Moving Hubble to 51.6 degrees (near ISS)

Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

(Explorer8939) wrote in message . com...
Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

I just want to put some numbers out and see how they compare with more
authoritative answers, to see if I have the right idea about orbital
maneuvering, vectors, etc.

I figured an even 17500mph orbital velocity, which isn't exactly
correct, but...

I calculated 7000mph (3132m/s) was needed for the inclination change.
Figuring 11000kg for the Hubble (10863kg rounded up) and 2000kg dry
mass for the booster that would move Hubble...you'd need about 23000kg
of fuel.

And now I await many corrections.

Mike Miller, Materials Engineer

(Explorer8939) wrote in message . com...
Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

Hi,

A quick rule of thumb I heard for plane changes is "for each
60-degrees in inclination change, the delta-V is equal your orbital
velocity!"

I'm doing this on a Saturday afternoon so double check my
calculations...

This is a simple plane change. The angle through which you want to
move the inclination is (51.6 minus 28) = 23.6 degrees.

The equation for delta-V is given by:

delta-V = 2 * V * SIN (angle/2)

For 600 km circular orbit, the circular velocity is about 7558 m/s.

This gives a delta-V = 2 * (7558) * SIN (23.6/2)

delta-V = 3091 m/s.

To compute propellant, you'll need the mass of Hubble plus the
projected dry mass of the add-on "stage" that will do the thrusting
(Hubble doesn't have a propulsion system)

Hubble is about 11600-kg.

If we assume a 2000-kg dry mass for the "stage," then the total dry
mass for the telescope plus "Stage" is 13600-kg. (We may have to
interate a bit to get a better guess for the stage dry mass once we
estimate the propellant needed.)

Then we apply the rocket equation to compute the amount of propellant
needed, given your Isp.

M_prop = ( e^( delta-V/g/Isp) -1) * M_dry

M_prop = ( e^( 3091 / 9.81 / 300) -1 ) * 13600

M_prop = 25316 kg

Ouch.

And that is assuming a Mass Ratio of about 92% for the upper stage,
which is probably a little aggressive. That 2000 kg estimate might be
a little light.

Patrick,

(Patrick Marsden) wrote in message . com...
(Explorer8939) wrote in message . com...
Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

Heck,

Since the hubble is already in orbit, you could easily move it with a
solar powered electric propulsion package, having an Isp of 100,000 or
something.

You could move it with a less than 100 kg ion engine add-on. I haven't
actually worked out the numbers but I know that we have ion engines
that have been flight tested and the Hubble already has solar panels
in place. We don't care if it takes a year to get to the new orbit.

Zoltan

I worked out the numbers:

Assuming an ion engine with a thrust of 1 N (about a 5th of a pound)
it would take about a year to move the Hubble and the propellant mass
would be about 40kg. The electrical power used would be 100kW

Zoltan

Zoltan Szakaly wrote:

(Patrick Marsden) wrote in message . com...

(Explorer8939) wrote in message . com...

Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

Heck,

Since the hubble is already in orbit, you could easily move it with a
solar powered electric propulsion package, having an Isp of 100,000 or
something.

You could move it with a less than 100 kg ion engine add-on. I haven't
actually worked out the numbers but I know that we have ion engines
that have been flight tested and the Hubble already has solar panels
in place. We don't care if it takes a year to get to the new orbit.

Zoltan


Out of curiousity, how would you attach the engine to
Hubble?

(Zoltan Szakaly) wrote in
m:

I worked out the numbers:

Assuming an ion engine with a thrust of 1 N (about a 5th of a pound)
it would take about a year to move the Hubble and the propellant mass
would be about 40kg. The electrical power used would be 100kW

Hubble's solar panels provide about 5.27 kW.

100 kW is more electrical power than ISS has at Assembly Complete. That's a
lot of solar arrays.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

Why glue of course : ). The HST has docking points to be held on to by
the Shuttle's arm, and these are designed to take fairly large loads
used to maneuver the telescope for servicing. A more difficult problem
is that I do not think the HST has a "cigar lighter plug" on it to allow
a connection to its power system. Most of the electrical system is
internal with very secure connectors designed to be worked on by hand.
Any maneuvering vehicle would have to supply all of it's own power and
propulsion.
Does someone know what the delta-v is required to change orbital plane
from the HST orbit to the 56 degree space station orbit?


In article ,
Charles Buckley wrote:

Zoltan Szakaly wrote:

(Patrick Marsden) wrote in message
. com...

(Explorer8939) wrote in message
e.com...

Anyone know the delta-V to move Hubble to 51.6 degrees (while keeping
it near 600 km altitude). What would be the amount of required
propellant, assuming a 300 sec ISP engine?

Heck,

Since the hubble is already in orbit, you could easily move it with a
solar powered electric propulsion package, having an Isp of 100,000 or
something.

You could move it with a less than 100 kg ion engine add-on. I haven't
actually worked out the numbers but I know that we have ion engines
that have been flight tested and the Hubble already has solar panels
in place. We don't care if it takes a year to get to the new orbit.

Zoltan


Out of curiousity, how would you attach the engine to
Hubble?

"Jorge R. Frank" wrote in message
...
(Zoltan Szakaly) wrote in
m:

I worked out the numbers:

Assuming an ion engine with a thrust of 1 N (about a 5th of a pound)
it would take about a year to move the Hubble and the propellant mass
would be about 40kg. The electrical power used would be 100kW

Hubble's solar panels provide about 5.27 kW.

100 kW is more electrical power than ISS has at Assembly Complete. That's
a
lot of solar arrays.

And if you added that many, a) your mass goes up and b) your drag goes up.




--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Jorge R. Frank" wrote in message ...
(Zoltan Szakaly) wrote in
m:

I worked out the numbers:

Assuming an ion engine with a thrust of 1 N (about a 5th of a pound)
it would take about a year to move the Hubble and the propellant mass
would be about 40kg. The electrical power used would be 100kW

Hubble's solar panels provide about 5.27 kW.

100 kW is more electrical power than ISS has at Assembly Complete. That's a
lot of solar arrays.

Then let's move ISS to Hubble!

Just kidding ;-P

But I wouldn't mind if ISS went to more launch-friendly latitudes...
If only russia could launch Soyuz from French Guyana...