Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (5,878)	$ (6,281)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation	417	1,573
Loss on disposal of assets	2	0
Depreciation	5	3
Changes in operating assets and liabilities:
Prepaid materials	115	414
Prepaid expenses and other current assets	549	(108)
Other assets	0	1
Accounts payable	424	(1,521)
Accrued expenses	640	(446)
Payroll liabilities	(995)	(703)
Other current liabilities	23	46
Net cash used in operating activities	(4,698)	(7,022)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(6)	0
Net cash used in investing activities	(6)	0
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercise of warrants	204	0
Net cash used in financing activities	204	0
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(4,500)	(7,022)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING BALANCE	88,570	111,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, ENDING BALANCE	84,070	103,978
RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH
Cash and cash equivalents	83,960	103,868
Restricted cash	110	110
Total cash, cash equivalents and restricted cash	$ 84,070	$ 103,978