Debris Assessment Software (DAS) analysis
NASA's Debris Assessment Software (DAS 3.2.7) checks a mission against NASA-STD-8719.14, and its results go into the Orbital Debris Assessment Report that accompanies the FCC filing. This page gives our pre-DAS analysis, calibrated against real DAS runs for PROVES 1U satellites, and includes a ready-made DAS project for this spacecraft.
Key finding. A bare 1U at the Transporter-class altitude of 525 km takes about 7 years to reenter. That meets NASA's 25-year requirement but not the FCC 5-year rule (FCC 22-74, applying to satellites launched after 29 Sep 2024). Options:
- A drop-off at or below about 475 km, for example from the rideshare's orbital transfer vehicle.
- A small deployable drag sail. Doubling the area roughly halves the lifetime.
- An FCC waiver argument.
This drives a launch-provider requirement and should be resolved before the ODAR is filed.
Orbital lifetime vs deployment altitude
| Altitude (km) | Baseline (yr) | Solar max (yr) | Solar min (yr) | Face-on area (yr) | FCC 5-yr | NASA 25-yr |
|---|---|---|---|---|---|---|
| 400 | 0.7 | 0.3 | 1.1 | 1.0 | β β€ 5 yr | β β€ 25 yr |
| 425 | 1.1 | 0.4 | 1.9 | 1.8 | β β€ 5 yr | β β€ 25 yr |
| 450 | 2.2 | 0.6 | 3.3 | 3.5 | β β€ 5 yr | β β€ 25 yr |
| 475 | 4.0 | 0.8 | 5.4 | 5.4 | β β€ 5 yr | β β€ 25 yr |
| 500 | 5.7 | 1.2 | 8.8 | 6.7 | β > 5 yr | β β€ 25 yr |
| 525 | 6.9 | 1.7 | 14.2 | 7.8 | β > 5 yr | β β€ 25 yr |
| 550 | 7.8 | 2.3 | 22.7 | 8.9 | β > 5 yr | β β€ 25 yr |
| 575 | 8.9 | 3.2 | 35.8 | 11.2 | β > 5 yr | β β€ 25 yr |
| 600 | 11.0 | 4.5 | 55.5 | 18.4 | β > 5 yr | β β€ 25 yr |
NASA-STD-8719.14 requirements
| Requirement | Description | Status | Basis |
|---|---|---|---|
| 4.3-1 / 4.3-2 | Debris released during normal operations | β Compliant | No planned debris release. The antenna elements stay attached, and the burn-wire line remains captive. |
| 4.4-1 β¦ 4.4-4 | Accidental explosions / intentional breakup | β By analysis | Not evaluated by DAS. The Li-ion cells have a protection IC, back-to-back FETs and a temperature-gated charger. There are no pressure vessels and no propulsion. |
| 4.5-1 | Collision with large objects (< 0.001) | β Compliant (est.) | PROVES Atlas DAS result: 5.6 Γ 10β»βΉ for 0.66 yr at 417 km. Scaled to 7 yr at 525 km with higher flux, it remains below 10β»βΆ, orders of magnitude under the limit. Re-run in DAS. |
| 4.5-2 | Small-debris damage preventing disposal | β Compliant | Passive disposal (atmospheric decay) does not depend on a working spacecraft. |
| 4.6-1 | Disposal within 25 years (NASA-STD-8719.14) | β Compliant | About 7 yr at 525 km and at most 11 yr even at 600 km. |
| FCC 22-74 | Disposal within 5 years of end of mission | β Altitude-dependent | Met for deployment at or below about 475 km (4.0 yr). Not met at 525 km (6.9 yr) without a drag device or a lower drop-off. |
| 4.7-1 | Reentry human casualty risk (< 1:10,000) | β Compliant | PROVES Atlas DAS: every component, including the steel 18650 cans and iron torque rods, demises (68β78 km) with zero casualty area. The LTM adds only fiberglass PCBs and small parts. Re-run with the component list below. |
Model and calibration against DAS
The model integrates circular-orbit decay, da/dt = ββ(ΞΌa)Β·ΟΒ·CDA/m, with CD = 2.2 (as in DAS) and a piecewise-exponential atmosphere blended between solar minimum and maximum on an 11-year cycle (Cycle 25 maximum about 2025.0). A single density scale factor (0.439) was fitted so the model reproduces DAS 3.x lifetimes for the PROVES 1U satellites in The-PROVES-Project-DAS:
| DAS reference case (413 Γ 422 km, 51.6Β°) | DAS (yr) | Model (yr) | Error |
|---|---|---|---|
| Atlas (A/M 0.00969) | 0.660 | 0.664 | +0.6 % |
| Atlas (A/M 0.01468) | 0.422 | 0.423 | +0.2 % |
| Maia | 0.501 | 0.497 | -0.8 % |
| Electra | 0.271 | 0.271 | +0.0 % |
The calibration points are all near 417 km and near solar maximum, so values at 500β600 km through the coming solar minimum are extrapolations. The DAS run itself is the authoritative result.
