SpaceX Falcon Heavy : PPE/HALO : LC-39A : NLT September 2027

[sdsds]

Following vibration testing, Dream Chaser will be moved to the propulsion facility for thermal vacuum testing to simulates the environment the spacecraft will encounter during its mission to the @Space_Station
.

This seems to imply the propulsion facility vacuum testing chamber is available. Is it reasonable to conclude the SpaceX extra-long fairing is no longer occupying that chamber?

[sdsds]

For reasons outlined elsewhere I would dearly love to see a plausible rationale supporting the notion that after launch on FH the co-manifested PPE+HALO can promptly (i.e. with chemical propulsion) get itself onto a trajectory outside the Van Allen belts, after which the solar-electric propulsion can begin the climb towards NRHO.

The reported 18 t mass of PPE+HALO makes it a bit difficult to estimate the kinds of orbits to which FH could deliver it. Linear extrapolation from LSP ELV performance data points yields a C₃ of -10.1. That might for example be a delivery orbit with perigee radius of 19,000 km and apogee radius of 60,000 m. At apogee a spacecraft would need 790 m/s of Δv to circularize its orbit at 60,000 km. That doesn't seem realistic even with optimistic bi-propellant Iₛₚ of 270 s. (It looks like 4.6 t of propellant would be required.)

Is there a rationale supporting a more optimistic C₃ value than that for FH delivery of 18 t?

[Jim]

For reasons outlined elsewhere I would dearly love to see a plausible rationale supporting the notion that after launch on FH the co-manifested PPE+HALO can promptly (i.e. with chemical propulsion) get itself onto a trajectory outside the Van Allen belts, after which the solar-electric propulsion can begin the climb towards NRHO.

It is using electric first.  Chemical is for around the moon.

[sdsds]

It is using electric first.  Chemical is for around the moon.

Thanks for that!

I'm still hoping the initial Gateway gets outside the Van Allen belts relatively soon after launch. My hyper-optimistic thought would be that FH could get 18 t to a C₃ of -3.5. A highly elliptical orbit with perigee radius around 6,600 km and apogee radius around 221,000 km might be an example of this.

That might take the Gateway out far enough that Earth-Moon three-body effects ballistically raise the perigee relatively quickly, with the electric propulsion helping too of course.

[sdsds]

Still chipping away at this....

Apparently it is a well known result that to optimally increase the altitude of an orbit thrust should be directed tangent to the current trajectory, and that doing this continuously at low thrust increases the semi-major axis without changing the eccentricity of the orbit. So just as an example, if FH launched the spacecraft into a roughly 6,800 x 72,400 km orbit (with perigee height about 460 km) its SEP cruise/climb would eventually reach an orbit roughly 29,000 x 307,000 km. At that apogee it would come close enough to the Moon that chemical propulsion might be used to make the lunar transfer.

Or at least something like that?

[sdsds]

EDIT: Strikethrough based on incorrect spreadsheet.

Further, it appears for orbits with that eccentricity the Δv required for the transfer is only ~6.6% more than that required for a classic two-impulse Hohmann transfer. And based on reported values for PPE+HALO the cruise/climb would take only 104.5 days.

That's based on a (possibly faulty) understanding of Equation 27 in the paper cited below, and on AEPS values reported in https://ntrs.nasa.gov/api/citations/20180001297/downloads/20180001297.pdf.

An even more eccentric orbit might do even better. With a cruise phase that short the PPE+HALO project has plenty of time to prepare for launch, and still arrive in the cis-lunar vicinity well before the Artemis IV Orion....

--
Analytical solutions for low-thrust orbit transfers
Marilena Di Carlo · Massimiliano Vasile
Published online: 14 July 2021
https://doi.org/10.1007/s10569-021-10033-9

[spacenuance]

Per Amit Kshatriya, deputy associate administrator, Moon to Mars Program on the Artemis update media conference (Jan 9, 2024), this launch is no longer targeted for October 2025, and will launch sometime later "when it makes sense" in relation to supporting Artemis IV. A NET date will be announced in the near future in coordination with commercial partners. The stack takes about 12 months after launch to get to NRHO.

[deltaV]

So what could SpaceX practically do to increase payload, assuming the FH is already fully expendable?

Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship? Just Starship may not have enough performance but if you add a kick stage or propellant transfer Starship leaves expendable Falcon Heavy in the dust. For example the Helios kick stage website claims it's compatible with Starship. I don't know official numbers for Starship + Helios but my back of the envelope calculations suggest around 37 tonnes to TLI, which is about twice the needed mass to a harder orbit than needed. With this much performance one could probably skip the planned electric propulsion phase and deliver to NRHO solely chemically, saving about a year of flight time.

[gongora]

This program is well over $1B.  Whatever it launches on needs to be certified.  Helios isn't flying until 2026.

[DanClemmensen]

So what could SpaceX practically do to increase payload, assuming the FH is already fully expendable?

Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship? Just Starship may not have enough performance but if you add a kick stage or propellant transfer Starship leaves expendable Falcon Heavy in the dust. For example the Helios kick stage website claims it's compatible with Starship. I don't know official numbers for Starship + Helios but my back of the envelope calculations suggest around 37 tonnes to TLI, which is about twice the needed mass to a harder orbit than needed. With this much performance one could probably skip the planned electric propulsion phase and deliver to NRHO solely chemically, saving about a year of flight time.

NASA is already committed to using Starship with propellant transfer as part of Artemis, and on the current schedule this occurs at least twice (HLS Demo and Artemis III) prior to the PPE/HALO mission. It's hard to see why NASA would balk at using this for PPE/HALO. Worst case: expendable SS with propellant transfer. Probably still about as cheap as the FH.

This assumes Starship works at all, but Artemis is already assuming this.

[Jim]

So what could SpaceX practically do to increase payload, assuming the FH is already fully expendable?

Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship? Just Starship may not have enough performance but if you add a kick stage or propellant transfer Starship leaves expendable Falcon Heavy in the dust. For example the Helios kick stage website claims it's compatible with Starship. I don't know official numbers for Starship + Helios but my back of the envelope calculations suggest around 37 tonnes to TLI, which is about twice the needed mass to a harder orbit than needed. With this much performance one could probably skip the planned electric propulsion phase and deliver to NRHO solely chemically, saving about a year of flight time.

no.  Starship does not exist as far as HALO/PPE is concerned.

[Jim]

It's hard to see why NASA would balk at using this for PPE/HALO.

That would be wrong.

[Robotbeat]

So what could SpaceX practically do to increase payload, assuming the FH is already fully expendable?

Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship? Just Starship may not have enough performance but if you add a kick stage or propellant transfer Starship leaves expendable Falcon Heavy in the dust. For example the Helios kick stage website claims it's compatible with Starship. I don't know official numbers for Starship + Helios but my back of the envelope calculations suggest around 37 tonnes to TLI, which is about twice the needed mass to a harder orbit than needed. With this much performance one could probably skip the planned electric propulsion phase and deliver to NRHO solely chemically, saving about a year of flight time.

NASA is already committed to using Starship with propellant transfer as part of Artemis, and on the current schedule this occurs at least twice (HLS Demo and Artemis III) prior to the PPE/HALO mission. It's hard to see why NASA would balk at using this for PPE/HALO. Worst case: expendable SS with propellant transfer. Probably still about as cheap as the FH.

This assumes Starship works at all, but Artemis is already assuming this.

From NASA’s perspective, Gateway is like a backup near term destination in case HLS is delayed. Additionally, Starship is NOT a proven and reliable launcher and it might be a few years until large payloads can be deployed from it.

So, no.

[gongora]

Realistically, Starship wouldn't be certified for payloads like that for a couple years if it makes orbit soon, and a kick stage flying for the first time in 2026 would probably need a year or two also assuming it's sucessful.  So something like that wouldn't be a contracting option until at least 2027-2028.  Of course Gateway could eventually slip that far, but changing the launch contract right now isn't going to happen.

[DanClemmensen]

So what could SpaceX practically do to increase payload, assuming the FH is already fully expendable?

Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship? Just Starship may not have enough performance but if you add a kick stage or propellant transfer Starship leaves expendable Falcon Heavy in the dust. For example the Helios kick stage website claims it's compatible with Starship. I don't know official numbers for Starship + Helios but my back of the envelope calculations suggest around 37 tonnes to TLI, which is about twice the needed mass to a harder orbit than needed. With this much performance one could probably skip the planned electric propulsion phase and deliver to NRHO solely chemically, saving about a year of flight time.

