SAKHACUBE-CHOLBON

SAKHACUBE-CHOLBON

SAKHACUBE-CHOLBON is a small spacecraft developed and built as part of a joint project with the Sakha Science Academy to launch the first Sakha satellite. The spacecraft purpose is to perform educational and scientific research tasks, as well as to test the ground support infrastructure.

The spacecraft carries a YKSA LLC payload with 12 Arduino-compatible microcontrollers and a set of sensors to study the environment. School students of the Sakha Republic will be able to upload programs to the spacecraft and conduct their own research.

The spacecraft also performs an amateur radio mission. Telemetry and images from the onboard camera, SSTV postcards, audio messages, and other data will be transmitted. Communications are performed in the 437-439 MHz amateur radio band.

The project is supported by the Trust Fund for Future Generations of the Republic of Sakha (Yakutia).

Overview

Name	МКА «Чолбон»
Catalog name	SAKHACUBE-CHOLBON
Bus	SXC1 by SPUTNIX LLC
Payload	YktSat EDU/16 PC/104
Owner	Sakha Science Academy Nonprofit organization «Trust Fund of Future Generations in the Republic of Sakha (Yakutia)»
Operator	Sakha Science Academy, YKSA LLC (technical guidance)
Manufacturer	SPUTNIX LLC, YKSA LLC
Project status	Handed over to the launch provider
Launch date	Expected Dec 15, 2025 Rideshare (secondary) payload with Aist-2T
Launch site	Vostochniy Cosmodrome, Russia
Expected mission duration	3 years, extension up to 9 years

Spacecraft is operated via ground stations of the YKSA GSN service. Communications are performed in the 437-439 MHz amateur radio band.

Primary ground station: 678011 Republic of Sakha (Yakutia), Khangalassky district, Chapaevo village, G. Savvina St., 1, Sakha Science Academy.

Technical specifications

Mass and dimensions

Table 1. Mass and dimensions of SAKHACUBE-CHOLBON
Parameter	Value
Form factor	CubeSat, 1U
Dimensions (by rails)	100 x 100 x 113.5 mm
Dimensions (not exceeding)	108 x 108 x 113.5 mm
Mass	1211 g

Onboard equipment

Onboard equipment includes the following components:

YktSat EDU/16 PC/104 payload — 1 pcs.
UHF antenna with separation system SXC-AUH-03 — 1 pcs.
UHF transceiver SXC-UHF-02 — 1 pcs.
Electric Power System (EPS) SXC-PSS-03 — 1 pcs.
Battery pack SXC-BAT-03 — 1 pcs.
Flight computer SXC-MB-04-RPI — 1 pcs.
Camera SXC-CRPI-01 — 1 pcs.
Solar panels with GaAs solar cells and integrated mmagnetorquers (side) SXC-SGS-03 — 4 pcs.
Solar panels with GaAs solar cells and integrated magnetorquers (end) SXC-SGE-03 — 2 pcs.

Attitude determination and control system (ADCS) includes magnetorquers integrated into solar panels; magnetometer, gyroscope, and accelerometer for attitude determination. Attitude control accuracy is +/-20° on all axes.

Payload includes 12 Arduino-compatible microcontrollers; CsI(Tl) scintillation gamma spectrometer; temperature sensors; multispectral light sensors on each axis; camera. Detailed specifications of the payload are available by the link YktSat EDU/16 PC/104.

Energy budget

Table 2. Energy budget of SAKHACUBE-CHOLBON
Parameter	Value
Average power consumption	1.11 W
Peak power consumption	5.00 W
Battery capacity	39.00 Wh
Average available payload power	0.50 W
Total solar cell output power average, at least	1.50 W

Radio link

Table 3. Downlink radio link budget (Spacecraft—Ground)
Parameter	Value
Transmitter power, Ptx	2.0 W (3.0 dBW)
Transmitter antenna gain, Gtx	0.1 dBi
Receiver antenna gain, Grx	12.8 dBi
Propagation losses, Lp	152.9 dB
Transmitter antenna losses, La_tx	3.5 dB
Receiver antenna losses, La_rx	3.1 dB
Receiver signal level, Psrx	-145.4 dBW
Effective noise temperature of the ground station, T	468 К (-16.3 dB/K)
Receiver noise level, Pnrx	-158.9 dBW
Boltzmann constant, k	-228.6 dBW/Hz
Required bit energy to noise power ratio	6.5 dB
Data rate in the channel	9600 bps (39.8 dBW/Hz)
Signal-to-noise ratio (SNR)	+13.5 dB
Link energy budget	7.0 dB

Table 4. Uplink radio link budget (Ground—Spacecraft)
Parameter	Value
Transmitter power, Ptx	10.0 W (10.0 dBW)
Transmitter antenna gain, Gtx	12.8 dBi
Receiver antenna gain, Grx	0.1 dBi
Propagation losses, Lp	152.9 dB
Transmitter antenna losses, La_tx	3.1 dB
Receiver antenna losses, La_rx	3.5 dB
Receiver signal level, Psrx	-138.1 dBW
Effective noise temperature of the spacecraft, T	385 K (-27.9 dB/K)
Receiver noise level, Pnrx	-159.7 dBW
Boltzmann constant, k	-228.6 dBW/Hz
Required bit energy to noise power ratio	8.0 dB
Data rate in the channel	9600 bps (39.8 dBW/Hz)
Signal-to-noise ratio (SNR)	+21.6 dB
Link energy budget	13.6 dB

Orbital information

Table 5. Preliminary orbital parameters of SAKHACUBE-CHOLBON
Parameter	Value
Orbit type	Sun-synchronous orbit (SSO)
Inclination	97.5°
Altitude	550 km
Orbital period	95.5 min
Local time of ascending node (LTAN)	22:30

TLEs are not available at the moment.

Amateur radio

SAKHACUBE-CHOLBON uses standard SPUTNIX data transmission protocols. Technical information about the radio link is available on the SPUTNIX website. Communications are performed in the 437-439 MHz amateur radio band.

Telemetry and images from the onboard camera, SSTV postcards, audio messages, and other data will be transmitted. Details will be published on a separate webpage closer to the launch date. Amateur radio transmissions will be announced in advance.

Frequency coordination with IARU was completed on 25.08.2025. More detailed information about the radio link will be published on docs.yksa.space.

Radio link parameters

Table 6. SAKHACUBE-CHOLBON radio link parameters
Parameter	Value
Frequency	437.350 МГц
Callsign	RS18S
Transmitter power	2 W (Max EIRP 33 dBm)
Modulation	GMSK
Data rate	2400 bps primary, 4800, 9600 or 19200 bps for payload data
Protocol	USP, AX.25, SSTV
SSTV modes	Robot36, Robot72
Emission designators	4K8F1D, 9K6F1D, 11K3F3F, 16K0F1D, 19K2F1D
Transmitted information	Telemetry, images, audio messages, SSTV postcards