS and Exploration Planning coverage. To join L2, click here: http:\/\/www.nasaspaceflight.com\/l2\/)<\/p>\n","protected":false},"excerpt":{"rendered":"
Space Launch System (SLS) managers are continuing to look at potential \u2013 and as yet unfunded \u2013 science missions to provide their monster rocket with a viable number of flights. The flight rate dilemma was recently highlighted when it was admitted NASA had looked into \u201chow slow\u201d a launch rate could be viable for the […]<\/p>\n","protected":false},"author":1,"featured_media":30000,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[3718,4011,1659,8075,640,624],"class_list":["post-39521","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-em-1","tag-em-2","tag-europa","tag-eus","tag-orion","tag-sls"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39521"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=39521"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39521\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30000"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=39521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=39521"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=39521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}