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Heavy Lift Launch Vehicle (HLV/SLS) / Re: SLS General Discussion Thread 7

« Last post by DanClemmensen on Today at 04:15 pm »

Sorry, but you are wrong and Ron is right. A single Saturn V launch carried ALL the elements to put 2 humans on the surface of the Moon and return them (and the CMP) safely back to Earth: CSM and the lander.

A single SLS launch will NEVER carry ALL the elements to put humans on the surface of the Moon and return them safely back to Earth. Not even Block 1B or even Block 2 will be capable of doing so. Every proposed lander is either too large or too heavy to be co-manifested with Orion on a Block 1B or Block 2 launch.

And yes, I am quite aware of the fact that the launch vehicle does not actually land the crew on the surface of the Moon. The stuff it carries does that. But that does not change the fact that a single Saturn V launch fully enabled a crewed landing on the lunar surface, whereas a single SLS launch will never enable a crewed landing on the lunar surface.

That feels like an apples-to-oranges comparison, though. The reason the lander won't be co-manifested is more than the difficulties it would cause with SLS: It's also because NASA wants a more capable lander. If you force a lander into the profile of the LM, you're going to get another LM.

I suppose this raises the question, though, of why NASA should bother developing upgrades to the SLS in the first place, when it's only going to be manifested for crewed flights. Adding EUS and BOLE SRB's will allow you to co-manifest...what? Gateway modules? But you could launch those up on a Falcon Heavy for less than the EUS stage alone (let alone its $5-10 billion development price tag!) will cost.

There are only enough leftover Shuttle SRB parts to last through Artemis VIII, so something new is needed anyway. BOLE makes as much sense as anything else unless SLS is terminated before then.

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SpaceX Super Heavy/Starship (BFR/BFS) - Earth to Deep Space / Re: SpaceX Starship/Super Heavy Engineering General Thread 4

« Last post by Lee Jay on Today at 04:11 pm »

Remember that the hold-downs do not have to handle the full thrust of the engines. They have to handle amount by which the thrust exceeds the weight of the object on the launch mount. The highest of those loads would be a Booster without a Ship, IF they static-fire all engines at full thrust. I doubt they would fire the Booster without a full load of propellant.

They also need to handle keeping the thing upright in the wind and that load is highest with both stages stacked.

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Missions To The Moon (HSF) / Re: SLS : Artemis I : Kennedy LC-39B : NET 29 August 2022 (12:33 UTC)

« Last post by Vahe231991 on Today at 04:09 pm »

Why did NASA decide to conduct the rollout for the SLS rocket for the Artemis 1 mission a bit sooner than initially planned?

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SpaceX Super Heavy/Starship (BFR/BFS) - Earth to Deep Space / Re: SpaceX Starship/Super Heavy Engineering General Thread 4

« Last post by darkenfast on Today at 04:08 pm »

Remember that the hold-downs do not have to handle the full thrust of the engines. They have to handle amount by which the thrust exceeds the weight of the object on the launch mount. The highest of those loads would be a Booster without a Ship, IF they static-fire all engines at full thrust. I doubt they would fire the Booster without a full load of propellant.

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SpaceX Missions Section / Re: SpaceX Starship : Superbird 9 : Florida (?) : 2024

« Last post by DanClemmensen on Today at 04:06 pm »

Presuming an estimated launch cost of $160M to GTO by the Starship split between 4 or 5 large GEO comsats. That will be a cheap launch opportunity too tempting for a comsat operator to pass up on.

If my guess is correct. It is terrible news for SpaceX's competitors.

Why would a fully-reusable Starship have a launch cost of $160M? The launch cost should be lower than the cost of an F9 launch. SpaceX has put an enormous amount of money and effort into reducing the cost of a launch. The only reason the cost to the customer would be that high is if SpaceX charges the market price. Once Starship is fully operational, any F9 payload will cost SpaceX less to launch on Starship, except initially Dragon launches. Why go to the administrative, technical, and scheduling trouble of "ridesharing" those comsats? Just launch each one separately.