DAS project for this mission
The site build generates a DAS project folder in the same format as the PROVES DAS repository. Download it, open it in DAS 3.2.7 ("Open Project"), and run Requirements 4.3β4.7.
Orbit inputs: 525 Γ 525 km, 97.5Β°, launch 2027.87. A/M = 0.01348 mΒ²/kg. Update these once the launch provider confirms the deployment orbit.
Reentry component list (Requirement 4.7-1 input)
| Component | Qty | Material | Body | Unit mass (kg) | Dims (m) |
|---|---|---|---|---|---|
| Primary structure (PROVES 1U frame) | 1 | Aluminum 5052 | Box | 0.0920 | 0.1 Γ 0.1135 Γ 0.1 |
| Flight controller (FC V5d LTM) | 1 | Fiberglass | Flat Plate | 0.0446 | 0.09 Γ 0.09 |
| Battery pack board (battery_pack_v2) | 1 | Fiberglass | Flat Plate | 0.0446 | 0.09 Γ 0.09 |
| Li-ion 18650 cells (2S2P) | 4 | Steel AISI 316 | Cylinder | 0.0460 | 0.018 Γ 0.065 |
| AMSAT LTM (3-board PC-104 stack) | 1 | Fiberglass | Box | 0.1300 | 0.092 Γ 0.09 Γ 0.033 |
| LTM harness (J30 to H1/H2) | 1 | Copper Alloy | Box | 0.0100 | 0.02 Γ 0.05 Γ 0.005 |
| Solar panels (XY_Faces_V2a / Z) | 5 | Fiberglass | Flat Plate | 0.0025 | 0.07 Γ 0.09 |
| Solar cells (KXOB101K08TF) | 30 | Fiberglass | Flat Plate | 0.0033 | 0.018 Γ 0.042 |
| Antenna top cap (v2c) | 1 | Fiberglass | Flat Plate | 0.0427 | 0.1 Γ 0.1 |
| Tape-measure antenna elements | 2 | Steel AISI 316 | Flat Plate | 0.0001 | 0.0127 Γ 0.1778 |
| Card brackets | 6 | Aluminum 5052 | Flat Plate | 0.0044 | 0.02 Γ 0.088 |
| L-brackets | 4 | Aluminum 5052 | Flat Plate | 0.0024 | 0.018 Γ 0.035 |
| Feet (PA-12) | 8 | Polyamide | Box | 0.0021 | 0.014 Γ 0.031 Γ 0.007 |
| M2.5 fasteners | 44 | Steel AISI 316 | Cylinder | 0.0003 | 0.00238 Γ 0.01 |
| M2.5 bolts + locknuts | 16 | Steel AISI 316 | Cylinder | 0.0010 | 0.004 Γ 0.01 |
| Wire harnessing | 1 | Copper Alloy | Box | 0.1700 | 0.028 Γ 0.028 Γ 0.028 |
| Torque rod cores | 1 | Iron | Cylinder | 0.0810 | 0.0127 Γ 0.07 |
| Torque rod windings | 2 | Copper Alloy | Cylinder | 0.0040 | 0.005 Γ 0.07 |
| Magnetorquer air coil | 1 | Copper Alloy | Box | 0.2000 | 0.02 Γ 0.0695 Γ 0.016 |
References
- NASA ODPO β Debris Assessment Software Β· DAS 3.2 User's Guide (PDF)
- PROVES Project DAS inputs (Atlas, Electra, Maia, Taygeta)
- FCC 22-74 Second Report & Order β 5-year post-mission disposal rule
Model source: analysis/orbit_lifetime.py, analysis/das_inputs.py.