NASA is already committed to using Starship with propellant transfer as part of Artemis, and on the current schedule this occurs at least twice (HLS Demo and Artemis III) prior to the PPE/HALO mission. It's hard to see why NASA would balk at using this for PPE/HALO. Worst case: expendable SS with propellant transfer. Probably still about as cheap as the FH.

This assumes Starship works at all, but Artemis is already assuming this.

From NASA’s perspective, Gateway is like a backup near term destination in case HLS is delayed. Additionally, Starship is NOT a proven and reliable launcher and it might be a few years until large payloads can be deployed from it.

So, no.

OK, if you think an SLS/Orion mission without a landing (after Artemis II) is a good idea, then you have a justification for Gateway. This is to me an admission that Artemis is primarily just a big jobs program. I personally feel that this is a complete waste of resources, but I'm not the decision-maker. I think the only justification for Gateway is to support Orion for HLS missions longer than a week. This is especially true of the minimal PPE+HALO gateway.

The original question I addressed was "Is NASA desperate enough to solve PPE/HALO mass growth to consider launching PPE/HALO on Starship?" My uneducated response was that an expended SS could be used. This is not a sophisticated EDL-capable chomper. IMO it is probably a smaller SS modification than the modification from SLS block 1 to SLS block 1B.

[Robotbeat]

From NASA's perspective, the point of Gateway isn't really to support lunar missions (regardless of what the PR says) but instead to act as a sort of subscale demo of a Mars Transfer Vehicle or, more generally, a Deep Space Transport. Think the Obama-era Flexible Path. So even without lunar surface missions at all, there's some value in doing Gateway-only missions to buy down risk and mature operations for MTV/DST-like missions.

[Zed_Noir]

From NASA's perspective, the point of Gateway isn't really to support lunar missions (regardless of what the PR says) but instead to act as a sort of subscale demo of a Mars Transfer Vehicle or, more generally, a Deep Space Transport. Think the Obama-era Flexible Path. So even without lunar surface missions at all, there's some value in doing Gateway-only missions to buy down risk and mature operations for MTV/DST-like missions.

My Emphasis in bold.

Diminished value for the MTV/DST concept after the Interplanetary Transport (Starship predecessor) reveal with the progress of the Starship program and zil funding for a pricey MTV program.

At this point NASA either go with Starship to Mars and beyond or be serious with their it will happened in the future Mars DRM archetiture. The clock is ticking down.

[sdsds]

The clock is ticking down.

Yes, the Mars mission clock is ticking. It has been ticking for 55 years or more, and hasn't stopped. Based on that we can be reasonably confident it will continue ticking for years to come, absent some exogenous disruption.

Gateway, starting with PPE+HALO situated in NRHO, keeps the old-school-style Mars planning gears in motion.

[DistantTemple]

Realistically, Starship wouldn't be certified for payloads like that for a couple years if it makes orbit soon, and a kick stage flying for the first time in 2026 would probably need a year or two also assuming it's sucessful.  So something like that wouldn't be a contracting option until at least 2027-2028.  Of course Gateway could eventually slip that far, but changing the launch contract right now isn't going to happen.

Many other rockets seem to be qualified for various categories of launches after several MISSIONS. How come then several people are posting that Starship would need a year or two. Similarly Helios, should need a few launches rather than a number of years. Tom Muller (ex SpaceX(2nd employee) legendry designer of the Merlin engine, founder of Impulse space, which is developing the said Helios) in a recent talk explained that he largely continued the SpaceX attitude to speedy development etc. Assuming Starship reaches orbit soon, getting two or three demo flights of  Helios before 2026 doesn't seem a tall order! (I am not a space professional!)
Edit: Given Tom Mullers history with SX, and the synergy of a kick stage with Starship, good cooperation between Impulse Space and SpaceX for early qualification flights would make outstanding sense, especially if they also predict Halo's use for Gateway!

[DanClemmensen]

From NASA's perspective, the point of Gateway isn't really to support lunar missions (regardless of what the PR says).

If I'm not supposed to  believe what NASA says, then how should I decide who to believe instead?