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Space Policy Discussion / Re: NASA Authorization Bill of 2022

« Last post by yg1968 on Today at 04:04 pm »

See the post below:

Personally I'm skeptical of this concern, especially when it comes from someone like Dan Dumbacher

There's no one in charge of NASA's mega-moon program. And the countdown clock is ticking.

And only now is NASA rushing to create a single management structure to handle it all.

“I keep seeing the pieces of the puzzle but we’re struggling with how the pieces of the puzzle are actually going to fit together and work together,” said Dan Dumbacher, executive director of the American Institute of Aeronautics and Astronautics and the former head of NASA’s Human Exploration and Operations Mission. “There’s a lot of things that have to be figured out.”

Dumbacher, who warned Congress this spring that NASA’s “piecemeal, uncoordinated approach is doomed to failure,” is among a number of agency insiders, veterans and oversight authorities who are sounding the alarm ahead of the maiden launch of the Space Launch System, the biggest rocket ever built, and the Orion capsule that are set to blast off in late August.

As pointed out in the article, the NASA Authorizations bill is forcing NASA to change its structure. For now, NASA has a manager for each Artemis mission but not an Artemis/Moon to Mars program manager. It seems that Congress wants NASA to have a single person in charge of the Artemis/Moon to Mars program. 

Here is what the NASA Authorization bill says:

SEC. 10811. MOON TO MARS. (b) MOON TO MARS OFFICE AND PROGRAM.—
(1) MOON TO MARS OFFICE.—Not later than 120 days after the date of the enactment of this Act, the Administrator shall establish within the Exploration Systems Development Mission Directorate a Moon to Mars Program Office (referred to in this section as the ‘‘Office’’) to lead and manage the Moon to Mars program established under paragraph (2), including Artemis missions and activities.

https://www.congress.gov/117/bills/hr4346/BILLS-117hr4346enr.pdf

NASA said that it would comply with this provision:

President Joe Biden signed the NASA Authorization Act last Tuesday and the space agency says it now intends to overhaul the management structure.

“Yes, it’s in the bill and NASA will comply,” Jackie McGuinness, NASA’s chief spokesperson, told POLITICO.

But even NASA’s biggest boosters aren’t sure it’s enough. Rep. Don Beyer (D-Va.), who chairs the House Space and Aeronautics Subcommittee and co-wrote the NASA bill, says the Artemis program “is an inspiring, ambitious, and monumental initiative.”

“I want NASA to succeed,” he told POLITICO.

But that means instituting a more disciplined approach to “manage moon-to-Mars and its elements in an integrated way,” he said.

Beyer also said he is eager to receive a progress report on the new mandate — but that won’t come until six months from now, long after the planned first Artemis flight.

Incidentally, this is an example of a substantive provision in an Authorization bill that is not directly related to authorizing funding but that has an impact on NASA. So Authorizations bills do matter.

I don't know which approach is better. Jim Free seems to prefer having a manager for each Artemis missions where as Congress prefers a manager for all Artemis missions, i.e., a Moon to Mars program manager. Perhaps a combination of these two approach is possible.

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Heavy Lift Launch Vehicle (HLV/SLS) / Re: SLS General Discussion Thread 7

« Last post by Athelstane on Today at 04:03 pm »

Sorry, but you are wrong and Ron is right. A single Saturn V launch carried ALL the elements to put 2 humans on the surface of the Moon and return them (and the CMP) safely back to Earth: CSM and the lander.

A single SLS launch will NEVER carry ALL the elements to put humans on the surface of the Moon and return them safely back to Earth. Not even Block 1B or even Block 2 will be capable of doing so. Every proposed lander is either too large or too heavy to be co-manifested with Orion on a Block 1B or Block 2 launch.

And yes, I am quite aware of the fact that the launch vehicle does not actually land the crew on the surface of the Moon. The stuff it carries does that. But that does not change the fact that a single Saturn V launch fully enabled a crewed landing on the lunar surface, whereas a single SLS launch will never enable a crewed landing on the lunar surface.

