Mission Δv Assessment - VALAR Documentation

The Mission Δv Assessment is a free, guided delta-v budget calculator. You enter spacecraft, orbit and maneuver assumptions, and the tool computes a complete, maneuver-level delta-v budget in real time, explaining every line item. No account is needed, and nothing you enter is ever stored. Route: /mission-assessment

Page Layout

The page is a single scrolling workspace: the assessment panels run down the left, and the Mission budget sidebar on the right updates live as you edit. The tool opens with a worked example (a 150 kg satellite with 15 kg of propellant at 550 km) so you always see a complete budget, never a blank screen.

The mission assessment tool: assessment panels on the left and the live Mission budget sidebar on the right

Anonymity Contract

The assessment is anonymous and ephemeral by design. The banner at the top of the page, the sidebar, and the follow-up panel all state the same contract:

The tool runs entirely in your browser — no account, no server round-trip.
“Nothing here is saved” — nothing you enter is stored or sent anywhere.
“Leaving this page means the run is gone.” To keep a completed budget, print it (see Printing the Budget).

There is no save, export, or email action anywhere in the tool — deliberately.

The Assessment Journey

The six numbered panels walk you from assumptions to a finished budget. The budget recalculates live on every keystroke; there is no “calculate” button to wait for.

Stage	Panel	What it collects
01	Spacecraft	Spacecraft name, Dry mass (kg), Initial propellant (kg). A Wet mass metric is shown as you type.
02	Initial orbit	Circular Altitude (km) and Inclination (°). These seed the defaults of new maneuver rows; each maneuver line carries its own altitudes.
03	Maneuver plan	An ordered list of maneuver lines. Add lines with + Add maneuver, reorder with the up/down arrows, duplicate or delete with the row icons.
04	Propulsion	Specific impulse (s). One value applies to every line of the plan.
05	Mission budget	The live budget: every line item, propellant accounting, and totals. No input here — it mirrors your plan.
06	Follow-up	Print the budget, or follow Explore VALAR → to see the operational platform.

Maneuver Types

Each line of the Maneuver plan is one of eight types. Pick the type from the row’s dropdown; the input fields adapt to it. Raising, lowering, and combined lines compute a circular Hohmann transfer, with the plane change folded into the apoapsis burn where it is cheapest. Collision avoidance uses the ESA 200 m dodge-and-return heuristic with a ×2 count margin. Eccentric orbits and natural decay are not modeled.

Type	What it computes	Inputs
Orbit raise (Hohmann)	The two-burn circular-to-circular transfer from the current to the target altitude.	Current altitude (km), Target altitude (km)
Orbit lower (Hohmann)	The same transfer, downward.	Current altitude (km), Target altitude (km)
Plane change	A pure inclination change at the given circular altitude.	Altitude (km), Current inclination (°), Target inclination (°)
Combined raise + plane change	The raise with the plane change folded into the second (apoapsis) burn — cheaper than doing them separately.	Current altitude (km), Target altitude (km), Current inclination (°), Target inclination (°)
Station keeping	A direct Δv allocation, passed through as its own budget line.	Annual Δv (m/s)
Collision avoidance	Per-event Δv for a 200 m dodge and return, multiplied by the expected number of events and a ×2 count margin. The line shows the ×2 count chip.	Altitude (km), Expected CAM count
Deorbit	The perigee-lowering burn from the current orbit toward a disposal perigee.	Current altitude (km), Target perigee altitude (km)
Custom Δv	A direct Δv you specify, for anything the other types do not cover.	Δv (m/s)

Each budget line shows its method name (for example ESA CAM heuristic or Perigee-lowering deorbit), its Δv (m/s), its propellant (kg), and its category: Maneuver or Allocation.

The Live Budget

The Mission budget sidebar mirrors your plan line by line, top to bottom, in plan order.

Element	Description
TOTAL ΔV	The plain sum of every line’s Δv, in m/s. No contingency is added on top.
Line items	One row per maneuver, with the method name, the Δv, the per-line propellant, and the category chip. Collision-avoidance lines carry a ×2 count chip.
Total propellant	The propellant burned by the whole plan (kg). Propellant is sized sequentially: each line burns from the mass the previous line left.
Final mass	The spacecraft mass after the full plan (kg).
Residuals + gauging reserve	A reserve line of 1% propellant residuals + 2% gauging uncertainty on the initial load, per the ESA margin structure. No margin is added to Δv.
envelope v1 / scenario v1	The version stamps of the calculation contract and the worked-example scenario.

When a Calculation Fails

An assumption that cannot produce a budget never fails silently: the tool shows a red, named explanation with a remedy, and the sidebar explains what is missing. Fix the named input and the budget returns immediately.

Failure	What it means	What to change
Invalid input	A value is missing, not a number, or physically impossible (for example a negative dry mass).	Correct the highlighted field; the affected inputs are named in the message.
Outside valid range	A well-formed value sits outside the method’s supported range (for example a deorbit whose target perigee is at or above the current orbit).	Adjust the value back into the maneuver’s supported range.
Not supported	The maneuver needs something the tool does not model — eccentric orbits, natural decay, and similar.	Use a circular-orbit variant of the maneuver, or contact Valar for a full mission analysis.
No change needed	The current and target states are identical, so the maneuver is a valid no-op contributing 0 m/s.	Nothing — this is an explicit zero, not an error.
Something went wrong	An unexpected internal error.	Try adjusting your inputs. If it persists, the tool may have a bug — contact Valar.

Deleting every maneuver line also produces a named explanation (“No maneuvers”) rather than a blank budget — the tool never shows an empty screen.

Printing the Budget

The print path is how you take the budget with you — there is no other export by design.

Build the plan until the Mission budget shows what you want to keep.
Click Print the budget (in the sidebar, or in the Follow-up panel).
In your browser’s print dialog, choose Save as PDF to retain the budget.

The printed page contains only the budget: every line item with method names and categories, the propellant accounting, the reserve, and the totals — no input controls, no navigation. If the current assumptions fail to compute a budget, the printed page shows the named failure explanation instead, so even a failed state is worth keeping.

The print projection: the completed budget without controls or site navigation

The print workflow uses your browser’s print dialog — the layout is already prepared for it. Nothing is uploaded to produce the PDF.

Burn Plan: turn assessed maneuvers into an operational burn plan inside the platform.
Maneuver Import: bring maneuvers from third-party tools into VALAR.
Conjunction Computation: the operational counterpart to the assessment’s collision-avoidance reserve.

​Page Layout

​Anonymity Contract

​The Assessment Journey

​Maneuver Types

​The Live Budget

​When a Calculation Fails

​Printing the Budget

​Related Pages

Page Layout

Anonymity Contract

The Assessment Journey

Maneuver Types

The Live Budget

When a Calculation Fails

Printing the Budget

Related Pages