If Momentus was working it would show up in the TLE. From what I've
seen there was one tick in the decay of Vigoride 5, but it was a brief
boost of less than 1km, not incompatible with venting a tank of water.
They also didn't bother to mention that their first flight didn't work
at all before they went public; in general their announcements suggest
that they should be read with enhanced skepticism. It is unfortunate
to see Chris Hadfield shilling for them.
On Wed, Apr 19, 2023 at 5:38 AM George Herbert <george.herbert@xxxxxxxxx> wrote:
On Apr 18, 2023, at 5:40 PM, Jake Anderson <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
I have a feeling someone (perhaps SpaceX) will make a high performance "upper
stage" for starship.
"Old school" rocketry style probably H2/O2 maximal mass fraction kinda deal.
Take the relatively benign ride up to LEO for minimal $ on a starship then do
a whole mess of plane changes etc and kick out ride share passengers along
the way into pretty much whatever orbits they want.
Or strap deep space payloads to the top of it and get to Jupiter in less than
a decade.
(I have the feeling the latter payloads are what would fund the development)
Some back of the envelope numbers, assuming the cargo stretched version of
starship exists you have a payload volume (for the cylindrical part only, ex
the nose cone) of 8m diam x 20m long. Thats 1000 cubic meters.
At 70kg/cubic meter that's 70 tonnes of hydrogen in LEO. Add 11 tonnes of
oxygen for a 6:1 ratio and you have 81 tonnes of propellant.
At 95% mass fraction (because why not, we are dreaming and starting in LEO
means we can cheat) and an ISP of 450, you have 13.5Km/s to play with there.
Add a 20Tonne payload and you're at 6.5Km/s. That's a lot of ride share
satellites in a lot of orbits.
LEO really is half way to anywhere lol especially if it's cheap.
On 17/04/2023 3:52 pm, Bill Bruner wrote:
A Transporter style rack on Starship will threaten the business models for
all of the expendable and partially expendable artillery rockets - whether
they are small, medium or large.
"Threaten" might be an understatement.
One example could be Momentus with their microwave water plasma thruster and
solar electric power source.
There are several others in play as well.
Apparently Momentus flew the latest thruster on Transporter 6 in January, so
it’s moving. But I haven’t seen technology reports from that.
-george