That feels like an apples-to-oranges comparison, though. The reason the lander won't be co-manifested is more than the difficulties it would cause with SLS: It's also because NASA wants a more capable lander. If you force a lander into the profile of the LM, you're going to get another LM.

I suppose this raises the question, though, of why NASA should bother developing upgrades to the SLS in the first place, when it's only going to be manifested for crewed flights. Adding EUS and BOLE SRB's will allow you to co-manifest...what? Gateway modules? But you could launch those up on a Falcon Heavy for less than the EUS stage alone (let alone its $5-10 billion development price tag!) will cost.

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ISS Section / Re: Schedule of ISS flight events (part 2)

« Last post by Salo on Today at 03:55 pm »

https://www1.grc.nasa.gov/space/iss-research/microgravity-research-flights/

Planned Flights
Flight        Date                    GRC Experiment
NG-18      October 2022      SoFIE MIST
SpX-26    November 2022    
SpX-27    January 2023    
NG-19     February 2023    CM-HT SoFIE RTDFS

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SpaceX Super Heavy/Starship (BFR/BFS) - Earth to Deep Space / Re: SpaceX Starship/Super Heavy Engineering General Thread 4

« Last post by tbellman on Today at 03:51 pm »

I'd expect any active hydraulic hold-down latches to disengage sometime before ignition in the launch sequence. Actual lifting of the hold-down clamps would best be accomplished in sequence with the 'hold-up' retraction and QD retraction using a single actuator and linkages. Similar to the Soyuz launch mount: the clamps that hold the booster down are released by the stanchions that hold the vehicle up lifting upwards, which are able to lift when the weight of the booster is removed from them via counterbalance masses, which happens when the engines are ignited and producing greater than 1:1 TWR. Or think 'toggle lock' if you're familiar with firearms breech locking systems.

I don't think you want that.  You would prefer to be able to ignite, verify that all engines actually start and operate nominally, and only then release the rocket.  Otherwise, if there is some problem that causes multiple engines to not start, but enough start to reach e.g. 1.05:1 TWR, the rocket would lift off, but it would not be capable of reaching orbit (too much gravity losses).

Saturn V e.g. was forcibly held down until all five engines were running nominally, and I believe Falcon 9/Heavy is also held down the same way.  (IIRC, the Space Shuttle had frangible bolts or nuts holding it down, that were only released after all three main engines were running nominally; but once the SRBs were lit, there was no return.)

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Missions To The Moon (HSF) / Re: NASA's Artemis Program Updates and Discussion Thread 3

« Last post by yg1968 on Today at 03:50 pm »

Personally I'm skeptical of this concern, especially when it comes from someone like Dan Dumbacher

There's no one in charge of NASA's mega-moon program. And the countdown clock is ticking.

For those of us less acquainted with Dan Dumbacher, what makes his words untrustworthy?

(I do note that the same concern is raised, and has been raised previously, by others, including ASAP (the Aerospace Safety Advisory Panel).)

Dumbacher served as deputy associate administrator of NASA's Human Exploration and Operations Mission Directorate from 2007 to 2014. I guess that the thinking is that he likes a top-down approach with a lot of NASA oversight. The same can probably be said of ASAP. Although Dumbacher recently said that SLS was probably the last of its kind (he thinks that future rockets are likely to be commercial) which was a surprising statement given the role that he played in the development of SLS in the past.

It’s still very early days, but now that SpaceX and others are becoming more advanced, it’s possible that programs like the SLS will be the way of the past. “I think it’s going to be the last rocket that’s done by the government, surely,” Dumbacher says. “With the experience we’ve seen with SpaceX and Blue Origin and emerging space economy, there is no need to go do another launch vehicle the way we started one in 2010.”

https://www.theverge.com/2022/3/17/22978972/nasa-sls-monster-rocket-roll-out-florida-history